Gold Velotech Manual

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Velotech Manual Draft Version 1.13
©Graeme Freestone King 2009-10
Velotech Cycling Ltd delivers training and assessment to National Standards in all aspects of bicycle mechanics
and workshop practices. This manual has been written to assist in that process.
Please note that working on bicycles requires a level of skill and knowledge, and is inherently liable to place the
operator at risk of injury. Please ensure that you take adequate precautions to avoid injury including the use of
appropriate personal protective equipment (PPE).
Graeme Freestone King nor Velotech Cycling Ltd will not be held responsible if the procedures outlined below
result in damage to components, failure of components, injury or death of operators or third parties as a result of
these procedures being followed.
These procedures have been drawn up following best industry practice and utilising a variety of manufacturer’s
instructions, but if in doubt, operators should consult manufacturers literature or seek more qualified assistance.
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Contents
Table of Contents
Workshop Practices ................................................................................................................ 4
Brakes ..................................................................................................................................... 15
Bottom Brackets..................................................................................................................... 21
Gears....................................................................................................................................... 26
Headsets.................................................................................................................................. 37
Hubs......................................................................................................................................... 42
Tyres & Tubes......................................................................................................................... 49
Frames..................................................................................................................................... 54
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Module 1 - Workshop Practices
What do we mean by workshop practices?
Workshop practices cover a wide variety of topics, from looking after tools, to the disposal of waste
materials. You and your work area should always operate as safely and efficiently as possible. It is not
possible to do this if the workshop is untidy and poorly organised, with tools, parts and waste scattered
and intermixed as is the case in many workshops. There are many things that can be done, often
including small changes that can be made, which will increase the safety of all workshop users as well
as improving the efficiency and effectiveness of the workshop as a whole.
Work Stands
A stable, strong work stands is a must; there is no way in which you can work properly and safely on a
bike without one.
The work stand you use should be in good working order.
Keep the clamping jaws in good condition, as this will
reduce the possibility of damaging the bike's paint or frame
tubing. If possible the cycle should be clamped by the seat
post as this will minimize the possibility of damaging the
cycle.
If the seat post is made of a potentially delicate or easily
marked material, then a substitute seat pin or specialised
“dummy” should be used instead.
If the bicycle has been set up for the rider and the seat
post needs to be removed, remember to mark any height
setting with removable adhesive tape before disturbing the
position of the seat post.
If it is not possible for any reason to use either the bicycle’s
normal seat post or a replacement, there are two other
possible clamping areas; the seat tube or the top tube.
The seat tube, at a height where the seat pin is supporting
the inside of the seat tube would be the preferred option in
these cases, with the top tube being the least favoured
alternative. Beware of clamping on top of any cable guides,
or clamping cables against the frame.
Fig 1.1 – A typical “pillar type” work
stand. A stable base and good clamp
are essential.
Some stands are designed to support the bicycle under the
bottom bracket, with a stabilising attachment to the stand provided by the forks (if fitted) or the rear
ends. These types of stands are often a good option for bicycles with complex tubing shapes, “aero”
seat tubes / seat posts or very short seat tubes / seat posts.
Where the seat post or frame member is being used as a clamping point, great care should be taken
not to over tighten the clamp. Many bicycle frame tubes are thin walled and relatively delicate and can
easily be damaged. Seat posts are less vulnerable to this than frame members, but mechanics should
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still exercise care. Dummy seat posts are usually made to withstand such pressures.
Having the cycle in a work stand will reduce the likelihood of the cycle or its components from being
damaged when work is being carried out, and it is also safer and more comfortable for the mechanic.
The risk of personal injury will be reduced if you are working in a safe and comfortable position.
The basic safety rule in the workshop
Know what to do if there is an accident or a problem
Use personal protective equipment (P.P.E.)
Keep work areas clean and tidy
Avoid working alone.
Observe what is happening elsewhere in the workshop for possible dangers.
Use the right tools for the job
Check the condition of the tools before use and ensure that they are clean and in good
condition. Clean tools immediately after use.
Wherever possible, work away from your body, and always think about the potential for any part
of your body to come up against a sharp edge, a hard surface, or to be caught between the tool
and the bike.
Long hair should be tied back, personal jewellery removed (especially chains and bracelets) and
ties or scarves removed.
Avoid over reaching and lifting large weights see the HSE notes on Manual handling available
from HMSO.
Accidents and problems
Fortunately, most cycle workshops and other environments in which mechanics work are reasonably
safe, provided that the people working in them take the various rules and suggestions below to heart,
and follow them.
Occasionally things do go wrong, and in some circumstances, not being aware of the right thing to do
can not only cause you a problem, but possibly also lead to others being affected. To a certain extent,
what to do should be covered in your induction, which, however informal should be carried out on your
first day at a new place of work.
It is in this context that we should also mention FIRST AID.
All workshops should have a first aid kit and just as important, someone who is aware of the basics of
first aid. It is worth making yourself aware of the contents of the first aid kit, so that in an emergency
you will at the very least know if you are likely to have the materials needed to render assistance.
Organisations like St Johns Ambulance run first aid courses ideal for people involved in the workplace,
with machine tools, or sports groups. Such courses, whilst they do cost time and money to attend, are a
good idea if you find yourself in charge as a workshop or related space.
There should also be an accident book to record reportable incidents. Normally this reporting is done by
the senior member of staff present, or the nominated first aider.
Generally you will find the name of the nominated frost aider on the Health ^ Safety poster that is
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displayed in the workshop. These posters are supplied by the Health & Safety Executive via HMSO and
outline your responsibilities and what you may expect from your employer, as well as giving other key
information with regard to Health & Safety law as it is administered by the HSE.
A couple of things to keep in mind if things do go wrong are:
Act in a way that protects yourself, as well as the victim of the accident. There is no point in
trying to help someone if you, too, are then injured and require assistance! As an example, if
you suspect someone has been electrocuted, switch off the power to the tool or appliance they
have been using at the isolator switch before touching them, or you too might suffer the same
fate!
Above all, reassure anyone who is hurt. They don’t want to know that the ragged cut from the
screwdriver that has just skated across their palm looks nasty and is filthy, they want to know
that you have the situation under control, that you are calm and collected, and know what to do.
Personal Protective Equipment (PPE)
Personal Protective Equipment (PPE) is important. Not only can it help to prevent traumatic injury, but
in the long term, the use of PPE can have important implications for general health.
The items discussed below are a minimum for most workshops – more specialist workshops, where
other, more complex or technical operations, such as welding, brazing or shot blasting are carried out,
should have the corresponding items of PPE and these should be used when appropriate.
There should be an appropriate Health & Safety policy in place (under current legislation, the Health &
Safety at Work Act, 1992, this needs only to be written if there are 5 or more employees in the
business, but a policy should exist regardless of numbers and be included in any induction of new staff
members). Part of this Health & Safety policy should be the provision of PPE.
For a general cycle workshop, PPP should include (but not necessarily be limited to):
Latex or Nitrile gloves (Nitrile is generally a better option because of problems related to latex
allergies)
Barrier cream (as an alternative to gloves)
Hand cleaner
Clear eye protection
Dust Mask
Apron
Whilst it is not strictly speaking an item of PPP, there should also be a comprehensive First Aid kit. You
should know where it is and who the designated first aider is, if there is one.
This information is generally included on the Health & safety poster which is required by law to be
displayed somewhere in the workshop area.
Clean and tidy work areas
The most common cause of injury in the workshop environment is tripping and slipping. Care should be
taken to ensure that the floor area is kept clear of slip hazards (i.e. loose paper, ball bearings, packing
material, oils and greases) and trip hazards (i.e. power tools, remnants of cabling, nylon packing bands,
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parts of bicycles).
Waste materials should be correctly
disposed of. New parts and / or parts
awaiting collection by the customer / held
in storage should be shelved in
appropriate containers in an organised
way.
Avoid piling parts on top of each other, or
having boxes of parts piled high.
Keep the bench top clear of all but the
work in progress, the tools that are in use
Fig 1.2 – Well organised work stations
moment to moment and containers for parts or materials
that are used on a day to day basis. Do not allow it to
become a dumping ground for “things that might come in useful one day”. This will help you work
efficiently and cleanly, as well as reduce the potential for accidental damage to yourself, tools or the
parts you are working on.
If possible, it is good practice to have a “dirt” and a “clean” bench so that jobs that need to be kept
clean (servicing of small items like the internals of hub gears) can be worked on away from jobs that
might produce dust or swarf, shed a lot of oil or dirt, or might otherwise make it difficult to service small,
fragile or easily marked parts without danger of contamination or damage.
Working Alone
In general, wherever you can, avoid working alone.
Injury is always a danger, and especially where cutting, pressing or power tools are involved, the
injuries can be far from trivial. The same applies in the case of lifting heavy or awkwardly shaped items,
or working at heights (i.e. on a step ladder to reach an item on a high shelf, or to gain access to a loft
space).
If you do need to work alone, be more vigilant to avoid injury, take extra care to use PPE and, make
sure that there is a telephone where you can reach it with the minimum possible need to move.
Look at the jobs you are considering tackling yourself and ask “what is the potential for injury, is it a
high risk operation, can I leave it until I have a colleague in the workshop with me?”
Observe what is happening around you. Remember that safety in the workshop is the concern of ALL,
both legally, and it might be argued, morally! This means that you should be aware of what you are
doing with relation to any colleagues or others who may be with you in the workshop space, as well as
anything a colleague may be doing that could affect you.
As an extreme example, don’t set up to TIG weld a boss onto a frame in the middle of the floor area of
a general workshop...the hazards this might produce include the brightness of the arc produced by the
welding apparatus (a hazard to anyone looking into the workshop), sparks, possibly a trailing cable tot
the TIG machine, hot metal, plus the inconvenience to others working around you.
Of course most situations are not this extreme – but even a colleague using volatile adhesives in a
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closed workshop, for instance, may provide a hazard to themselves, you and others.
Waste materials
You have a legal obligation to dispose of waste materials in the correct manner. Remember, ignorance
of the law is no defence! The legislation applicable to waste materials is the 'Environmental Protection
Act 1990, section 34, entitled ‘Duty of Care', which came into force on the 1st April 1992.
Waste materials should be identified, stored and ultimately disposed of in the correct manner. If you
have any queries concerning disposal, these should be discussed with your local Council, as they are
the primary 'Authorised' waste collection agency.
Waste materials include such things as, used cycle parts and accessories, packing materials, waste
lubricants, rags and cleaning fluids etc.
Separate waste, and store in suitable containers to await collection, ensuring this does not block any
fire exits/frequently used gangways etc.
Tools
Without question your workshop should have a full range of good quality tools. Having the right tool for
the job not only saves time but also helps to prevent the bike, component, paint being damaged and
also helps to prevent the likelihood of injury to your colleagues or yourself.
It is, admittedly, very difficult to make sure you have all the tools that will do every job. However, every
effort should be made to purchase new tools on a regular basis, to replace damaged and worn ones,
and bring in new tools for new products at the earliest opportunity.
Before commencing any job, ensure you have all the tools that you will need to complete it.
Tools should be stored in a safe and logical manner, and be readily available for selection, use and
return.
The most efficient method of storing tools is on a Shadow Board,
or in drawer-style storage with a location for each tool. This
system encourages the practice of returning tools after use and
improves productivity by not having to search for tools every time
you want to use them. It will also highlight missing tools at the end
of each working day.
As a rule of thumb, tools should either be in the mechanics hand
being used or they should be hanging in their place on the
shadow board (or in other safe, clean organised storage).
The correct tool for the job, correctly applied, should always be used as this will reduce the risk of
personal injury, damage to the component, the cycle or to the tool itself.
When you have finished with any tool it should always be cleaned and checked for any signs of
damage. The last thing you would want to do is pick up a tool that is covered in grease or has been
damaged rendering it unusable. This could prevent you carrying out the necessary repair.
Before using any tool, again check the tool for any damage before applying it to the part of the bike in
order to safeguard yourself, others and the bicycle from potential harm from either the tool itself or from
the consequences of its use.
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When using a tool, consider the safest and most efficient way to use the tool. As an example, when
using a spanner near the chain wheel area (say a pedal spanner being used to remove a pedal), try
and orientate the spanner and cranks so that you are working away from the chain wheels. If that isn’t
possible, it’s often best to put the chain on the outer chain ring so that if you do bring your hand into
contact with it, the teeth on the chain ring are not exposed. Remember, too, that you can apply far more
leverage at the end of a spanner than you can part way down, and so you can control the movement of
the tool better, as the less percentage of your total strength you are expending, the more accurate you
can be in its application!
Some further, essential pointers, additional to those at the head of this section:
Do not try to make use of a tool that you don’t know how to use correctly
Never use an edged tool towards your body
Always use two hands on an edged took, one to apply force, the other to control where the edge
or the point is acting
Never use a tool towards your face
Make sure that you use the correct PPE when using tools
Be aware of others in the workshop who may be affected by your use/misuse of tools
If you damage a tool, take it out of service immediately and inform the person responsible for
tooling that the tool is damaged and may need repair or replacement.
In the additional resources section t the end of the manual, you will find some suggested tooling lists.
You will also find a suggested tooling list near the beginning of each module, to help identify what tools
might be needed to accomplish the range of tasks outlined in that module.
Check lists and job cards
It is good working practice to use the check list or job card (as appropriate) in your course manual
before starting work on a cycle. (See additional resources section).
Using the check list / job card you can:
Assess the over all condition of the cycle
Check whether the work needed is possible with the tools available
Check whether you have the skill level required for the tasks identified
Assess whether the cycle needs to be referred to another more experienced or otherwise skilled
colleague
A comprehensive job card should be completed for every job, and, most importantly, during the
progress of the job, booked into the workshop. Such job cards should be retained in a way that allows
you to access the card for any given job easily and quickly.
A comprehensive job card gives you:
An on going record of the work requested or identified to be carried out on a cycle
A record of the parts used, as they are used...so reducing the danger of under billing a repair
because something has been forgotten
A note of the progress of the repair to date – so that if it becomes necessary to hand the job to
another mechanic, or to leave the job and resume it later, what has been done, and what parts
have been used up to the time work was stopped, is recorded
In the event of a recurring problem, an indication of solutions tried before is on record
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A measure of protection, if any dispute arises over the work requested, done, charged for or
recommended
It is a good idea to get the customer to sign the job card for any repair on collection so that you can
verify that the customer is satisfied that the instructions have been correctly carried out and that you
have made them aware of any further work that may be required, or safety issues that may have arisen
from your examination of the bicycle.
Workshop manuals
Collect as many of these as possible. The more reference material that you have to hand the easier it
will be to find any information or specifications that you may need.
At a time when the technology involved in bicycles is expanding and becoming increasingly complex,
very few, if any, mechanics can keep all the necessary information in their heads, so to enable you to
work efficiently and safely, an “in-depth” reference section will prove invaluable.
The internet also provides a rich source of information. Your first points of reference should always be
the manufacturers own website, followed by respected and peer reviewed alternatives.
It is worth commenting that some information on the internet is decidedly suspect and not necessarily
written by mechanics or other individuals with good knowledge or who follow good practices, so try and
find corroborative information to support methods and technique recommended by web sites, pages or
forums that are not directly connected to or moderated by manufacturers or recognised training
providers.
Manuals to look for as excellent general sources of information are:
Sutherlands handbook for bicycle mechanics (now going out of production, but excellent,
nonetheless)
Barnett’s manual for bicycle mechanics
Zinn and the art of mountain bike maintenance
Zinn and the art of road bike maintenance
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Lubricants and preparation materials
Purpose
Lubricants and other preparation materials are used in the assembly, maintenance and repair of
bicycles to assist in the smooth running of mechanical assemblies, to prevent damage to component
and as a method of preserving parts from corrosion or other forms of chemical or mechanical damage.
Technical Specification
There are many different types of lubricants and greases on the market. With frames and components
being manufactured in so many different materials, some of them with very particular requirements, it is
important to apply the correct preparation and lubricant materials.
It is not the brand name of these products that is important but the composition of the product. Each will
have its own specially designed chemistry, necessary for specific applications.
The following notes are a very basic guide to this very complex subject. It is always recommended that
if you have any doubt at all about the correct regime for preparation or lubrication, you should refer to
the manufacturer of both components, in the first instance, or to the manufacturer of the lubricant, for
further, complete and accurate information..
Why is it important to use lubricants and greases?
The consequences if you don't do this could be costly, not only in time or money but more importantly,
the prospect of injury to the rider should be considered.
Inadequate or incorrect use of, for instance, thread locking preparations, might result in components
vibrating loose which might have a safety implication for the rider. Incorrect lubrication of assemblies
might lead to the need to replace a component due to corrosion or premature wear. In extreme
circumstances, damage to the frame might result.
As a general rule, we can say that wherever there is an interface of two materials, whether similar,
subtly or totally different, there should be a barrier between them. There are a couple of exceptions to
this general rule, which are discussed in the modules concerned.
Where two materials are in contact with each other, a surface preparation or lubricant applied to the
facing surfaces will act as a barrier. The purpose of this barrier may be to reduce the possibility of a
chemical reaction between the two materials involved, or it may be to friction and wear and will prolong
the working life of a component.
Correct preparation or lubrication will also aid assembly and disassembly of components. This will save
time when servicing a component, as you will not, for instance, be faced with the prospect of forcing
components apart which have corroded together.
Preparation materials
There are a number of preparation materials that have been developed and marketed over the years
for specific tasks.
Some of these materials are designed to help components be fitted to one another in such a way as
one will grip another more effectively (thread-locking preparations, for instance) and some are designed
to prevent materials from binding together (carbon-prep, designed to allow carbon parts to be mated to
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other materials without danger of seizing or the degradation of the matrix in which the carbon mat or
strands are encased is an example).
In general, component manufacturers will make specific recommendations for the use of such materials
in their technical literature.
In some cases, traces of preparation materials will remain in components when they have been
removed from the bicycle, and traces like these are often a good indication of a manufacturers
specification, but mechanics should be wary of simply following what they find has been done before –
the last mechanic to service a part might not necessarily have been following best practice.
Where can I find out what the correct preparation material to use is?
Manufacturers of the component you are fitting or servicing
Component manufacturers assembly sheet
Preparation manufacturers helpline/website
Internet sites that carry this information
For non-retail readers, your local cycle shop will often have this data available.
What is the difference between an oil and a grease?
The difference is very simple. Grease is oil that has a soap like additive included into its composition.
This is added to thicken the oil so that it will adhere better to bearings and bearing races. Other
materials are sometimes added to these basic components to impart specific qualities to a grease.
These might include “Teflon” (PTFE), lithium oxide or copper for example.
When should you apply grease and when should you apply an oil type lubricant?
Greases are generally used in areas of high mechanical load where frequent fresh applications of
lubricant are difficult or impractical. The most common applications are in areas like bearing surfaces,
cables, on mounting points for cantilever or “V” type brakes, or as a simple chemical barrier between
metals, as in applications to bolts, metal seat posts or quill style handlebar stems, for example.
Oil type lubricants are generally used in areas where lubricant can easily and quickly be re-applied,
generally following a cleaning operation, or in areas where a viscous lubricant like a grease would not
give sufficient penetration, or areas where a viscous lubricant would cause dirt and debris to stick, or
otherwise impair the function of a part as a result of their viscosity. Examples include the chain, brake
and gear lever pivots or spoke nipples when wheel building.
Oil type lubricants can come as a liquid in a dropper or dropper type container, or be a spray
application. The oil may have other additives, such as “Teflon” (PTFE), or other carefully considered
properties, such as low sulphur oils used in thread cutting.
Bear in mind that more viscous lubricants (grease and thicker oils) will also particles of matter to a
greater extent than thinner, less viscous lubricants. Hence, although lighter, less viscous oils will be
washed off components more easily, say by rain, they might, with regular cleaning and application,
present a better alternative for lubrication than a heavier oil. Heavier oils might be more resistant to
removal, but will also tend to hold damaging foreign matter against the items being lubricated.
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Specific greases
Copper loaded grease (copper slip) may be applied when mounting components to others of dissimilar
Material, e.g. Aluminium to steel or alloy components. This will help prevent Galvanic Corrosion
Copper greases may also be used where titanium components are fitted together or to those of
different materials, but in the case of titanium, it is often better to use a very specific type of
preparation, called an anti-galling paste, such as that made by Rocol.
Lithium grease can be applied to cables, bearings and spindles, although a “Teflon” (PTFE) loaded
waterproof grease is often a better option. It is higher cost than lithium grease, but it might be argued
that it is less expensive to use in the long term as it tends to stay in place longer and to lubricate more
effectively.
Waterproof greases are specially designed for areas that will be subjected to severe weather
conditions.
“Teflon” (PTFE) – loaded synthetic grease is for fast moving parts such as hub bearings and bottom
brackets, it also has good waterproof properties. It is also a good chemical barrier against galvanic
corrosion and can be used like copper loaded grease.
These are only a few types of greases and lubricants on the market, but as you can see there are a
wide variety of different types, so it is important to ensure that you select the right material for the job.
Galvanic corrosion
Galvanic corrosion has been mentioned several times in this module – so what is it? When two 'like'
metals are placed side by side they will corrode at the same rate. When you put two dissimilar metals
side by side e.g. Aluminium and Steel, the rate of corrosion will be greatly increase, especially in the
presence of water. This is galvanic corrosion, so called because it is the result of electric current (albeit
at a very low level) being passed across the liquid between the two materials, exactly as happens in a
wet cell battery.
To guard against this you must use the appropriate grease or other barrier between them. You must
also take into account the increased rate of corrosion and be prepared to perform maintenance at more
regular intervals than normal.
How often should I use a lubricant / grease?
There is no set time scale. Simply remember that whenever you assemble, service or maintain any
component you should clean off any old preparation material, lubricant, dirt and debris with a suitable
cleaning agent. Remove the cleaning agent either by washing off with clean water and allowing to air
dry, or by drying it off with compressed air (or as directed by the cleaning agent manufacturer) and then
apply an appropriate preparation material, oil or grease.
An indication can be gained when bearings need lubrication by “grittiness”, or the fact that a bearing
rotates very freely indeed with no viscous matter.
A dry chain or jockey wheel will tend to “squeal” – regular cleaning and lubrication of the chain is
essential for longevity of not just the chain but also the other transmission components. It is difficult to
emphasise the “cleaning” part of this equation enough – especially on chains that are used in very
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testing environments such as off-road, or, slightly counter intuitively, in urban situations where there is a
lot of abrasives on the road that can easily transfer onto the chain.
Some new cheaper chains come with a thick, sticky grease on them. Unless indicated otherwise by the
manufacturer, this grease should be removed and an appropriate lubricant applied. Most higher quality
chains from “name” makers can and should be fitted with the packing lubricant intact, but as always,
check the manufacturers literature if you are in doubt.
Where can I find out what is the correct lubricant/grease to use?
Component manufacturers assembly sheet
Manufacturers website
Direct reference to the manufacturer of the component that you are fitting
Lubricant manufacturers helpline
Websites that carry this information
For non retail readers, your local cycle shop will often have this data available.
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Module 2 - Brakes
Brakes
Purpose
A brake system enables the cyclist to control the speed or stop the cycle, in all conditions.
Technical specification
This section only covers cable-operated rim brakes.
Tools
A number of tools are needed to fit, service and maintain the brake system. The most common and
essential ones are:
Allen keys 2,3,4,5,6mm.
Combination spanners 8,9,10mm.
13mm and 14mm cone spanners
Cable cutters
Cable end cap crimping tool
Fourth hand tools
Torque wrench with Alien key bits and sockets sized as above
Preparation
When fitting any brake system it is recommended that the manufacturer's instructions are followed. This
will ensure that the system will work as intended. Brakes are designed to control speed and stop the
bicycle in an emergency. If they fail to do the job for which they were designed, injury or death could
result.
Wheels must be true and correctly dished (i.e. with the rim centred over the locknuts) before you can set
up the brakes correctly. Hubs must be correctly adjusted, and tyres and tubes fitted and correctly
inflated.
The frame needs to be checked to ensure that it is correctly configured to fit the type of brake required
by the customer / supplied.
Both frame and forks need to be checked to ensure that they are correctly aligned and that the wheels,
when fitted into the frame, sit in the correct position relative to the frame (i.e. in most cases, centred on
the centreline of the frame, and centred relative to the brake mounts in the case of rim braking systems).
Where bosses are fitted for “V” type or cantilever brakes, these must be at the right height relative to the
wheel locations for the size of the wheel intended.
Likewise, where side pull or dual pivot callipers are to be fitted, correct drillings need to be in place in the
frame and fork, with appropriate counter boring for Allen key headed fittings, if present. The “drop” from
the centre of the brake centre bolt location to the centreline of the braking surface of the rim needs to be
correct for the depth of brake specified too.
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When assessing the bike for work on the braking system, always check that these conditions can be
satisfied and if any work is required in these areas, make sire it is noted and accounted for.
Fitting levers
When fitting any brake system it is recommended that the manufacturer's assembly guidelines are
followed. Doing so will ensure that the system will operate to the standard intended.
Fit components that are compatible with each other. This is particularly important in partial conversions
of conventional cantilever systems to those with “V” brake callipers.
Attention to detail during set-up should result in optimum performance.
The levers should be positioned to conform (currently) to British Standard 6102 pt 2, unless the
customer makes a specific request otherwise and their request is noted on the job card and signed off
by the customer on collection of the bike. The British Standard is that the right hand lever must operate
the front brake. The left hand lever must operate the rear brake.
Brakes are there to control speed and stop the bike, so they have to work effectively.
The levers should be positioned to conform to British Standards 6102. The right hand lever must
operate the front brake. The left hand lever operates the rear brake.
The levers should be positioned so the rider can easily operate the levers when riding the bike, (see
Figures in gears section for recommended positions). Fixing bolts should be tightened to the
manufacturer’s torque settings.
Fitting brake arms / calipers
Each type of brake has own fitting and set-up procedures, hence the need to refer to the specific
manufacturer's instructions to ensure correct fitting, adjustment and servicing requirements are met.
When fixing brake systems that locate on bosses, i.e. cantilever, and 'V' brake remember to ensure the
threads in the bosses are free from paint, corrosion or other contaminants, to enable the fixing bolts to
be inserted easily. New frames especially may have paint in the threads. The bosses themselves may
also have paint on them which, if left may limit the freedom of movement of the brake arm when fitted.
This paint must be removed. The boss should be cleaned with emery cloth. Emery cloth is also good
for cleaning corroded boss surfaces. Grease the bosses to prevent corrosion and to allow free
movement of the brake arms when fitted.
Brake calipers that are fixed through the fork crown, will also need a thin layer of grease on the fixing to
protect it from the elements.
Fixing nuts and bolts should be tightened to the recommended torque.
Ensure brake block carriers (shoes), where present, are installed the correct way round. It is essential
that the blocks are pushed towards the closed end when braking, not the open end. Ensure the correct
'toe in';' toe out' or parallel setting is applied, according to manufacturer's specifications. This will
reduce squealing to a minimum, and ensure optimum brake performance.
Fitting cables
There are several points to remember when cabling a breaking system:
Cables compatible with the system that is being installed must be used
16
Cable runs must be smooth, without tight arcs or kinks
Excessive cable lengths need to be avoided
If cables are too short the brakes may apply during cornering
If cables are too long they may snag, especially on mountain bikes used off road
Cables should be lubricated (using oil or grease) during assembly if they are not pre-Lubricated
at the factory.
Ferrules must be fitted onto the outer cable ends unless they are pre-fitted by the manufacturer,
or unless the other parts of the brake system do not require ferrules to be fitted, as is the case
with some brake levers and some barrel adjusters, for example.
Cable tidies must be fitted to prevent the inner cable from fraying
V-Brakes” are common on many MTB bikes. These calliper arms
attach to separate frame pivots on either side of the wheel. The brake
inner wire pulls the two arms together and forces the brake pads onto
the rim braking surface.” Linear Pull” callipers move the pad in an arc
moving downwards towards the rim. Shimano ® XT and XTR use a
parallelogram to move the brake pad straight to the rim rather than
through an arc.
Figure 2.1 A Typical V brake
The cantilever brake is also popular on MTB bikes, and is often
also found on both hybrid and touring bikes. Callipers are
attached to separate frame pivots on either side of the wheel.
The inner wire attaches to a straddle bridge, or it may continue
via a specially shaped guide to one side of the brake. In cases
where it attaches to a straddle bridge, a straddle wore connects
the right and left brake calliper arms. In the latter case, a short,
single straddle “arm£ attaches the specially shaped guide to the
other calliper arm. Cantilever pads move in a downward arc to
contact the rim.
Figure 2.2
brake
A Typical
Cantilever
17
Figure 2.3 Arc action of brakes
Road-type bikes may use a side pull brake. The brake callipers are
mounted to a single bolt centred above the wheel. Calliper arms extend
to the side and are pulled together by the housing and inner-wire. Side
pull calliper pads move on a downward arc toward the rim.
Figure 2.4 Typical side pull brake
.
Dual pivot callipers at first viewing look very similar to side pull brakes. The
two calliper arms however move in different directions. Seen face on, from
the mechanics point of view, the left pad swings downward toward the rim,
while the right arm swings upward.
Figure 2.5 Typical dual pivot brake
.
Figure 2.6 Inner cable nipple types - barrel
Figure 2.7 Inner cable nipple types - pear
Figure 2.8 Outer cable composition - brake
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Adjustment and set-up
The brake calipers or arms should be set up as specified in the manufacturer's instructions.
Brake blocks should be 'toe-ed in' or parallel to the brake surface, as specified
by the manufacturer. Figure 2.9 shows a toe-ed in brake block.
Brake blocks should be centered on the brake surface, as in Figure 2.10, and
should follow the curve of the rim.
Figure 2.11 shows correct vertical alignment and also poor vertical alignment.
Both brake blocks should meet the rim at the same height.
Figure 2.9 Brake
block positioning –
Toe-in
The distance from the brake block to the rim should be within the specifications
set by the manufacturer. Once set-up, the cable pinch bolt should be tightened
to the torque specified.
Figure 2.10 Brake
block positioning –
Centering
Figure 2.11 Brake block positioning – vertical alignment
Figure 2.12 Brake block
positioning – horizontal alignment
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Testing
Always test the brake system after installation or maintenance to check that it is set up correctly.
Once assembly and adjustment and set up are complete, squeeze the brake levers as hard as possible
a number of times, to ensure that all components are working correctly, and to seat the cables
thoroughly in their ferrules or other receptacles.
Check brake block clearance again and adjust if necessary, minor adjustments can be made with the
barrel adjuster, although in general it is desirable if the maximum amount of adjustment is left on the
barrel adjuster for the customer.
If more than a turn or two on the barrel adjuster is required, slacken the pinch bolt, pull any excess
cable through and retighten pinch bolt. Be wary of breaking strands in the cable at this point.
When the bike is removed from the work stand, it should be test ridden.
Removal
Removal is the reverse of the fitting process.
Maintenance
Inspect all parts of the brake system for signs of wear, corrosion or damage.
If the outer cable is cracked, corroded or kinked in any way it should be replaced.
If the inner cable is frayed, kinked or shows signs of corrosion it should be replaced.
Cables should move freely.
Check brake blocks for wear and damage, and for particles of rim material or grit lodged in
them.
Brake blocks should be replaced if the blocks are worn down to the wear line. Blocks should
always be replaced as pairs. If wear is uneven the fault causing uneven wear should be
identified and corrected.
Re-grease the brake fixing bolts.
Re-grease pivot points and cantilever bosses to prevent corrosion and aid free movement.
Check fixing torques.
Adjust brakes according to manufacturer's recommendations.
Compatibility
We recommend that when replacing any part of a brake system, an identical component to the one
removed should be used. If this is not possible because the component is obsolete or there are supply
problems, check to ensure that the new component will work correctly with the rest of the system.
Contact your supplier to give you this information. It is better to be sure than to risk the brakes failing.
Where to find more information
Manufacturer's help-lines
Manufacturers service or repair manuals
Manufacturer's have Internet sites where this information can be accessed
Barnett's Manual
Sutherland's Handbook for Cycle Mechanic's
Your local cycle shop.
20
Module 3 – Bottom Brackets
Purpose
The bottom bracket assembly is a bearing system that allows the axle and the chain set attached to it to
rotate freely without sideways play.
Technical Specifications
Historically, a widely used type of bottom bracket assembly has been the adjustable cup and ball type,
a typical example of which is shown in Figure 3.1. This type of bottom bracket is still commonly found in
cheaper bicycles, or bicycles for specific purposes (i.e. track bikes). There are two main variations in
this type of bottom bracket, the oldest and now least common, being termed “cottered”, the most recent
being referred to as “cotterless” or “square taper”.
Cottered cranks are fitted using a cotter pin which may either be continental sized (metric) or imperial
sized. These sizes are not interchangeable.
This type of bottom bracket has a separate axle, bearings, and cups, one fixed cup and an adjustable
cup, all of which can be replaced and serviced. The loose or caged ball bearings are sometimes
replaced by sealed bearings.
Figure 3.1 – Adjustable cup and ball bottom bracket
Figure 3.2 – Cartridge bearing bottom bracket
Most commonly specified and fitted today are the sealed cartridge types, shown in Figure 3.2. Such
bottom bracket units may have much in common in terms of crank fitting, as in many cases they are
designed to mount “cotter less” or “square taper” type cranks. Alternatively, they may be designed to
mount cranks which fit in a different fashion – using a spline patterned fitting.
Most recently, various types of ‘outboard’ bottom bracket systems have been developed. Broadly, these
fall into two groups, those with a single piece axle extending all the way through the bottom bracket and
attached to one of the two cranks, and those with a two-piece axle, part of which is attached to each
crank.
‘Outboard’ bearing systems all use sealed bearings which, once worn out, must be replaced. They are
not serviceable.
21
There is little cross-compatibility between manufacturers systems in outboard bearing types of bottom
bracket, and chain line is mostly fixed, though sometimes varied by the use of spacers under the
externally fitted bottom bracket cup and bearing assembly.
As always, service information on these systems can be found at the manufacturer’s respective
websites or on the printed instruction material provided with the product.
When any new system is encountered, the manufacturer’s specifications must be referred to for
assembly and dismantling procedures.
Within systems where an error is possible, it is important that the correct bottom bracket for the chain
set being fitted onto the bike is used. An incorrect bottom bracket may result in an incorrect chain line
that may cause a number of problems (as listed in the section on chain line and gear problems). An
incorrect type may prevent assembly, or may allow assembly but damage the components in the
process. If you are unsure, refer to the manufacturers instructions.
The important thing to remember is that the bottom bracket is the most heavily stressed component in
the whole drive-train and must be treated accordingly. Regular servicing and maintenance checks
should be performed to ensure that it is in good working order.
Bottom bracket lengths
The length of a bottom bracket is vitally important. Too long and it will move the chain set away from
the frame, too short and the chain ring will be too close to the bottom bracket shell. In both cases an
incorrect chain line will result, compromising shifting performance and long-term durability of the drivetrain components. The manufacturer’s specification sheet should be checked to determine which length
bottom bracket will be compatible with the gear set up if a direct replacement is not being carried out.
Bottom bracket threads
From the following table, you can see a variety of bottom bracket threads that are found on the market.
In the table please note that:
BSC (British Standard Cycle) and ISO (International Standards Organisation) sizes are fully
interchangeable. The 0.005m diameter (nominal thread description) difference is not significant.
Nominal thread description is the name of the thread type. The diameter value is not a
measurement
Shimano makes BSC cups “BC 1.37 x 24”
There is a difference in the particular shape threads (thread forms) between ISO and BSC
threads, as well as a variation in nominal thread descriptions.
22
Thread Types
BSC (1)
Typical
applications
ISO (1)
Italian
French
All Asian & American cycles, as well as
many others. All unmarked Taiwanese
& Japanese cups are BSC or ISO
threads
Most Italian &
some American
cycles
French cycles
from the mid
eighties or earlier
Pitch Cup O.D.
24 tpi
34.6 – 34.9 mm
24 tpi
34.6 – 35.9 mm
1mm
34.6 – 34.9mm
Drive side thread
direction
Non drive side
thread direction
Left hand thread
Right hand thread
Right hand thread
Right hand thread
Right hand thread
Right hand thread
Nominal thread
description (2)
1.370 x 24 tpi
(1)
Shimano (3)
36mm x 24 tpi
35mm x 1mm
(Right 3)
Shell ID
33.6 – 33.9 mm
34.6 – 34.9mm
33.6 – 33.9mm
1.375 x 24 tpi
(1)
Frame preparation
Before fitting a bottom bracket to any frame, inspect the threads in the bottom bracket shell for damage,
corrosion and clogging by dirt or paint. It is also worth checking that there are no protrusions into the
bottom bracket shell that might prevent a bottom bracket being fitted, especially where the replacement
unit is not the same as the original - a common problem is the bolt or rivet sometimes used to secure
the bottom bracket cable guides, where fitted, protruding into the bottom bracket shell, and preventing a
cartridge type bottom bracket unit being fitted in place of a unit composed of separate cups, bearing
assemblies and axle.
If the threads are damaged or corroded then the correct bottom bracket taps should be run through, to
clear the threads. This may not always be possible as the threads could be beyond repair. Before doing
this, ensure that there are no protrusions into the shell that would encourage misalignment of the taps
with the thread, or that might damage the taps in use.
In addition to checking the threads on the frame you should also inspect the threads on the bottom
bracket itself. Trying to insert a damaged bottom bracket into the shell could damage the threads in the
frame and prove to be a costly mistake.
Maintenance
Cartridge bottom brackets require no maintenance at all because the whole system is sealed.
When the bearings are worn or damaged, the assembly is replaced with a new unit
Adjustable cup type bottom brackets have bearings, axle and cups that can all be serviced,
adjusted or each part replaced as necessary.
Properly grease the internal and external threads of the bottom bracket and shell. Failure to do
this can cause the bottom bracket to seize in the shell and/or strip any of the mating threads,
either at time of assembly, or on removal.
Corrosion is to be avoided and to prevent this occurring, lubricants must be applied at regular
23
intervals. Bottom bracket units, like seat posts, are particularly prone to galvanic corrosion
measures need to be taken to prevent this becoming a problem.
You should never allow grease to touch the tapered shank of the bottom bracket axle unless
otherwise recommended to by the manufacturer.
BMX bottom brackets with a single crank (“Astabula” BBs), also sometime found on low cost mountain
style bikes use two bearing races press fitted into the frame, with two caged ball races trapped under a
gear side cone which threads clockwise onto the crank unit itself, also retaining the chain ring.
Adjustment is on the non gear side, via an adjustable cone and a locknut, both of which tighten
anticlockwise. These bearings are very prone to working loose and should be checked and maintained
frequently.
Chain line
Front chain line refers to the distance from the bicycle centreline to chain ring midpoint. Rear chain line
is the bicycle centreline to sprocket midpoint. Front and rear chain lines rarely match in practice. Chain
rings are frequently moved out to avoid having the chain rub on the outside chain ring when the gears
are in a small chain ring and small sprocket combination.
How to calculate chain line
The rear chain line is easily determined by measuring the distance from the drive side locknut to the
sprocket midpoint and subtracting that dimension from half the overall locknut dimension.
Front chain line is determined by measuring the distance from the seat tube to the chain ring midpoint
and adding half the diameter of the seat tube. This will give the front chain line dimension. Generally,
cycles with a single chain ring have a 40 to 42.2mm front chain line. Cycles with double chain rings
have a 43.5 to 45.5mm front chain line. Cycles with triple chain rings have 47 to 5Omm front chain line.
Factors affecting chain line
One, or a combination of the following things may cause incorrect chain line:
Fitting a new or different type of chain set. When fitting a new chain set, always check with the
manufacturer's specification to determine the correct bottom bracket length to achieve a correct
chain line. In the absence of this information, there is no way of telling if a new chain set will
give the correct chain line without fully fitting it.
New crank arm. If fitting a different type or new right-hand crank arm, you may find that it alters
the chain line. Always check the manufacturer's specification to ensure that there will be no
other complications.
Fitting a new bottom bracket. If the new bottom bracket is not identical to the old one, it could
move the chain set in or out relative to the bottom bracket shell, so affecting the chain line.
New rear wheel. When fitting a new rear wheel, check that the spacing on the axle is the same
as the old one. If they are not this may alter the chain line either in or out. It may also affect the
adjustment of the rear derailleur.
Increasing the number of gears. When increasing the number of cogs on a block or cassette, or
fitting a chain set with more chain rings, remember that the spacing will probably alter between
the cogs, and may alter between the chain rings, which in turn will alter the chain line.
Alignment of the rear-triangle. If the rear triangle is altered in any way, due to damage or to
accept a new wheel with a different OLN dimension, for example, this may also result in an
incorrect chain line.
24
Where to find more information
Manufacturers' help lines
Manufacturers have Internet sites where such information may be available.
Manufacturers service or repair manuals
Barnett's Manual
Sutherlands Handbook for Bicycle Mechanics
25
Module 4 - Gears
Purpose
The gear system allows the cyclist to maintain a pedal cadence that is comfortable and practical
irrespective of the terrain being covered,
Technical specification
Gear systems fall into two main categories, derailleur and internal (hub) gears. This section concerns
derailleur systems only.
Derailleur systems comprise of:
Levers
Cables
Derailleur’s, rear only, or front and rear Derailleur
Bottom bracket
Chain set
Chain
Freewheel (block) or cassette
Tools
A number of tools are required to install, service and maintain gear systems. This list is not exhaustive
but the most common and essential ones are detailed below:
Allen keys 3, 4, 5, 6, 7,8 and 10mm
Combination spanners 8-10mm
14mm and 15mm thin-walled socket spanners
Chain set extractor tool
Inner and outer cable cutters specifically designed for gear cables
Third/fourth hand tools
Torque wrenches, Iow and high range, with Allen key bits and sockets sized as above
Bottom bracket fitting / extractor tool or appropriate spanners for type
Workshop tools (generally shop/manufacturer) additional to above:
Gear hanger tap
Gear Lever boss tap
Gear hanger alignment gauge
Bottom bracket threading and facing tools
Bottom bracket fitting tools
Preparation
Before installing any of the components:
The frame should be in track (see separate section on frame alignment and preparation, for
more details)
The gear hanger should be tightly bolted to the frame, of the correct type, and correctly aligned
All necessary gear cable stops and adjusters should be on the frame, or locations for them
should be available
The frame and components should be inspected for cross compatibility
26
The bottom bracket shell should be faced if necessary (see separate section on frame
alignment and preparation for further details)
Threads should be checked to ensure that they are aligned correctly and clean. (see separate
section on frame alignment and preparation for further details)
Installation - bottom bracket and chain set
Always fit the bottom bracket in accordance with the manufacturer’s instructions.
Check manufacturer’s instructions concerning:
Bottom bracket length for chain line and compatibility with particular reference to the type of
chain set and gear system being installed (see details in the section concerning bottom bracket
types and chain line).
Bottom bracket type correct for intended use
If using a third party bottom bracket, that the tapers or spline pattern are compatible (see details
in the section concerning bottom bracket types)
Correct assembly sequence / lubrication / thread locking and tightening torques fro bottom
bracket cups into the frame.
Fixing bolt or Allen key nut torque to retain the chain set onto the bottom bracket axle.
Installation - shifters
When installing any gear system or component, you must follow the manufacturer's instructions so that
the assembled equipment works as the manufacturer intended. Always use compatible components.
Attention to detail during preparation and set-up will result in a smooth transmission and shifting.
When installing handlebar-fitting shifters you should position them so that they are as comfortable for
the rider as possible. There are standard positions for these levers, however, the customer and or the
manufacturer may request or instruct an alternative position.
Drop bars
The standard position is for the bottom of the lever to be in
line with the bottom of the bar, plus or minus 12.5mm
(approx half an inch).
It is important with drop bar levers that the cable route from
the back of the lever (brake and in some cases gear) does
not have a tight bend – cable entry to the lever from the bar
should be a smooth curve. Tight bends will impair function.
Try and avoid lumps under the tape just above the lever –
these can be uncomfortable and very irritating when riding as
well as being aesthetically poor.
Figure 4.1 Correct position for drop
bar gear / brake shifters
27
Straight bars
Straight bars can be found on utility, urban, children’s, mountain
and hybrid bikes which will use shifters.
The standard position is 24 – 45 degrees downwards from
horizontal. In general try to continue the line of the rider’s forearm
where it comes to the handlebar so that the wrist is not cocked or
rolled to reach and operate the brake / shift lever.
Having positioned the lever it is important to use a torque wrench
when tightening the lever-fixing bolt.
There are several reasons for this:
Figure 4.2 Correct position
for straight bar gear / brake
shifters
Using the recommended torque setting should prevent any
possibility of damaging the threads in the casting or on the
bolt.
It will also prevent fracturing of the casting itself.
Using a torque wrench ensures that the fitting is adequately tight, removing the risk of the lever
moving on the handlebars during operation. Both extremes could result in an accident and/or
injury
Installation - derailleur’s
When fitting derailleur’s, as with all other components, always follow the manufactures instructions.
When installing the front and rear derailleur’s, grease the fixing bolts before assembly to help prevent
corrosion and assist future disassembly.
Before fitting derailleurs, double check:
The derailleur’s that you intend to use are compatible with the shift levers
The derailleur’s you intend to use are correct for the gear range and chain wheel / sprocket
sizes that you have
The front derailleur has the correct fitting type (clip of the right size / bolt on fitting)
The front derailleur is designed to fit the seat angle of the frame (in general this will be the case
but there are odd exceptions)
Front derailleur
The front derailleur (gear) should be set at the correct height and in the correct orientation to the chain
set with:
The bottom edge of the outer derailleur cage plate about 2mm higher than the top of the teeth
on the outer chain ring when positioned to carry the chain over to the outer chain ring.
The part of the outer plate opposite the hinge should be parallel to the outer chain ring in most
cases.
Tighten the fixing bolts to the specified torque settings
Rear derailleur
The rear derailleur (gear) should be fitted to the rear hanger by the top pivot bolt, and tightened to the
correct fixing torque. Ensure the hanger is aligned and that the hanger fixing bolt, where there is one, is
28
correctly torqued.
Installation - chain
A compatible chain for the gear system fitted to the cycle must be used. Shimano, Campagnolo, SRAM
and many others make chains that are specific to their own or third-party gearing systems, and if the
right chain is not used, gear function will be
impaired.
If re-using an old chain, check it for
wear. Chains do not stretch but the
rollers between the links do wear –
use a chain wear indicator to check for
wear.
Match the new chain to the original, or
determine the correct length by other
means. There are many ways of
calculating the correct chain length. If
all the parts of the derailleur system
selected are compatible, then the
correct chain length should enable all
the gears to be selected and the rear
gear to maintain tension on the chain
at all times when the bike is being
ridden.
Having cut the chain to the correct length, fit the chain over the chain set through the front
derailleur, over the cassette or freewheel, and through the rear derailleur cage.
The chain must be joined in accordance with the manufacturer’s instructions, using a joining pin,
joining link or other device as specified.
The rider should be advised that they should never use the gears at the 'most extreme positions' as this
will cause accelerated wear and decrease efficiency. However, the mechanic should still ensure that:
The combination of smallest sprocket to smallest chain ring can be selected without excessive
slackness in the chain or the chain wrapped around the upper jockey wheel touching the chain
as it passes from the lower jockey wheel back towards the chain set.
The combination of largest sprocket to largest chain ring can be selected without excessive
strain on the chain. Normally this will mean that the chain must be deflected from a straight line
as it passes over each of the derailleur jockey wheels.
A good approximation can often be determined by putting the bike in top gear (largest chain ring
and smallest sprocket), and cropping the chain at a length that allows a vertical line to be drawn
through the centre lines of the rear axle and the two jockey wheels.
It is important to note that with some suspension systems it may not be possible to achieve this
as the swing arm movement may preclude it.
Installation – outer cable
Always use the recommended type and size of cable as per manufacturer’s instructions. This will
ensure smooth and accurate shifting of the gears.
When cutting and installing the outer cable:
The outer cable run must be as smooth as possible. Over-tight bends will increase friction and
result in poor gear selection and excessive wear and tear of cables and components. Bear in
mind that over short cables may also affect the freedom of movement of the handlebars.
29
Avoid over long outer cable, you don't want unsightly cable flapping around when riding the
bike, on some levers overlong cable will tend to kink, and on a mountain bike ridden off-road it
increases the chance of snagging.
Avoid cutting the rear section of outer (cable stop to rear gear) – it is already the correct length
When cutting the cable outer, try and cut as close to 90 degrees across the cable as possible –
outer cable cut “on the slant” will compress slightly and may also cause unwanted friction
Use ferrules of the correct size and type. These will prevent the outer cable fraying at the ends,
which could cause friction, resulting in poor gear selection. They will also help to hold the end of
the outer cable square in the cable guides, so reducing any tendency for the inner cable to drag
on the guide, increasing friction and compromising performance.
Once the outer cables are fully installed, run the inner cables through them (see Installation of
inner cable).
Ensure that the outer cables are all the way home into their locations in the levers
Where the outer cables will run under the handlebar tape, tape them firmly onto position on the
handlebar
Installation – inner cable
Always use the size of inner cable specified by the manufacturer to match the outer, and the gear
system in use. This is particularly important if you are using a third-party manufactured cable. This
ensures smooth travel through the outer cable, and accurate shifting.
The nipple on the cable end should be exactly the shape and size required to fit into the cable
routing in the lever.
Make sure there are no kinks in the inner cable once the cable is routed
Do not cut the inner cable until you have fully set up the gears – this is so that if you have to
rethread the inner cable for any reason, you can do so without it fraying in the outers (the uncut
end is soldered closed in a new cable). It also makes it easier to pull tension onto the cables
whilst you go through the set up procedure. Just coil the loose ends to prevent them snagging in
the transmission.
Once gear adjustment is complete and the inner cables can be cropped, fit cable end tidies to
prevent fraying.
Adjustment and set-up - Adjusting the rear derailleur
The rear derailleur has two functions. It moves the chain from one sprocket to another and maintains
chain tension.
Always refer to Manufacturers instructions for adjustment specifications.
Cable installation
1. Screw the rear cable adjuster all the way into the rear gear and then unscrew it 1 or 2 turn(s)
2. Ensure that the outer cable where it routes into the lever is pushed firmly into its location
(especially important in cases where the gear cable runs under the handlebar tape)
3. Ensure the inner cable runs through all the guides as specified by the manufacturer – on sports
bikes, check the under bracket guide is in place, correctly positioned and that the cable passes
over it correctly.
4. Ensure that the gear lever is in the “top” gear position
5. Set the upper limit screw (“high” adjuster) so that the top jockey wheel sits exactly vertically
below the smallest sprocket when viewed from the back, or as instructed by the manufacturers
specifications if this differs.
6. Route the cable as the manufacturer's instruction past the cable clamp bolt. Ensure that it
passes the correct side of the bolt. In most cases this is the left hand side of the bolt as viewed
from the back of the bike.
30
7. Do not wind the cable around the bolt unless this is indicated in the manufacturer’s instructions
– generally the cable path is straight past the bolt, trapped between the body of the rear gear
and under a flange on the washer under the bolt. As a general rule (especially in better quality
rear gears), do not trap the cable under the “tag” that sits at 90 degrees to the surface of the
washer- this tag is there to stop the washer turning as the bolt is tightened – in general, if the
tag is placed so that a correctly routed cable can pass under it, the washer is incorrectly aligned.
8. Pull the inner cable through so that it is tight, but does not move the rear derailleur position
relative to the sprockets.
9. Tighten the rear derailleur cable clamp nut / bolt to correct torque settings.
Adjusting the cable tension to correctly index the gears
1. Turning the pedals at approximately the normal pedalling speed, move the downshift on the
gear shifter so that it clicks once
2. If the chain does not climb up onto the next sprocket (say, the 8th sprocket in the case of a 9
speed system), then return the shifter to top gear, and increase the gear tension by turning the
adjuster a known amount (say half a turn)
3. Retry the shift. If the chain still does not move up to the next sprocket, repeat the above step
4. If the chain moves cleanly to the second to top sprocket, try each successive gear. If you reach
a point where the chain does not make the shift cleanly, return the system to top gear, increase
gear cable tension slightly with the adjuster, then retry until you get smooth changes all the way
down to bottom gear
Important Note:
When you come towards bottom gear, proceed with care. If the gear stops moving in response
to gear lever movement, the low gear limit screw may be preventing further movement. Unscrew
the low gear limiter progressively to allow the chain to travel up to, but not beyond, the lowest
sprocket.
If the gear system will allow the chain all the way to the bottom sprocket, adjust the low gear
limit now.
1. Once the chain has shifted cleanly onto the bottom sprocket, screw in the low gear limit screw
until it just starts to move the rear gear (you will need to look closely)
2. Unscrew the low gear limit screw ¼ turn
3. Try the shift from bottom to next to bottom gear then back again. The gear should allow the
chain to move to the bottom sprocket and remain there. If it doesn’t, back the low gear limiter
screw off another ¼ turn and retry
4. Once you are satisfied with the shift to the lowest gear, use your thumb and try to push the rear
gear into the rear wheel. The low gear limit screw, if correctly set, will prevent this.
5. Whilst in bottom gear, check the teeth of the top jockey do not make contact with the teeth of
the bottom sprocket – if they do, screw the “B” screw in, until they don’t. If you can’t screw the
“B” screw in far enough, the maximum sprocket size for the rear gear has been exceeded and
you will have to use a block or cassette with a similar bottom sprocket. If you checked your
compatibilities carefully at the start of operations, however, this should be OK.
6. Try the shifts from the bottom gear all the way to the top gear, allowing the chain to run on each
sprocket for a few pedal revs. Listen to the gears. Noise from the changer aside, you should
have smooth quiet running on each gear. A slight high-note chatter will indicate a gear cable
very slightly too tight, a slight low-note chatter, a gear cable slightly to loose.
7. Once you are satisfied with the shift in both directions, return the gears to the lowest gear hold
the gear shift lever across in the low gear position and gently pull the gear cable away from the
frame somewhere near its centre point. This will seat all if the cable outer into the ferrules and
the ferrules into their sockets, cable guides, lever and barrel adjusters. This will minimise gear
adjustment drift. Note that gear cables DO NOT STRETCH...gear adjustment drift is generally
31
due to slight compression in the outer, the pulling of the outer into the ferrules etc, or corrosion /
damage and friction build up in the cable system, or kinks caused by snagging etc.
8. You may need to fine tune the gear tension adjustment again after this step.
Figure 4.3 The parts of a rear derailleur. Note the high and low gear adjuster
screws (H and L screws) on different gears may be in different places, often on
the outer surface of the parallelogram. In this case, the H-screw is often the
lowermost or right hand, of the two. The B screw may also be on the derailleur
cage, not on the body. Check the manufacturer’s literature for definitative
information
Adjustment and set up - adjusting the front derailleur
The front derailleur has the purpose of moving the chain from one chain ring to another. It also serves a
secondary purpose in preventing the chain dropping off the chain rings.
Always refer to manufacturer's instructions for exact adjustment procedures.
Before starting the adjustment process, double check the compatibility of the front derailleur with the
system that you are using, the height that it is set at, and the orientation relative to the chain set (see
earlier notes).
Cable installation
1. Whilst on the small chain ring, move the chain to the largest sprocket on the rear. Adjust the
front derailleur inner or “low” limit screw until the chain just starts to rub on the inner plate. Back
the screw off to the point at which no further rubbing takes place, allowing about a 1mm gap.
2. If there is an adjuster on the frame for front gear cable tension, screw it all the way “in” then
32
“out” a full turn. If you have an “inline” adjuster, do the same. Note that if you have an inline
adjuster on a Campag gear system, it may be better to remove it as they can cause extra
friction that the system sometimes can’t cope with. If no other gear cable tension adjustment is
available, you may need to leave it in place.
3. Route the inner gear cable through its guides. If one of these is under the bottom bracket,
ensure the cable follows the correct path and passes through the appropriate eyes on the guide.
4. Follow the manufacturers instructions on the path through or around any cable routing on the
front gear, appropriate to the direction of pull – some front gears are designed for the cable to
pull from the top, some from underneath, and some can be used in either configuration. Check
which side of the pinch bolt to pass, and tighten the clamp bolt to manufacturers torque setting,
pulling the slack from the gear inner as you do so. Don’t overdo it!
Gear adjustment
The process is broadly similar to the rear gear but in the case of the front gear, there are several things
to note:
Some manufacturers have gear levers designed for either double or triple chain set; some
require a specific shifter for a triple. If you have followed the steps checking on compatibility,
you should have the right one.
On shifters designed for double chain sets, some manufacturers have, going up from the small
ring to the big, only one click, some have half a click part way between the full shift clicks to trim
the position of the front gear and prevent chain rub when the gears are at extreme crossover
points (big ring to biggest sprocket(s) at rear, small ring to smallest sprocket(s) at rear). Some
manufacturers also have this half click on the way back down from big ring to small. As a
general rule, these half clicks get lost if the initial cable tension is set too tight.
These half clicks are sometimes duplicated on shifters designed for triple chain sets.
Some manufacturers have multiple clicks between small and big rings. They make specific
recommendations about where the chain should be (small ring, big ring, etc) for a specific
number of clicks. Follow these recommendations.
The adjustment process:
1. Shift the rear derailleur to put the bike in top gear at the back
2. Turning the pedals at approximately normal pedalling speed, move the gear shifter all the way
across to shift the chain from small ring to the biggest
3. If the front gear does not move far enough to engage the big ring, check the outer (high)
adjuster screw the limiting factor by pulling the gear inner manually from about half way along its
length
4. If you can get the chain to the big ring by manually pulling the cable, but not using the lever, you
have probably not pulled enough slack out of the cable in the cable installation stages
5. If the gear overshoots and the chain drops off the big ring to the outside, replace the chain on
the big ring and screw the high (outer) adjuster screw until the inside surface of the outer plate
of the front gear just touches the chain, then back the screw off a ¼ turn and retry the shift. If
the front gear is now not moving quite far enough, back the high (outer) adjuster screw off
another ¼ turn and try again.
6. Check to see if the half shift (if present) acts going from big ring to small. If it isn’t there and
should be, drop the chain back to the small ring, reduce the front gear cable tension slightly and
try it again
7. Drop the chain back to the small ring and check that the half shift (if its supposed to be there) is
present
8. In the case of a triple system, shift the chain onto the middle ring and adjust the cable tension
so that if there is chain rub of the front gear at both ends of the sprockets at the rear, it is equal
in both the highest and lowest gears. This is normal, especially on bikes with short chain stays –
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it will be mentioned in the manufacturer’s notes.
9. If there is chain rub only on the low end of the cassette (biggest sprockets), increase the gear
cable tension slightly.
10. If the reverse is true, decrease the cable tension slightly
Figure 4.4 The parts of a front derailleur.
Note that on some gears the limit screws
may be reversed, with the high limit screw
being towards the centre line of the bike, the
low to the outside of the bike. They may
also be on the parallelogram arms. Check
manufacturer’s literature for definitive
information.
Adjustment and set up – final checks
Check all possible gear selections. In the extremes, largest chain ring and sprocket, smallest
chain ring and sprocket, it may not be possible to adjust the system so that the chain does not
touch the front derailleur cage. In some cases, selection of the extreme sprockets in the middle
chain ring may allow the chain to contact the front derailleur cage.
Try multiple shifts from chain ring to chain ring on all sprockets at the rear. If the chain drops off
to the inside of the chain set, adjust the low or inside limit screws by screwing it in a fraction and
retry the shift. In some cases, especially with third party chain sets, this problem can’t be
overcome and a “dogs tooth” can be fitted to the base of the seat tube to prevent the problem.
Trim the inner cables leaving about 25 – 35mm (1 – 11/2 inches), and cap the ends with cable
tidies
Testing
As when completing or fitting any fitting of new parts, maintenance or repair, test the cycle to
ensure its roadworthiness prior to competition, an important ride, or if you are a shop or
professional mechanic, signing off the job card
Test gear selection in all the gear combinations with the cycle in the work stand and then test
ride the cycle to ensure that all the gears run correctly under load
Full suspension bikes often require some fine tuning of the front gear when the bike is test
ridden due to the sag in the suspension system slightly altering the relationship of the chain to
the front gear position.
Removal of gear parts
Use the correct tools. This will prevent damage to the components, the frame and minimise the risk if
injury to yourself.
Check all components for visible damage as you remove them. This will show any further work that
may need to be performed, or component replacement that might be necessary.
34
Always remove the components in a logical order:
Put the bike in top gear at the rear on the small chain ring at the front
Disconnect cabling
Remove the chain
Remove the front gear
Remove the rear gear
Remove the cranks from the bottom bracket assembly
Remove the bottom bracket assembly from the frame
Remove only the components that you need to remove.
Dispose of any non useable parts in the correct manner.
Maintenance
The frequency and type of maintenance required will be determined by:
Weather
Road and terrain conditions
Loading of the cycle
Frequency of use.
All gear components should be cleaned and lubricated regularly, in particular the chain.
If outer cables are cracked or kinked in any way, they should be replaced.
If the inner cable is frayed, has any broken strands along its length or shows signs of corrosion, it
should be replaced.
Ensure the cables run freely at all points along their length.
The chain generally wears at a greater rate than the other transmission components. The chain should
be regularly checked for wear using a chain wear indicator. Early maintenance of the gear system, and
early chain replacement will maximise the service life of sprockets and chain rings. There are various
brands of chain wear indicator available
Compatibility
If you have a gear set that you wish to exchange any component, you need to establish whether the
component will operate correctly in combination with the rest of the gear set. This may apply even if you
are fitting a component from the same gear set made in a different year.
The best way to checks is to first refer to the manufacturer or supplier of the new component. They will
either recommend the installation or advise an alternative if your choice is not appropriate.
Shimano, for example, will be able to supply you with a compatibility list for its range of gear sets. This
should be so for all of the major manufacturers.
Reference to this type of listing will reduce the possibility of fitting incompatible components.
35
Where to find more information
Manufacturers assembly sheets
Manufacturers help lines
Manufacturers have internet sites where such information might be available
Burnetts manual
Sutherlands handbook for bicycle mechanics
36
Module 5 - Headsets
Purpose
The headset is a bearing assembly that enables the fork to rotate freely on its own axis within the
frame, to control the direction of the cycle, without binding or free play.
Technical specification
Steerer length (fork column) calculation
When fitting forks into a new or used frameset it is important to ensure that the steerer is the correct
length. If it is too short, the locknut may not have sufficient thread to be effective, or the stem may have
insufficient fork column to clamp on correctly. If it is too long then the locknut will not lock onto the
headset, or too many spacers will be required to allow the top cap to meet the top surface of the
handlebar stem, resulting in play.
To calculate the steerer length for threaded headsets you need to accurately measure the head tube
length and add the headset stack height. Between 1 and 2mm should then be subtracted to allow the
locknut to screw fully home.
37
The stack height of a headset may be defined as the overall height of all the headset components less
the height of the parts concealed in the frame when fitted.
To calculate the steerer length for an A-head system, an accurate measurement is needed of the head
tube length, the handlebar stem clamp depth plus any spacer washers. Added to this, the headset
stack height should be included, and 2-3mm subtracted.
If the steerer is cut too long, correct adjustment will not be possible without the addition of extra spacers
that in itself might have an impact on long-term adjustment.
Make sure the steerer is cut to the correct length, the cut should be square, even and all burrs (internal
external) removed.
Tools
To remove and service a headset, or to correctly install one, you will need some or all of the following
tools. This is not a definitive list. Some headset designs require special tools designed for that headset
assembly only. Following this list will, however, give you enough equipment to enable you to work on
most headsets on the market today.
Allen keys (various sizes, typically 4, 5 and 6mm)
Selection of headset-specific spanners
Vernier callipers
Internal (hidden set) sizing gauge
Headset press
Head cup remover
Thread less headset nut setter
Head race facing and sizing cutter
Fork crown race remover
Fork crown race cutter in various diameters
Fork crown race fitter in various diameters
Fork column die and suitable stock
Hacksaw or carbon saw (for cutting carbon fibre columns).
Hacksaw guide
Files: flat and 1/2" round
Preparations, greases and lubricants
Preparation – general
For any given nominal size of headset (1”, 1 1/8” and 11/4”) there are both ISO and Japanese Industrial
Standard (JIS) dimensions which do vary slightly away from one another. Both the internal diameter of
the head tube and the external diameter of the fork crown race seat vary accordingly to whether the
head tube and fork of the frame have been made or cut to suit ISO or JIS dimensions. Take
measurements before commencing fitting operations to ensure that you have appropriate headset
parts, and check that the preparation tools available also match the type of headset that you intend to
fit.
Bear in mind also that in the case of threaded headsets, thread profiles do vary between British and
Italian. French headsets have a different pitch as well as thread form, although they are seldom seen
nowadays. There is limited compatability etween Brirtish and Italian headsets, and no compatability
between British, Italian and French.
38
Here are some general tips which apply at all times when fitting a new headset:
Ensure there are no sharp edges (or damaged threads in the case of a headset for quill type
assemblies) that may damage the headset. If using a threaded headset, check the threads on
the steerer or fork column to make sure that they are free from corrosion, wear and damage and
are compatible with the headset you intend to fit.
Ensure the fork crown race is fitted square onto the fork crown so that, when assembled, perfect
alignment and concentricity with the lower head tube race is achieved. The fit should be tight, or
a light interference fit, with no play.
Check the sizes of the fork crown race seta and the criwn race itself as per the above notes on
head tube internal diameter and headset cup diameter. In the case of foeks with a carbon
column or other bonded forks, a crown race cutter should not be used, as it may interfere with
the integrity of the biond. In case of doubt, seek advice from the fork manufacturer or distributor.
Steerers should be cut to the correct length. The cut should be square and even and all burs
should be removed.
The correct length for the fork column, measured from the base of the crown race seat to the cut
end of the head tube, is the combined height of the head tube and headset stack height, less 23mm for threaded headsets, plus the required spacers and handlebar stem depth for A-head,
(see section on stack height). In the case of a carbon fork column, the column should be cut to
length with a specialised carbon saw or a fine toothed hacksaw and appropriate PPE should be
worn to prevent in ingestion of the dust created.
Fitting threaded headsets for quill-type stems
It is vital that the headset is fitted correctly, following the manufacturer's assembly and set-up
specification, to obtain optimum performance. There is no single set procedure for the fitting of a
headset but the following guide may be of help, in the absence of a specific manufacturer's instructions
sheet.
As in any workshop practice, always use the correct tools. Remember, bearing surfaces need to
be parallel and in line to work correctly.
Check the stack height and head tube length to calculate correct steerer length.
Measure the head tube, crown race bearing seat, head tube race and crown race dimensions as
appropriate to ensure compatibility.
Clean and prepare the head tube prior to fitting. If necessary, use the head tube reaming and
facing tool.
Clean and prepare the fork crown before fitting the crown race. Use the fork crown race cutter if
required, unless a bonded fork is involved.
Lubricate all interference fit parts with appropriate lubricant, to reduce the possibility of corrosion
and to reduce binding
To install the head cups always use a headset press. This will ensure that the cups are correctly
aligned and go into the frame square.
Fit crown race with crown race fitting tool, applying lubricant to the interference fit area, ensuring
that the crown race sits squarely on the fork column crown race seat.
If the steerer is alloy or steel it should be light smearing of grease before final assembly, to help
prevent corrosion.
Apply grease to all bearings and surfaces and assemble fork into the frame ensuring the
bearings are of the correct size and fitted correctly.
Failing to follow these processes may cause problems with set-up and future adjustment and
disassembly.
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Fitting thread less headsets (A-head) for thread less steerers
As with threaded headset (described previously) except stack height. The height of the handlebar
stems clamp, and any spacers should be added to obtain correct steerer length.
Headset adjustment and set-up
It is recommended that you follow specific manufacturer's instructions wherever they are available.
There are many variations in set-up and adjustment procedures and you should always ensure they are
followed for optimum performance.
If no manufacturer's instructions are available, the following provides a generic set of guidelines.
Installation should be as described previously.
Threaded headset
The adjustable cup should be tightened down hand tight.
The washer, keyed or keyless type should be fitted next. If the fork has a flat or keyway to
accommodate a key, it is generally preferable to use a keyed washer of suitable design.
The locknut should be fitted and tightened down by hand. Insert the handlebar stem, having
lubricated the quill and the outside of the expander cone/wedge and then tighten the locknut to
the specified torque setting whilst holding the adjustable cup with an appropriate headset
spanner.
Check the headset gives free rotational movement without binding and with no discernible play.
Bear in mind that tightening the locknut may push the screwed race more firmly into contact with
the threads of the fork column, although if held still with a spanner, it will not have rotated.
This may mean that the bearing tightens slightly, so easing off the locknut and screwed race by
a very small amount, prior to retightening and testing, may be required to achieve optimum
freedom of movement with no play
A-headset - also generally applied to concealed (hidden set) headsets
Fit the top bearing race/seal and adjuster/compression ring, spacers to the required height,
handlebar stem, cover or top cap and adjuster bolt.
Tighten adjuster bolt until resistance is felt and then check the headset for free rotational
movement without binding or free play. Continue until satisfied with adjustment.
Line up handlebar stem centring it on the front wheel and lock fixing nuts or bolts to
manufacturer’s specifications.
Check for free rotational movement and no play.
Final adjustments - both thread less and threaded headsets
When the cycle is completely assembled, remove it from the work stand and check for play by applying
the front brake and applying a forward and backward rocking motion to ensure the headset is correctly
adjusted. You should not feel any movement between the external parts of the headset and the parts
that rotate within them.
If you feel movement that it is indeed between the headset components and not attributable to, say,
poorly maintained suspension fork stanchions moving in the lower fork legs.
40
Removal
Use of the correct tools will prevent damage not only to the headset components but also to the head
tube and the fork.
Disassemble the cables (brake and or gear) and remove the front wheel before removing the
forks. This greatly simplifies the operation and prevents the possibility of damage to other parts.
Clean and check all components for damage as they are removed. This will highlight any further
work that may need to be performed.
Remove only the components that you need to. For example, if you are about to service the
headset and fit new bearing races, it may not be necessary to remove the frame cups and fork
crown race.
Should complete disassembly be required, the procedure is the reverse of fitting, using the
correct tools, that is to say, the crown race remover and head tube cup/race remover
respectively.
When the stem and handlebars are removed, remove them completely or secure them out of
the way so that they will not be damaged or interfere with work to the headset.
Do not allow the bearings to fall out and to the floor. Dispose of them in the correct manner.
Maintenance
Check all components for wear, including corrosion.
Kinds of wear commonly found in headsets are brinelling, corrosion, damaged bearings and
bearing surfaces, thread failure of both headset and fork components, and loose interference
fitting parts.
Use the correct greases and lubricants.
Inspect the inside of the head tube for wear and corrosion.
Use the correct sized ball bearings or bearing races as specified by the manufacturer.
If the bearings are in a race then they should be replaced with balls in a race if possible.
Grease the fork column (inside, for threaded/outside for A-head), before installing the stem. This
will aid removal and also help prevent corrosion.
Clean surplus grease from all components after completing the job.
Check fork and steerer for correct alignment, (refer to frame alignment section).
When installation is complete, check to see if the headset is correctly adjusted on the stand, on
the ground and by road testing.
Compatibility
When replacing a worn out headset, it is important to ensure that the stack height of the old one is
equal to or greater than the new headset, to ensure correct fitting is possible. It may be necessary to
add some spacing or to refer to the customer to discuss further trimming of the fork column if the new
headset has a lower stack height than the original. It is clearly best to replace on a like-for-like basis as
regards stack height if at all possible.
Where to find more information
Manufacturers' assembly sheets
Manufacturers' help lines
Manufacturers' have Internet sites where such information available
Barnett's manual
Sutherland's Handbook for Bicycle Mechanics
41
Module 6 - Hubs
Purpose
The hub is system of bearings; cups, cones, axle and shell that allow the wheels to rotate freely without
sideways play.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
42
Complete quick release skewer
Complete hub axle
Lock nut
Drive side washer
Drive side axle spacer
Seal ring
Spacer
Dust seal
Drive side cone
Axle only
Non drive side cone
Non drive side spacer
Non drive side washer
Non drive side rubber seal
Free hub body retaining nut
Ball bearings
Free hub body complete
Adjustable cone hubs
This type of hub has a threaded axle with ball bearings, either loose or in a bearing cage. The bearings
seat into a retainer fixed into the hub shell and have a cone that is threaded onto the axle. In most
cases the cones are adjustable from both sides on the front wheel and one side on the rear.
Remember that you only ever dismantle the rear hub from the non-gear side, as this will always ensure
that the axle is refitted central to the hub. The rear hub will also have a thread-on freewheel or free hub
fitted to one side of the hub shell. The rest of the hub is made up of dust caps, spacers and lock nuts.
Parts of the adjustable cone hub:
Hub shell - This is the main body of the hub. It is manufactured from a wide variety of materials,
from steel to titanium. The hub has the bearing housing inserted into the shell. The hub also
comprises two flanges, which have the holes drilled for the spokes. The number of holes can
normally be anything from 12 to 24 holes in each flange, 24 to 48 holes in total on each hub,
dependent on what the wheel's intended use will be.
Axle - This is a threaded rod that goes through the hub shell and on which, once the bearings
and cones have been assembled, the wheel rotates. This axle is either solid or has a hole
through the centre for a quick release skewer.
Cup or bearing housing - This component is usually inserted into the hub shell during
manufacture. It can be either a permanent part of the hub or replaceable. It has a radius surface
onto which the bearings run.
Cone - A cone is normally threaded into position on the axle. Like the cup, it has a radius
surface upon which the bearings run. The cone is an important part of the whole hub set-up. If
the cones are not adjusted correctly then the hub will not rotate properly. Too tight and the
bearings will not rotate freely. Too loose and there will be side to-side play. Both extremes may
lead to premature wear or failure of one or more of the component parts. It takes a great deal of
skill to correctly adjust the cones. Time should be taken to ensure that the cones are always
correctly adjusted. This can be quite a skilled operation.
Ball bearings - These are perfectly round, hardened steel balls. They come in a wide range of
sizes. The most important thing to remember is to ensure that the correct sized bearings are
fitted into the hub. If you are unsure of the size of bearings required, use reference material.
Dust cap - This helps to prevent foreign particles from entering the hub assembly. It can be
made from plastic, rubber or steel and can be part of the cone or separately threaded or
pressed onto the outer end of the hub.
Seal - This is a piece of rubber that is attached to the cone, dust cap or axle spacer and its
function is to fill the gap between the dust cap and the axle to prevent any foreign particles
entering the bearing surfaces. There are various different formats, according to the
manufacturer of the hub, its quality and the purpose for which it was designed.
Locknut - This is a nut that threads onto the axle and is tightened against the cone or washer.
This will fix the position of the cone to prevent the cone from becoming loose or tightening
during use.
Washers and spacers - These are usually made from steel, and are used to space the hub
assembly, to obtain the correct over-Iocknut dimension.
Cassette – Not strictly speaking part of the hub, this is a cluster of sprockets that slide onto a
free hub body and is held in place by either a lock ring, or by the top sprocket being screwed
into the free hub body.
Cassette or free hub body – In some types of hub (by far the most common in the UK at the
time of writing) this assembly provides the support for the far right hand (gear side) of the rear
axle, as well as providing the mechanism that allows the cassette to remain stationary as the
bicycle rolls forwards.
Freewheel - A set of gear cogs on a freewheeling mechanism that is screwed directly onto the
rear hub. Normally there is no support in these assemblies for the rear hub axle, which simply
43
passes through the freewheel.
Tools
A number of tools are required to install, service and maintain a hub, the most common, and essential
ones are detailed below:
Allen keys 2.5mm-10mm
Cone spanners 13mm-19mm
Combination spanners 13mm-19mm
Axle vice
Chain whip
Cassette lock ring removing tool
Selection of freewheel removing tools
Torque wrench with Allen key bits and sockets sized as above
Preparation
The frame and forks should be checked for damage and alignment. The dropouts should be checked to
ensure that they are parallel and in line with each other. For additional information see 'Frame
alignment and preparation' section.
If you are working with a cassette type hub where the freewheel mechanism normally remains attached
to the hub, you will find the stripping and reassembly of the hub much easier if you take the cassette off
the cassette body. In the case of a hub with a screw-on freewheel, in general you have no option other
than to remove the freewheel.
See the end of this module for notes on how to carry out these procedures.
Dismantling
General tips for dismantling a hub assembly:
When you are dismantling any part of the front or rear hub it is important that you check each
part for wear, damage and corrosion. If you do this it will highlight any work that may not have
been originally specified by the customer. If you then put this information onto the job card, it
can be brought to the customer's attention, which may result in additional work.
You should always dismantle the rear hub from the non-drive side. Although it doesn't matter
so much with the front hub, it is advisable to get into the habit of working from the non-drive side
on both hubs to save confusion. Front hubs for disc brakes should generally be dismantled from
the non rotor side.
When removing the cones, prevent the bearings from falling onto the floor or workbench.
Always use an axle vice to hold the drive side of the axle. Putting the axle directly into a vice will
cause damage to the threads.
Process
Remove the quick release skewer (if present) or the track nuts from the hub spindle. If the wheel has a
disc brake rotor, remove this also being careful to store the rotor in such a way as to prevent contact
with oil or grease.
There may be a rubber seal over one or both sides of the bearings, which should be carefully removed.
Clamp the wheel axle in the appropriate slot in the axle vice, in the case of a rear wheel, gear side
downward, in the case of a front wheel for disc, disc mount side down. For other front wheels, one
normally clamps them disc side down so that the work is always consistent.
44
Hold the cone still using an appropriate sized cone spanner and undo the locknut anticlockwise, either
using a cone spanner or an open ended ring spanner if there is no problem doing so. In general we
would not advise using a cone spanner on a lock nut if there is no need as a result of the design to do
so. A cone spanner is designed for situations where access to the spanner flats is very restricted and
you will note that the jaw of the spanner is, in these situations, supported on both sides and hence
cannot twist, so damaging the tool.
Remove and lay out in sequence, the lock nut, any washers and spacing units and the cone (which will
usually unscrew anti clockwise up the axle).
Hold the uppermost end of the wheel spindle and undo the vice. Lift the wheel by the spindle until you
can support it from underneath, then cup your hand over the uppermost end of the hub. Turn the wheel
over, and then withdraw the wheel spindle from the hub, so that if any balls fall out, they fall into your
hand.
Lay the spindle and the wheel onto the bench and using a magnetised screwdriver or probe, retrieve
the balls from the hub, noting if the left and right sides of the hub have the same sized ball bearings or
not, and how many there are on each side.
If there are plastic or rubber dust seals present, fixed to the hub itself, these can usually be removed by
gently sliding the flat of a large screwdriver blade under the innermost lip, and very gently and carefully
prizing them free. If it takes a lot of force to do this, leave them in place. If such seals are metal, they
are also best left in place.
If you do not need, on inspection, to replace the cone of the cone and locknut pair, which up until this
point have remained undisturbed, check that the locknut and cone are fully tight against each other. If
the cone does need to be replaced, not the amount of spindle showing out of the locknut, and on
reassembly with the new cone, duplicate this, in order to centre the axle in the hub.
Maintenance
When performing any maintenance procedure to a hub, check every part for wear, damage and
corrosion against the manufacturer's specifications.
Remove all traces of old grease, to avoid contamination of the new grease.
When servicing any hub, always use a good quality bearing grease.
Check all parts for wear and damage.
Replace worn parts with new identical parts.
Replace bearings even if they look satisfactory. Wear may not be visible to the naked eye.
Adjust the hubs so that the wheel runs freely and without play.
Compatibility
There are numerous compatibility problems you may experience with hubs, so it is always advisable to
replace like with like. Areas where compatibility can be an issue are:
Axle diameter and thread.
Whether there is a keyway in the axle or not.
Radius of the cone face that interfaces with the bearings.
Overall depth of cone and or spacers.
45
Size and quantity of bearings.
Over lock nut dimension of the hub would usually be 90mm or 100mm front, 110mm-135mm
rear (possible 140mm for some tandems, drum brake designs and other specialist applications)
Reassembly
General tips for reassembly of a hub:
Keep everything as clean as possible – dust, grit and swarf from the bench top are your enemy
and will not only prevent the bearing running smoothly, but will also accelerate wear and tear.
When assembling hubs ensure that the same size and quantity of bearings go in as came out
Do not assume that the bearings you took out of the hub were the right size, or right in numberit’s always worth checking against the manufacturer’s specification if you are unsure. Keep the
ones that you took out and cross check that you have removed the right number and type – it is
possible to leave a ball inside the hub body which will not stop you reassembling or adjusting
the hub, but which will make a noise when the wheel is serviced and back in the bike.
Remember that doing a quick release up compresses the hub axle slightly. A very slight amount
of side to side play is therefore admissible in quick release hubs, so long as the play is
eliminated by a correctly tightened quick release. If the wheel is going to be trued in a jig after
reassembly & adjustment of the hub, eliminate any side to side play as it will make it impossible
to accurately true the wheel.
In highly critical situations, adjust cones with the quick release done up and the wheel in the
bike.
As when dismantling, always use an axle vice to hold the drive side of the axle. Putting the axle
directly into a vice will cause damage to the threads.
Make sure that when the hub is fully assembled there is an equal amount of axle either side of
the lock nuts.
Use the correct grease.
Process
Make sure that you have all the parts laid out in easy reach and in sequence. Check that the cone and
locknut on the gear side on the rear hub, or the rotor side on a front hub for disc, are tight against each
other. Ditto the locknut and cone on the “normally undisturbed” side of a “normal” front hub.
Load both bearing cups inside with grease. Waterproof PTFE grease is very good in this application.
Introduce the right number and size of balls into the gear side bearing cup. Refit any dust seal that may
have been fitted to the hub body (rather than the spindle) the right way up. Carefully re-insert the
spindle, taking care not to dislodge any ball bearings from the pad of grease that is sticking them to the
hub cup. Once the spindle is through, hold the free end, and put the gear-side end into the axle vice.
The gear side balls now can’t fall out.
At this point, in order to get the non-gear side balls into the hub, it may be slightly tricky. If there was a
seal on this side of the hub and it came out easily you can probably just drop the NGS balls into the cup
and reassemble the seal on top of them. If the seal didn’t come out, there may and any not be room to
feed the NGS balls between the spindle and the seal. If there is, well and good, load the correct number
and size of balls into the cup. If there is no space, gently lift the hub up the spindle until there is just
room to load the balls past the seal. The spindle running through the hub will prevent any balls finding
their way into the hub barrel.
Once the NGS balls are back in place, screw the NGS cone down, conical face inwards, until it is finger
tight against the ball bearings.
Reassemble the washers and spacing units in the same sequence as you observed when dismantling
46
the hub (assuming that was correct by the literature) on top, followed by the locknut. This should only
be tightened finger tight at this stage.
Adjustment
Hold the cone still with a cone spanner, and tighten the locknut down hard. Take the wheel out of the
axle vice and test how hard it is to turn the axle. In a high quality hub, it will probably be tight, but turn
smoothly. In a cheap hub the spindle may not turn at all at this stage.
Replace the wheel in the axle vice, hold the cone still and loosen the locknut 1/8 of a turn. Hold the
locknut still, and loosen the cone 1/8 of a turn so that it tightens “back” against the locknut. Remove
from the axle vice and test for free rotation of the axle.
Keep repeating the step above until you “just” get top the point where you have free rotation. Then try
and rock the spindle from side to side in the hub at several points on its rotation. If you get a small
amount of movement, reverse the last step, and try again but with 1/16 of a turn. If you get no
movement and free rotation, then the hub is adjusted.
The reason that you need to make sure that the gear side cone and locknut of a rear axle is fully
tightened down should be clear on inspection now – the cone is no longer accessible, it is below the lip
of the free hub or cassette body. If this side were to work loose in use, you would have to completely
strip the hub to fix it.
Cassette sprocket removal
The sprockets are usually retained on the hub body by a lock ring, although on some very old designs,
the smallest sprocket was screwed onto the free hub body and retained the sprockets underneath.
In the former case, far more common now, the sprockets are held still with a chain wrench whilst a
spanner and an appropriate lock ring tool are used to undo the lock ring anti-clockwise. A chain wrench
must be used, usually applied on or near to the biggest sprocket, to hold the sprockets still – as
otherwise the freewheel mechanism simply turns with the lock ring as anticlockwise force is applied.
In the former case, two chain wrenches are used, one to hold the cassette still, usually positioned on
the biggest sprocket, whilst the second is used in opposition, to turn the top sprocket anticlockwise.
Once the lock ring is removed, or the top sprocket in the case of old-school designs, the sprockets
simply slide off the cassette body. Note that the splines that the sprockets fit to are not all identical –
this is so that the sprockets will always sit “right way around” and in the correct orientation to each
other.
Replacement needs only a cassette lock ring tool (or a single chain wrench in the case of older
designs). The sprockets having been replaced, the lock ring is fitted (with care not to cross thread) and
tightened down with a torque wrench to the recommended torque. There is often a loud clicking noise
as this is done – this is the knurling on the lock ring engaging with the pattern cut into the surface of the
top sprocket – it’s perfectally normal. The knurling is there to prevent the lock ring vibrating loose. The
same procedure is followed in the older designs, with the top sprocket taking the place of the lock ring.
Cassette body removal
In general, it is not necessary to remove the cassette body from the hub to service Shimano and
Shimano-cloned rear hubs.
Having said that, if the hub shell or the cassette body are particularly heavily soiled, or if the cassette
free wheel mechanism fails, then removal of the body is required.
47
Removal in a genuine Shimano cassette body is done after the wheel spindle has been removed, by
use of a 10mm Allen key inserted through the cassette body. The Allen key engages in a tube nut,
which is turned anticlockwise. Once the tubular nut is undone all the way, it can be withdrawn and the
free hub body removed.
Some clones have the same arrangement, some use an 11mm Allen key from the NGS and a left hand
thread. If you are dealing with a non-Shimano item, check the manufacturer’s literature or website.
For Campagnolo and similar hubs, the cassette body does not need to be removed – in fact, it comes
away with the spindle on removal – but the details of Campagnolo technology, or the information
offered on Campagnolo’s website at www.campagnolo.com is very comprehensive.
Freewheel removal
Older type rear wheels with a screw-on freewheel need to have the freewheel removed before the hub
can be serviced.
You will need an appropriate remover for the freewheel that you have – typically BMX type freewheels
use either a “two dog” or “four dog” pattern, multiple freewheels may use any one of a dozen or so
possibilities. In all cases, it is advisable to clamp the remover in top position (using the wheel nut and a
large washer or other metal plate, or the quick release and a suitable washer or plate in the case of a
QR hub), and to hold the remover in the vice. In this way you can use the whole diameter of the wheel
as leverage to undo the freewheel, which is threaded onto the hub.
Once you have the freewheel moving, don’t forget you will have to undo the fixing of the remove,
otherwise you won’t be able to screw the freewheel all the way off the wheel.
Replacement doesn’t need any tooling, simply grease the threads on the hub and taking care not to
cross thread the freewheel, screw it clockwise onto the hub. Final tightening is done on the bike, using
the fact that pedalling the bike tightens the freewheel onto its threads.
Sprocket removal from freewheels
Whilst this can generally be done, the details of “how to” fall outside the normal range of this document.
Where to find more information
Manufacturer's assembly sheets
Manufacturers help-lines
Manufacturer's have Internet sites where this information can be accessed
Barnett's Manual
Sutherland's manual Handbook for Cycle Mechanics
Zinn and the art of road bike maintenance
Zinn and the art of mountain bike maintenance
48
Module 7 – Tyres and Tubes
Inner Tubes
Purpose
The purpose of the inner tube is to retain air inside the tyre. Most tyres have an inner tube, the
exceptions being “tubeless” types that seal against a specially designed rim, like car and motorcycle
tyres, and some forms of tubular tyre.
Technical Specification
There are two basic materials used to make inner tubes:
Butyl – a synthetic rubber
Latex – a relatively pure, natural form of rubber.
Butyl tubes are sometimes supplied with a self-sealing system. Latex tubes are sometimes covered
with a very fine layer of butyl rubber so that they do not or lose air over a period of time in the way that
a pure latex tube does.
Each material type may be fitted with
one of three types of valves:
Schraeder valve (sometimes
called an American valve)
Presta valve (also known as a
French valve)
Woods valve (now quite rare,
also known as English valve)
The tube must be the correct size for
the tyre, although some flexibility in
the sizing of inner tubes exists, where
there is comparatively little flexibility
in the sizing of tyres, especially
where bead diameter is concerned.
Tyres
Purpose
The purpose of the tyre is to provide a tough envelope around the inner tube, to resist the mechanical
damage that might otherwise befall the tube. In most cases the tyre will also retain the tube against the
rim, the exception being tubeless tyres, where there is no inner tube, and tubular tyres, where the tube
(if present) is sewn inside the tyre and the whole unit is glued or taped to the rim.
Technical specification
A tyre consists of a case, normally composed of a weave of a fabric, held in a flexible matrix. Onto this
is applied a tread, usually of a synthetic rubber like compound, which is simultaneously moulded to
49
shape and vulcanised to the case, to form, in essence, a single piece with the case (although in a very
few instances, the tread is bonded to the case and can be removed). A bead, or ridge, runs all the way
around the two inner circumferences of the tyre, normally made of wire or a flexible but inextensible
material like Kevlar, and moulded into the construction of the tyre – it is this bead that holds most tyres
onto the rim.
Sizing
Tyre sizing is one area that provides many problems, when quoting tyre sizes in different ways. This
relates back to the original system used to size tyres, which relied on a nominal inflated diameter and
profile. The difficulty was one of compatibility. The classic problem was a 26 x 1 3/8 tyre being bought
to fit a 26 x 1 3/4 rim, although they have the same nominal inflated diameter, they are not cross
compatible.
This system was largely replaced by ETRTO (European Tyre and Rim Technical Organisation) and this
system has now been adopted by the ISO (International Organisation for Standardisation).
This standard provides a system for specifying tyre, tube and rim size that guarantees compatibility.
The ISO designation comprises two figures, e.g. 23-622. The first figure relates to the nominal profile of
the tyre, the second is the bead diameter. On the rim this is known as the bead-seat diameter. These
two dimensions reflect far more accurately the true size of the tyre and rim. If the bead diameter and
the bead-seat diameter match, provided the rim specification allows for tyres with the desired profile,
compatibility is guaranteed.
Assembly of tyres and tubes onto the rim
Tools
Tyre levers or quick stick (plastic for alloy rims)
Track pump or stirrup pump, preferably with a built-in pressure gauge
Preparation
Prior to tyre and tube assembly on to the wheel, ensure that the wheel is true and the rim undamaged,
and that the rim is compatible with the type of tyre selected. Some older style rims (Endrick, Westwood
and Westrick) may not suit more recent tyre designs.
Tubeless tyres must be fitted to rims suited to tubeless designs, or modified to be so, whilst tubulars
must be fitted to purpose-made “sprint” rims. Tubeless and tubular designs, and the older style tyres for
Endrick, Westwood and Westrick rims fall outside the scope of this document.
It is important to ensure that there are no spokes protruding through the nipples and into the well of the
rim.
In the case of an eyeleted rim, or a rim where the floor of the rim tape sits against does not also carry
the heads of the spokes (a box section), spokes may protrude slightly through the nipples, although this
is less than ideal wheel building practice.
If a rim tape is already fitted, it should be temporarily removed to ensure no spokes are protruding into
the rim, as this may puncture the tube when inflated. If the rim tape is damaged in any way, or is not
compatible, it should be replaced with one that is compatible with the rim and tyre combination being
used. Ensure that the tape seats correctly.
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The rim should also be carefully inspected. Any sharp edges (usually, but not exclusively, caused by
accident damage) could damage either the tyre wall or the inner tube during fitting or in use. This type
of damage can sometimes be rectified by careful use of wet and dry paper or emery cloth. If the
damage is too severe, there may be no option other than to replace the rim.
Check the tyre for direction of rotation and specificity. Many are designed specifically for use only as
front or rear, and fitting one incorrectly may cause handling difficulties, durability issues and/or
accidents.
The tube must be the right size for the rim and tyre combination in use. If it is too large, it will be difficult
to get the tube into the tyre, and it may be impossible to correctly seat the tyre. If the tube is too small, a
durability issue will almost certainly arise, as the material of the tube will be stressed by expansion to fill
a bigger tyre than that for which it was designed.
Fitting
The rim tape that is fitted must be compatible, correctly centred, and have the valve hole directly in line
with the valve hole in the rim.
Inspect the tyre and tube for any visible damage and replace if any damage is found. It is best generally
to replace all tubes that have a number of puncture repair patches. This inspection should be carried
out even on new tyres and tubes, as they may have been damage in transit or storage.
The tyre, even if new, should be checked for anything lodged in it. The easiest way to do this is with a
close visual check. Some mechanics also run a wad of cotton waste or similar around the inside of the
tyre, which will snag on any small protrusion. Doing so will also clean the inside of the tyre making
inspection easier. DO NOT use your fingers to feel for any protrusions. If glass, a small nail, hard thorn,
or worse, a hypodermic needle or fragment of one is lodged in the tyre, and protruding through it, an
injury might result, with a danger of infection.
The tyre bead should be checked for condition and to ensure that the bead is fully enclosed by an
undamaged layer of tyre casing.
The two beads of the tyre are fitted to the rim separately. Fit the first bead from the drive side of the
rear wheel, with the embossed inflation pressure range adjacent to the valve. This will keep the inner
tube clear of the cassette or freewheel during fitting, reducing the chances of snagging, and thereby
damaging, it.
Lightly inflate the inner tube. At this stage it should no longer be flat but filled out into a round shape. Fit
the valve of the tube through the hole in the rim. Working away from the valve and both ways around
the rim simultaneously, fit the tube into the tyre.
Once the tube is fully run into the tyre, the second bead of the tyre can be fitted, this time starting
opposite the valve and finishing at the valve, or vice versa. The important thing is to work evenly away
from or towards the valve, so that the valve itself stays perpendicular to the rim, and the tube is not
dragged around the diameter of the rim unevenly. With few exceptions tyres should, and can be,
completely fitted by hand. No additional tools should be required. The use of tyre levers and some other
tyre-fitting tools often cause punctures if used in fitting. This will then mean re-doing the job.
Push the valve into the tyre to ensure the seat of the valve and the tube adjacent to it are not trapped
under the tyre bead at this point. This is one of the most common causes for the tyre not seating
correctly, and if not identified and rectified at this stage, the tube may explode when fully inflated.
Check the tyre is seated correctly all the way round. If it is, inflate to 15-20psi (1-1.33bar) and again
check the tyre is seated. If all appears in order, continue to inflate the tyre to the recommended
51
pressure. As this is being done, regularly inspect the seating of the tyre and ensure that the valve
remains straight in the valve hole.
The procedure for the front wheel is the same as that described above, and when the front and rear
wheels are reassembled into the cycle, the front wheel should be oriented so that the label giving tyre
inflation information is on the non-drive side if the bike.
Ensure that the quick-release skewer (if present) is in the bike with the handle on the non-gear side,
and that any computer magnet or similar is on the appropriate side of the wheel to function. Do a final
check on the direction of rotation, if it is marked, to ensure that it is correct.
Removal
Removal of the wheel from the bicycle and the reval of the tyre from the rim are often problematic,
especially for the inexperienced. Here we will deal with the most challenging, the removal of the rear
wheel in a derailleur system bike. Front wheel or single speed wheel removal is far easier.
Process
Put the bike into top gear (the “hardest” gear) at the back and onto the biggest chain ring (if there is
more than one) at the front. Stand on the chain side of the bike, facing backwards, with the bike right
way up. Release the rear brake so that the brake blocks will pass over the tyre without snagging.
Release the wheel nuts or the quick release, and bending over from the waist, use you left hand to
rotate the rear derailleur backwards about its mounting bolt, whilst lifting the bike by the rear derailleur.
Sometimes it is necessary to give the wheel a tap with the heal of your right hand. The wheel should
drop cleanly out.
Lift the bike and wheel clear of each other and, if doing this job by the roadside, lay the bike down on its
non gear (left hand) side, so as to keep the chain and gears clear of any dirt or debris on the ground. In
a workshop, you can hang the bike up by the seat post or saddle at this stage, provided that you can do
so in a fashion that is safe for you and others.
Place your feet about shoulder width apart and place the wheel on them, freewheel towards you and
valve at the top. Grasp the tyre each side of the valve and keeping a sliding but tight grip on the tyre,
rock it from side to side as you push it evenly on both sides away from you, towards the floor, work your
hands around in this way until you can bend no further comfortably, and retaining as much “inward”
pressure on the tyre as you can, flip the wheel up and hold it against one hip. Continue working the tyre
away from the valve, rocking from side to side.
In most cases, by the time you get opposite the valve, you will be able to see daylight between the top
edge of the rim and the bead of the tyre. In this case you can simply roll the tyre away from you, to the
non freewheel side of the wheel and the tyre and tube, with a little gentle persuasion, will come off as a
unit.
If there is no possibility of the tyre coming off so easily, use two lever – one is held hooked under the
bead on the non-freewheel side of the rim, perpendicular to the rim. Trap the heel of that lever under
the palm of your left hand. Use the thumb of that hand to push a section of the tyre wall across, and use
the other hand to insert the second lever. Then turn the heels of both levers simultaneously downward,
and the tyre will release off the rim.
Use the second lever, by turning the wheel-edge on to you and pushing the lever away from you, to
release the tyre from the rim. Mind that you don’t catch your knuckles on the spokes doing this.
The tube can then be removed, via the non freewheel side of the rim, leaving one bead of the tyre in
place.
52
If you are doing any of these operations by the roadside or trailside, avoid direct contact of the bare,
uncushioned rim with any hard or abrasive surface, and avoid allowing the inner tube to drag on the
ground, as it may pick up grit which will puncture it almost as soon as you ride off.
Removal
In cases where the repair of a puncture is being dealt with, inspect the tyre before attempting removal
of tube, for any debris that may have caused the puncture, and remove, if possible. Note the position of
the debris on the tyre in relation to the valve.
Remove the wheel from the cycle and, working opposite the valve on the non-drive side of the wheel,
start to remove the tyre. If the removal is being done on a tyre that is fully or partially inflated, let the
tyre down. Insert two tyre levers under the tyre bead and lever towards the hub.
It is sometimes possible to remove the tyre by hand from this point, and sometimes not. If a third lever
is required, use it, and work the two outermost levers around the tyre until it is loose enough to remove
by hand.
Remove the inner tube and, if punctured, dispose of it in the correct manner. Inspect the inside of the
tyre for any protrusions. This used to be done visually in conjunction with running a wad of cotton waste
across the inner surface. It is worth repeating that, for health and safety reasons, it is better to do only a
close visual inspection as any item that punctured the tyre carcass will at least be sharp and may also
be contaminated.
Maintenance
Tyres should have their inflation pressures checked regularly.
Tyres should also be inspected for cuts, cracks and splits in the tread or sidewall and any other
damage that may cause the tyre to fail prematurely. If there is any doubt concerning the safety of the
tyre. It is recommends that the tyre is replacement.
Inflation pressures
Under British Standards 6102 part 1, 1992, all tyres fitted to bikes sold in the UK, should have the
maximum inflation pressure moulded into the sidewall of the tyre. Failure to inflate to the recommended
pressures may affect control of the bike and cause accidents. If the tyre does not carry this information,
replace it with one that does..
Were to find information
Manufacturers' service or repair manuals
Most Manufacturers have Internet sites where such information may be available
Barnett Manual
Sutherlands Handbook for Bicycle Mechanics
53
Module 8 – Frames
Frame Alignment / Preparation
Purpose
To ensure the frame-set is undamaged and tracked so that:
Compatible parts can be easily and correctly assembled to the frame
The completely assembled cycle is roadworthy and safe to ride
54
Tools
Frame Alignment Gauge
Frame & Fork Alignment Gauge
Derailleur Alignment Gauge (“DAG” tool)
Frame Alignment Stand
Steel Rule
Vemier gauge
Tape measure
Ball of string
Preparation
Cutting lubricants suitable for use with taps, dies and facing / reaming cutters and the
material of the frame
Bottom bracket cutting or chasing taps (as appropriate) of the correct thread specification for
the frame (generally now either BSC or Italian) and a suitable holder. We strongly
recommend the type which has both taps running down a substantial common shaft.
Bottom bracket facing tool and guides suited to the bottom bracket threads (sometimes
integrated with the tools above).
Head tube facing and reaming tool of appropriate specification to suit dimensions of head
tube and headset system.
Crown race facing and reaming tool (in the case of steel or welded alloy forks – do NOT use
in the case of any type of bonded fork).
M3, M4, M5, M^ and M10 x 1 taps and suitable tap holder (note that M10 x 1 is a cycle
specific size, normal M10 taps are generally M10 x 1 is a cycle specific size, normal M10
taps are generally M10 x 1.5 and are not suitable).
In some cases you may need to ream out the seta tube to ensure a clean fit for the seat post
– make sure that you know the correct internal diameter of the seta tube for the frame that
you are working on. In this case, a seat tube reamer will be needed, (do not ream carbon
fibre seat tubes!).
Initial work
If you are going to install equipment to a new frameset you should always inspect it to check for any
possible damage and /or miss-alignment. Fitting components to a damaged or out of track frame
may result in them failing to function correctly and possibly make the finished cycle unsafe to ride.
For older framesets you should also check if there are any signs of accident damage, rippling
around head tube and or top tube, for example, and corrosion.
Flaking paint may point towards corrosion. Be aware that modern frame tubing is very thin and
exposure to corrosion will rapidly reduce the tube thickness ultimately leading to holes in the frame
and complete failure. THIS SHOULD BE AVOIDED AT ALL COSTS.
Before commencing the preparation of the frame, or installation of any component onto a cycle
frame that has already been prepared at the factory, it is always important to carry out the following
checks and procedures. If the frame has yet to be prepared, making these checks before you begin
work will save you, in cases where the frame is, in some way described below defective, a measure
of time & wear and tear on the tools and waste of lubricant materials.
55
Carrying out these checks on a factory prepared frame is just as important as it may save you time
further down the line in the building / repair process.
If the frame has been prepared at the factory, you should check that such work has been correctly
carried out AFTER you have looked at the items below.
Frame, Rear Triangle and Fork Alignment
Where you are dealing with a new frame, the frame and fork should be inspected for damage as the
packaging is removed, and any signs of it reported immediately. In the case of a frame that has
been previously used, an overall visual check should also be carried out.
Visually check the integrity of the joins in the tubes, paying particular attention to the junction of the
head and down tubes at the head tube. Where there is a visible weld, check that the weld bead is
continuous all the way around, with no areas unwelded. In a lugged and braised joint, as far as is
possible, try to check that there is brazing material (typically a brass alloy) all the way around
between lug and tube – there will be a gap (although this is sometimes filled or hidden by
paint)where the brass is missing.
In carbon frames, it is almost impossible to tell whether the joints in the frame are good, the surface
layer of carbon may hide a multitude of sins. You can look to make sure that where alloy parts are
bonded to carbon, however (fork ends, rear ends, rear triangle elements bonded to alloy front
triangles, or front triangle elements bonded to alloy elements, etc) that the bond looks solid.
The frame should be securely held in the stand so that further checks can be made. Some tubes
may easily be crimped if clamped directly into the stand so Manufacturers instructions should be
referred to, to ensure the frame is not damaged during its visit to your workshop. In general we
would recommend that a seat pin of the right diameter be fitted and clamped in place, and the seat
pin used to clamp the frame in the workstand. If the seat tube needs to be reamed out to allow a
seat post of the correct diameter to be fitted, then do this now, making absolutely sure that you
know what size the seat tube should be internally. Don’t guess, check!
Once the frame is in the stand, use the frame alignment gauge to check that the rear dropouts are
of equal distance from the centre of the frame. Use the frame alignment gauge to check that the
rear dropouts are of equal distance from the centre of the frame. Use the frame alignment gauge to
assess twists in bends in the frame tubing.
If you do not have access to a frame alignment gauge, as fig.8.2, the use of strong thread can
assist in identifying tracking problems. Measuring, to ensure 'a' = 'b' and cc' = cd'.
Figure 8.2
56
Using either the vernier gauge or the steel ruler, check the distance between the inside surface of
the rear ends is correct for the type / age / intended build of frame – as a general guide:
Road frames for derailleur gear
o Old 5 and “Ultra” 6 speed frames – 120mm
o “Standard” 6 and 7 speed frames – 126mm
o 8, 9 and 10 speed frames – 130mm
Bear in mind that rear wheels can be respaced so that older types of, say, 5 or 6 speed
wheels can fit into modern 130mm rear end frames
Track and some single speed frames
o Dedicated track frames – generally 120mm, very old ones may be 110mm
o Some modern frames built for single speed or geared use – 130mm or 135mm
Mountain bike and hybrid frames
o Generally 135mm
Tandems
o For off road use 135mm or 140mm
o For road use may be 126 (if very old), 130mm, 135mm or 140mm
o For dedicated track use – 120mm
If you find something unexpected, refer to the frame manufacturer, and if the frame is used and you
are carrying out a repair, or looking at a custom build, also check the rear wheel (if present) – either
manufacturers or end-users might have modified the above dimensions, especially where the frame
or the equipment have been customised to a particular purpose.
Front drop outs in general should be 100mm from inside surface to inside surface, although there
are examples of forks designed for 120mm Over-Lock-Nut (OLN) dimension wheels, and some
older special purpose forks have also been built to accommodate 80mm OLN hubs.
Having checked the spacing on the frame and fork ends, use fork end alignment tools to check that
the fork ends are parallel to each other.
The tool shown above is more elaborate than many, but
works in the same way – the two “halves” of the tool are
set at the correct distance (depending on the frame or
fork being checked), and the tools are fixed home, fully
engaged in the dropout.
The cup shaped parts should come cleanly face to face,
correctly aligned with each other in three dimensions. If
they don’t, the dropouts / fork ends that you are
examining are out of alignment.
Figure 8.3 Dropout alignment tools in
use
On steel frames, and some alloy frames, it is possible to
re-align the dropouts – the tools are designed to be used
as levers to cold-set the dropouts into place.
DO NOT try to do this on carbon frames / forks, or on suspension forks.
57
If you are in any doubt at all, contact the frame manufacturer or distributor…it is better to delay a
day or two than to break or irreversibly damage a frame!
Tapping of threads, facing of bottom bracket & head tube, facing & milling of fork
crown
IMPORTANT – Do not try to tap out, ream, mill or face titanium frames…at best you will blunt the
tools and at worst may actually get them irrevocably jammed in the work due to the titanium
“galling”.
Before undertaking these operations, you will need to establish:
The thread type of the bottom bracket (BSC, Italian, French, etc)
The type of BB to be fitted (traditional, sealed unit, outboard)
The type and specification of headset to be fitted (threaded or thread less – JIS or ISO, semi
integrated, integrated)
The frame material and any special requirements with regard to cutting / tapping lubricants
General
It is generally a good idea to ream out the seat tube, if it needs doing, as the first frame preparation
operation. This allows you to set a seat post or dummy seat post in place to clamp the frame in the
work stand whilst you work on the frame, and means that swarf from cleaning the seat tube will be
cleared from the frame at the same time as swarf is cleaned out of the bracket shell following facing
/ chasing operations.
Bottom bracket thread sizes are covered in Module 3 – Bottom brackets, as are the various types of
bottom bracket.
In terms of facing operations, in the case of a traditional bottom bracket, you’ll need to face off both
sides of the bottom bracket shell after you have chased the threads out. This is also true in the case
of an outboard cup type system.
In the case of a cartridge unit, if only one cup has a flange that will come up against the outside
surface of the bottom bracket shell, then only the side that cups fits needs to be faced. The other
side can be left alone, the paint providing a barrier against corrosion.
Make sure that the forks are suitable for the type of headset that you intend to fit.
Headset specifications are covered in Module 5, as are the various types of headsets.
To fit a thread less headset you need to have a plain column fork without any threads on the top of
the column, with a column length adequate for the stack height of the headset, the number of
spacers required, and the depth of the stem you intend to fit.
In the case of a threaded headset, the threaded portion needs to be long enough to accommodate
the stack height of the headset in combination with the length of the head tube of the frame (see
Module 5).
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DO NOT fit a thread less headset assembly to a bicycle with a threaded fork column, even if it looks
as if there is enough fork column available to do so – the columns are different and not
interchangeable.
Tapping out and facing the bottom bracket shell
This operation is carried out to ensure that the threads in the bottom bracket are concentric, aligned
with each other, and that the external faces of the bottom bracket shell are parallel and
perpendicular to the axis of the threads. These conditions need to be met for the correct function of
any bottom bracket fitted, but are of greatest importance in the case of traditional cup and axle
bottom brackets, and outboard cup systems.
Whatever type of bottom bracket is fitted, chasing out the bottom bracket threads will make fitting of
the BB unit a much easier operation.
Make sure that there are no cut ends of tube protruding into the bottom bracket area of the frame
that might either make it difficult or impossible to align the bottom bracket taps into the bracket. If
there is a screw or rivet holding a bottom bracket cable guide in place that protrudes into the shell,
remove it so that it can’t interfere with tools inserted into the BB shell.
You can carefully file away any obstruction (typically the ends of the chain stays or the base of the
seat or down tube) that protrude into the BB shell. Don’t worry too much if you catch the threads
occasionally with the file, as when you chase the threads out, this will rectify the
damage…obviously, make as much effort as you can not to damage the threads, though.
Once you are satisfied that the BB shell is clear of all obstructions, and that you are sure that you
know which thread specification you are dealing with and that you have the correct tools to work on
it, offer up the thread chasing tools to the work.
Remember that there are two different marking conventions to identify the left hand thread tap…”L”
stamped on the tool may mark the left hand thread, or it may refer to the left hand side of the bike.
Ensure that you get the taps round the right way when you insert them into the frame initially. You
can determine LH or RH thread by looking at the tap sideways on with its axis vertical, narrow end
uppermost – if the cutting surfaces “slope” top left to bottom right, this is LEFT HAND THREADED.
If the slope is the other way, this is RIGHT HAND THREADED. For your own set, it is worth
engraving an extra tell-tale on the body of the tap. Don’t try and stamp it in – dremmel with a
diamond burr or similar, to mark the body of the tap itself.
Once the taps are offered up to the work, lubricate thoroughly with a suitable cutting oil or paste for
the material you are dealing with, generally a low sulphur oil like “Tapmatic” or Weldtite cutting
paste.
Turn the taps into the work, ensuring that you screw “in” a full turn at the most, then back “out” a
quarter to half a turn, repeating on each side until the taps are fully into the BB shell.
If you have the type of bottom bracket tool where the facing tools are integrated with the taps, then
lubricate the facing cutters and bring them into contact with the BB shell now. Tighten the tension
spring so that the cutters give a smooth cut with no “chatter”.
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Figure 8.4 Bottom Bracket Cutting and Facing
Tool
Figure 8.3 Chasing and Facing Set
If you have a non integrated type of tool, you will find that to face the BB, you’ll have to remove the
BB thread chasers from the work. A guide for the facing tool usually screws into each side of the BB
shell in their place.
When facing, face one or both sides of the shell according to the type of bracket that you are fitting,
only turning the cutters IN THE DIRECTION OF THE CUT. Don’t back them off as you would a tap,
you will blunt them. Take only as much material off the BB shell as you absolutely need to, to get a
flat, even face all the way. Do not cut into the margin of any welds in the BB area.
It is better to repeatedly remove a small amount of material, back the tool away from the work and
review progress, then continue of necessary, than to rush in too gung-ho and remove more material
than you need to or too much material. You can always cut more off, but you can’t put it back on if
you remove too much!
In the case of a nominal 68mm BSC BB shell, do not cut to a width of less than 67.5mm (72.5mm in
the case of a nominal 73mm shell), or in the case of a 70mm Italian shell, do not cut to a width less
than 69.5mm.
Once you are happy with the work done on the BB, remove the tool and clean it. We recommend
that you blow the swarf out of the BB shell with an airline or similar – take appropriate precautions
to avoid getting swarf in your eyes. If you use a brush or cloth to remove swarf, be careful – the
swarf is small and can be razor sharp!
Reaming and facing the head tube
This operation is carried out so that the bores or seats in the head tube top and bottom are
concentric and of the correct diameter or form for the headset being fitted. It also ensures that top
and bottom faces of the head tube are parallel and perpendicular to the bore.
You must select a head reaming and facing tool that is correct for the headset being fitted – in the
case of a conventional threaded or thread less headset, you’ll need to know if it is 1” or 1 1/8”
nominal (in any case this is dictated by the frame and fork) and whether it is ISO or JIS. For semi
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integrated and integrated headsets, you will need to know the exact specification of the headset
and make sure that you have appropriate tooling – there is a gauge which helps with this, if you are
presented with a frame and don’t know what headset the frame was designed for, or a set of
bearings and you want to know what they fit.
Figure 8.5 Headset gauge
Reference to the manufacturer’s literature is also of course very helpful, especially with increasing
numbers of manufacturers adopting proprietary solutions.
Once you have established which headset is being fitted and that you have a frame, forks and
tooling that suits the choice, then you can go ahead and ream / mill / face the head tube.
The reaming / milling and facing cutters may mill / ream and face both top and bottom at the same
time, or may need you to undertake the operation on the top end of the head tube, then take the
tool out and repeat the operation from the bottom end, as illustrated in figure 8.6.
In this, latter case, the tool is usually held
centered by a conical guide which fits into
the end of the head tube not being worked
on.
Figure 8.6 Facing and reaming the head tube.
Notice the spring assembly on the cutter guide
to help give even pressure. Different tools to
suit different headsets can usually be mounted
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on the same guide
Assemble the tool into the head tube
according to the tool manufacturer’s
recommendations, ensure that the cutting
surfaces are liberally lubricated with the
appropriate cutting lubricant for the
material, and tighten the tension spring so
that you get a smooth, even cut with no
“chatter” from the tool. As with the
machining the bottom bracket shell, only
turn the tool in the direction of the cut.
Also as with BB machining, take just enough material, no more, and avoid cutting into weld
margins.
Once the head tube is milled / reamed and faced, remove the tool and clean it, then blow the swarf
out of the head tube, exercising caution, as when dealing with the BB.
Milling and facing the fork crown
This operation is carried out so that the fork crown race is an accurate interference fit on its seat,
and sits both concentric with and perpendicular to, the fork column. IMPORTANT: This operation
can only be carried out on welded or brazed steel forks, or on welded aluminum alloy forks. It
should NOT be carried on bonded or carbon forks.
You must select a facing / milling tool that is correct for the headset being fitted – in the case of a
conventional threaded or thread less headset, you’ll need to know if its 1”, or 1 1/8” nominal (in any
case this is dictated by the frame and fork) and whether it is ISO or JIS. In the case of an integrated
headset, you will need to know if the crown race seat (as in these cases what you are assembling
to the fork will generally be a support or seat for a sealed cartridge bearing) has an ISO or JIS
internal; diameter.
Occasionally with all types of headset featuring a sealed cartridge bearing, you may find that the
fork crown race has a split in it, so that the same crown race will be a sprung push fit onto either
ISO or JIS – dimensioned forks.
You may also find a pre-formed or machined taper on some forks, designed to support a sealed
cartridge bearing.
Assemble the tool into the fork column according to the tool
manufacturer’s recommendations, ensure that the cutting
surfaces are liberally lubricated with the appropriate cutting
lubricant for the material, and tighten the tension spring so that
you get a smooth, even cut with no “chatter” from the tool. As
with the machining the head tube, only turn the tool in the
direction of the cut.
Also as with the machining of the head tube, take just enough
material, no more.
Once the fork crown is milled and faced, remove the tool and
clean it, then blow the swarf off, exercising caution, as
when dealing with the BB and head tube.
Figure 8.7 Fork crown facing tool. The cutter
both sets the diameter of the seat and faces
Once these operations are complete, the headset can
the crown off flat
be fitted, following the frame manufacturers
recommendations with regards to materials used to
seat the headset components into the frame and onto the fork crown.
Reaming the seat tube
DO NOT attempt seat tube reaming operations on carbon fibre frames, even if they have an
aluminum insert bonded into the carbon of the seat tube.
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In most cases this is not required for “normal” frame preparation.
Before starting seat tube reaming operations, ensure that you know what size the internal diameter
of the seat tube should be…within very tight limits it is possible to resize the internal diameter of the
seat tube, but in general, seeking the advice of the frame manufacturer before undertaking such
operations is a very good idea.
It is essential that the seat tube reamer goes into the seta tube accurately aligned with the tube so
that material is taken off inside of the seat tube evenly and concentrically.
The normal reason for reaming the inside of the seta tube is more a matter of cleaning it up so that
the seat post fits the frame cleanly, rather than to fit a seat post of greater diameter than that
intended by the frame manufacturer.
Seat tube reamers come in two basic formats:
Fixed diameter
Expanding
In general, if you are cleaning out a seat tube so that a seat post will fit easily and cleanly, then
fixed diameter reamer would normally be used.
Seat tube reamers do have a propensity for getting jammed, so make sure that the reamer is sharp,
undamaged, and correctly lubricated to reduce the risk of this occurring.
If you are resizing an existing seat tube, or if you are cleaning out the debris from a seat post that
has seized into the seat tube, for instance, then an expanding reamer might be more appropriate.
Use of an expanding reamer in these types of application is a very skilled business and probably
falls outside the scope of this document.
The rules for using a fixed diameter reamer are
fundamentally the same as those for reaming a head tube:
Before inserting the reamer, make sure that the
depth you will need to ream. bearing in mind that the
reamer is tapered and the tip of the tool will finish up
below the lowest point that will have been cleaned to the
correct diameter…beware of bottle cage bosses, for
instance on small frames
Ensure that the reamer is lubricated with the
correct lubricant for the material of the frame…lubricate
Figure 8.8 Fixed size
generously as the cutting surface that is engaged is quite long,
seat post reamer
so friction will be high, and it is important that the reamer turns
smoothly in order to get a clean cut and also, if the reamer starts
to “chatter” in the cut, the potential for it to run off line and loose alignment and concentricity
is increased
The reamer should be turned only in the direction of the cut (usually clockwise)
Only remove as much material as is essential for the job in hand.
Once the seat tube has been reamed, the seat post can be fitted, using an appropriate barrier
against corrosion between the frame and seat post – follow the frame makers recommendations.
Generally carbon seat posts are best prepared with a carbon gripping paste, regardless of the
material of the frame.
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Where two metals are involved, a barrier of synthetic waterproof grease can be use, copper slip or
copper grease being a viable alternative.
Aligning the rear hanger
The rear gear hanger should be aligned in accordance with the gear manufacturer’s specification. In
most cases, this is parallel in both the vertical and horizontal planes with the cassette sprockets.
Most recent frames tend to have removable hangers, and such parts are regarded as being
sacrificial in the event of a trauma to the rear derailleur…they are designed to break or deform, and
in doing so prevent damage to the rear gear (in the case of minor knocks) or damage to the frame
in the case of more extreme incidents.
Before attempting alignment of a rear hanger, ensure:
The hanger is the correct pattern for the frame (there are many, many different patterns)
That the rear hanger is tightly fixed by its fixing bolt
The rear wheel that you will use as an aid to the operation is of the right over locknut (OLN)
dimension for the frame. The wheel needs to be true, and it needs to have a correctly
adjusted hub.
Where a hanger’s alignment has been repeatedly “tweaked” in the past, some hardening and
embrittlement may occur.
Bear in mind, therefore, especially if you don’t know the history of the frame:
Repeated straightening of the hanger may cause it to fail. Before attempting to realign a
hanger and if at all possible, make sure you have access to a spare!
Hangers can be bent, especially after a crash, to a point where it is not possible to
straighten them. Broadly speaking, if the surface of the hanger that should be in contact with
the dropout is not fully in contact with the dropout after straightening, remove the hanger
and replace it.
If you see any signs at all of cracking of the hanger when straightening it, remove and
replace it.
Even brand new hangers on brand new frames more often than not need attention. It takes
a few seconds to check alignment and it can save you a lot of time in trying to get good
derailleur adjustment later – take those few seconds!
Hanger failure whilst the bike is being ridden in general equals a big bill – so be careful!
Hanger alignment is carried out with a hanger alignment too (DAG tool).
The sequence of operation is:
Set the rear wheel in the rear drop outs and put bike on the ground. This helps make sure
that the rear wheel is all the way “home” in the dropouts. Tighten the QR and replace the
frame into the stand.
At this point you can, assuming the wheel is accurately true and “in dish”, you can just
quickly double-check that the dropouts are correctly aligned & that the frame is in
alignment…
o If the wheel is fully located in the rear dropouts, it should (in a normal frame) sit
equidistant from both chain and both seat stays
o If it appears to be “off “to the same side, the rear of the frame is out of track
o If the error is repeated but on the other side, the wheel is out of dish. In the former
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case, go back and recheck the frame alignment. In the latter, it’s not a problem for
hanger alignment, so long as the wheel is true.
o If the wheel is off to the left, say, at the chain stay and off to the right (or centered) at
the seat stays, check that it is all the way home in the dropouts, and that there is no
paint preventing the wheel from locating fully.
If the above check gives no problem (and if the previous steps in frame alignment have
been completed correctly, you should have no problem), then fix the Derailleur Alignment
Gauge (DAG) in place in the dropout, as per the manufacturers instructions.
There is generally a small amount of “play” in the measuring arm of a DAG tool – decide at
this point whether you are going to regard gentle axial pressure towards the wheel, or gentle
axial pressure away from the wheel as your norm when performing measurements for this
job – you’ll note that this pressure can cause a movement of several millimeters at the
measuring point – a greater error than you want to accommodate.
Starting at the top of the wheel, bring the measuring point of the tool into contact with the rim
so that it just brushes it, and fix the measuring point in place on its axial travel.
Rotate the tool to the bottom of the wheel, and see if the point tries to overlap the rim, or if
there is a gap between point and rim – you’ll need to move the point down the tool to
establish this. Be careful not to disturb the distance setting.
If the point overlaps the rim, the hanger is bent “inwards” at the gear end. Use the tool to
gently bend the dropout away from the wheel. You only need to move the pointer half the
distance it overlaps the rim. If there is a gap between rim and pointer, you need to bend the
dropout towards the rim; you only need to move the dropout enough to correct half the gap
between pointer and rim.
Run the pointer back up to the top of the wheel, reset the pointer and recheck at the bottom
of the rim. It should just touch in both places. You may need to re-adjust a couple of times,
but bear in mind the comments about repeatedly bending a dropout.
Run the pointer to the mid-point between top and bottom of the rim (the “back” of the wheel)
and check here, too. All three points should be more-or-less in agreement with each other –
an error of 1 or 2mm maximum is usually fine, though. If needs be, correct the horizontal
alignment. You’ll usually find that this introduces an error in the vertical, so you’ll need to
gently tweak things until all three points are more or less in a common plane. You don’t
need to check the “front” of the wheel, as three points define a plane and the dropout will
now be parallel on both axes to the wheel, and therefore to the cassette or freewheel when
mounted.
Where to find more information
Manufacturers assembly sheets
Manufacturers helpline
Manufacturers websites
Barnetts manual
Sutherlands handbook for cycle mechanics
Call Velotech cycling Ltd
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