Version 6.1 - Seven Cycles

Version 6.1
Technical Supplement
T
oday, more than ever, there are hundreds of material variations, fabrication methods, and construction techniques available to bicycle builders. All of
these options have a significant effect on a bicycle
frame's ride characteristics, overall strength, long-term
performance, and ultimately, your enjoyment of the
sport. The following overview touches upon some of
the differences in these options, and discusses
Seven's approach to material usage and framebuilding.
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metallic element. Only aluminum, magnesium, and iron
are more plentiful.
Nonetheless, titanium is never found in its pure form in
the environment. Instead, the metal must be extracted
from other compounds, such as rutile ore and ilmenite.
This extraction process is difficult and expensive, and
is one of the reasons why titanium, and therefore titanium tubing, is so costly.
The first step in the purification process is to create
titanium sponge, named for its sponge-like appearance. Titanium dioxide—which also happens to be
found in all kinds of white substances like paint, M&M
candy prints, and donut fillings—is first mixed with
coke; the mixture is then charged in a chlorinator.
Titanium tetrachloride—or "tickle"—results when the
ore reacts with the chlorine.
Frame Material
Overview
The tickle, a colorless liquid, is purified through fractional distillation then mixed with powdered magnesium. The brew is placed in a sealed container, void of
oxygen and hydrogen, and heated up until the magnesium has reacted with the chlorine. This produces
magnesium chloride and sought-after deposits of pure
titanium, known as titanium sponge.
The sponge is compressed by enormous hydraulic
presses into large pieces of titanium, referred to as
compacts. The compacts are then TIG-welded together, end to end, to form a consumable electrode,
weighing more than 25,000 lbs.
TITANIUM
A bicycle frame represents an ideal application for
titanium tubing. The material's light weight, tunability,
and durability—two times that of steel—allow the
builder to impart a lively, plush ride to the frame,
while maintaining excellent drivetrain efficiency and
torsional stiffness. Working with titanium requires a
great deal of expertise. Although titanium is not rare,
it is expensive, primarily because processing the element is so costly.
The pure titanium is alloyed at this stage, as well. 3Al2.5V titanium, the material from which most titanium
frames are manufactured, is created by adding 3%
aluminum and 2.5% vanadium to the titanium.
The electrode, which is about one meter in diameter, is
placed in a consumable electrode vacuum arc furnace
to create a molten pool of titanium. Then, it is allowed
to solidify in the furnace. The furnace has a copper lining for protection from the titanium, but because the
copper lining of the furnace becomes attached to the
titanium when frozen, it is removed along with the titanium. Using a large lathe, the copper is then separated from the ingot.
Titanium Production
Titanium is available all over the world, although many
people believe that the element titanium is extremely
rare. Actually, it is the earth's fourth most abundant
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The titanium is now steps away from becoming tubing.
But before it does, the ingot is reduced by an oversized forge. This forge is specifically designed for titanium, since titanium can't be forged in the presence of
oxygen. While in the forge, the ingot is continuously
hammered and annealed. Annealing is the process of
heating and cooling at a controlled rate, and is used
for many purposes, including removing work hardening and embrittlement. The process is repeated until
the ingot becomes a bar measuring approximately 8"
in diameter, the proper size to fit through the hole of
the impact extrusion machine. The impact extrusion
machine (actually a combination of a forge and an
extrusion machine) is used to make bar stock into tubing.
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1. It lowers the strength of the tube to prepare it for
the pilger mill (rocking). Titanium work hardens;
thus, when the tube is run through the pilger mill,
the tube's strength increases dramatically. As a
result, the titanium becomes much harder and
tougher and would damage the pilger were it not
first vacuum annealed.
2. It makes the tube malleable (relieves stress) so that
it can run through the pilger mill. This dramatically
increases the tube's ductility without causing it to
further lose strength. Were the tube not ductile, it
would be very brittle and more likely to fail. It would
also be much more difficult to machine and bend.
Since the stress reduction that occurs during annealing can also cause the tube to bend or bow, the tube
is straightened before continuing through the process.
Manufacturing Titanium Tubing
The fabrication of titanium tubing requires special
equipment and an oxygen-free environment.
Depending upon how stringent the specifications for
the tubing's size and weight, purity, straightness,
molecular grain orientation, surface finish, and the
presence or lack of surface defects, titanium tubing
can cost nearly $60 per foot.
Pickled once again, the tube is then tested ultrasonically to detect any flaws—chemical or otherwise—that
could create a problem during pilgering.
The pilger mill consists of an internal mandrel that supports the inside of the tube, and large rollers through
which the tube rolls. During rocking, the hollow is
squeezed, rolled, and hammered to reduce the diameter of the tube and make the tube wall thinner. The
tube is actually pilgered several times. Some passes
through the pilger mill focus on reducing the tube's
diameter, while others emphasize reduction of the
tube's wall thickness.
The 8" titanium bar that is created from hammering
and annealing during the manufacture of titanium is at
last fed into an impact extrusion machine. An enormous hydraulic cylinder drives the bar into one end of
the machine to create an extremely hot tube, measuring approximately 45' in length. The tube is immediately immersed in a tub of hydrochloric acid to remove
its superfluous outer layer.
The repeated pilgering is performed as part of a
sequence that also includes pickling, annealing,
straightening, and ultrasonic testing, until the proper
tube size and grain structure are achieved.
The machine draws the oversized tubes down in size
to create a tube hollow. But the tubing still isn't in a
usable form. The tube hollow is shipped to a tubing
mill, where the titanium is transformed into tubing.
When the tube hollow arrives at the mill, it is weighed
and inspected both visually and dimensionally. The
hollow is also subjected to a chemical analysis to verify that the tube meets the mill's certification for purity
requirements. Once the tube passes those tests, the
hollow is cleaned and pickled (acid etched) to remove
any oxidization or residual scale (also known as alpha
case) and is ready for vacuum annealing.
Grain structure is determined by the ratio of the rate at
which the tube's diameter is reduced to the rate of
reduction of the wall. Grain, or texture, is tested by
measuring the contractile strain ratio (CSR) of the
tube. A CSR from 1.7 to 1.9 promotes the highest
fatigue strength possible, while maintaining excellent
bending characteristics. A CSR above 2.0 improves
bending, but decreases fatigue endurance dramatically. Since optimal CSR is controlled and determined at
the mill, cold working (i.e., tapering or internal butting)
the titanium tubing after it leaves the mill can detrimentally affect the endurance of the tube.
Vacuum annealing is a critical step in the manufacture
of titanium tubing for two important reasons:
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as molecular grain orientation; interior and exterior surface finish; and the presence or lack of surface and
chemical defects.
The tube's texture must be optimized to obtain the
highest fatigue strength possible. Similarly, a smooth,
defect-free surface also contributes to longer fatigue
life.
Types of Titanium
In addition to unalloyed titanium, which is called commercially pure or CP, there are two alloys commonly
used in the cycling industry today: 3AL-2.5V and 6AL4V.
3AL-2.5V
3-2.5 titanium is an alloy consisting of 3% aluminum,
2.5% vanadium, and 94.5% pure titanium. The properties critical to bicycle tubing are best served by a
high quality 3-2.5 seamless tube. Excellent fatigue life,
property consistency, form-ability, and corrosion resistance are but a few of the reasons 3-2.5 is still the premier frame material.
Once the optimal wall, diameter, and grain structure
have been achieved, the tube is pickled again to
remove any scale or debris from the pilgering process.
A final anneal to accomplish a partial stress relief follows this step. The mill's goal is to achieve a delicate
balance of ductility and strength; thus, this round of
annealing slightly reduces the strength of the tube,
while making it more workable for the end user.
In the U.S., bicycle frames are commonly manufactured using 3-2.5 certified to either an ASTM B-338 or
a sports grade specification. ASTM B-338 meets all
Aerospace Material Specifications for hydraulic tubing.
Sports grade, certified according to a less stringent
set of chemical and mechanical specifications, is typically less expensive.
One last acid etching of both the inside and outside of
the tube follows, since vacuum annealing can leave
oxidation or alpha case. This final pickle also imparts a
perfect finish. While this is not standard for sports
grade titanium tubing, Seven specifically requests this
final finish on its titanium tubing.
Some builders may use surplus material or "scrap",
which meets neither aerospace nor sports grade
specifications. Certification is not available for scrap,
making it impossible to determine whether the material
is of inferior quality.
Before the tubing can be boxed up and shipped out, it
goes through a series of rigorous tests: eddy current
or ultrasonic testing; visual and dimensional inspection; and a final quality control certification.
6AL-4V
Titanium Quality
The quality and strength of titanium tubing varies just
as it does for steel tubing, depending upon the source
of the material. The key to tubing quality lies in processing, which plays a critical role in determining the
structural integrity—and therefore the longevity—of the
final product. During processing, three variables affect
the final quality of a titanium tube: texture, also known
An alloy of 6% aluminum, 4% vanadium, and 90% titanium, 6-4 titanium offers some very favorable raw
material properties, which is why Seven uses it to fabricate dropouts and other frame parts. One of the
properties that makes 6-4 an optimal material for
dropouts is its toughness. But this toughness also
makes it unattractive as a material from which to make
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building, which requires a very wide variety of tubing to
ensure optimum ride characteristics. In addition,
external butting is preferred to internal butting for the
reasons outlined in the Tube Butting Processes section of this document, under Manufacturing Overview.
tubing. Applying the techniques used to draw 3-2.5
tubing to 6-4 tubing costs much more and wears tooling very quickly. In addition, tube wall consistency,
concentricity, and finish quality—both inside and outside—are limited. At the time of this printing, no U.S.
mill offers seamless 6-4 tubing. However, some do
offer 6-4 seamed, or welded, tubing.
One might argue that the strategic use of the limited
6-4 tube sizes available in combination with 3-2.5
tubes would create a better bike. But there is no
weight advantage for bikes currently employing 6-4
tubes over the top-of-the-line 3-2.5 bikes available.
And there is no appreciable stiffness or strength benefit either, since 6-4's higher bending stiffness is offset
by its lower torsional stiffness, and the butting techniques employed in the 6-4 tubes currently available
have a negative impact on fatigue strength. So, 6-4
only adds expense.
Two major issues prevent Seven Cycles from favoring
this method of tube manufacture. First, seamed tubing
is fabricated by rolling 6-4 sheet into a tube shape
while simultaneously welding the seam that is created
in the rolling process. The result is a tube that has a
welded seam—a potential failure point—along its
length. This seam acts as both a hard point and a
stress riser since the weld bead is thicker than the
tube itself and the weld creates an inconsistency in the
tube.
CP
Second, 6-4 sheet is designed to be used as a sheet,
not as a tube. If it is formed into a tube, its grain structure can lead to premature tube failure. Indeed, a 6-4
tube will fail through fatigue cycling (repeated flexing)
before it should, and independent fatigue tests show
that tubing made from 6-4 sheet does not have the
fatigue life of a properly drawn 3-2.5 tube.
A small number of titanium frame builders incorporate
Commercially Pure (CP) titanium into their frames. CP
has, at best, half the strength of 3-2.5. A CP frame
must be made heavier than an equivalent 3-2.5 frame
in order to have comparable strength. Even most
steels used in high quality frames have higher strength
than CP. The overall quality of CP tubing is lower
because it is typically used in low-cost applications—
not bicycle building. CP is used mainly in industrial
applications when corrosion resistance is most important.
In recent years, some seamless 6-4 tubing has trickled
into the bike industry from outside the U.S. However, it
is only being offered as a few internally-butted tube
lengths of limited sizes (as determined by tube diameter, wall thickness, and butting placement). These limited offerings are inadequate for modern high-end bike
Tough to Beat 3-2.5
Historically, aerospace and defense industries have
driven materials technology, and 3-2.5 continues to be
the Ti alloy of choice. At present, these industries are
not clamoring for 6-4 tubing, which is why no U.S. mill
is producing it. For there to one day be an ample
supply of 6-4 tubing in a wide array of sizes and at a
reasonable price, it will take the interest and purchasing power of an industry much bigger than the bike
business. Though this may be on the horizon, there's
no indication that it will happen any time soon.
In addition, an examination of some other high-tech
industries that depend on high strength alloys like 32.5 and 6-4 reveals that none use 6-4 small diameter
tubing, primarily for the reasons mentioned above.
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Technical Supplement
Consultation with titanium mills tells us that commercially available seamless 6-4 in a variety of sizes is not
on the near horizon.
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turing carbon fiber tubing. The tubular structure
that results from the process has no seams, stress
risers, or imperfections that might cause a tube to
fail.
CARBON FIBER
3.Fatigue Life: The majority of carbon tube failures
are caused by voids in the tube's resin structure.
The CNC-controlled winding process minimizes
stress risers—porosity (oxygen pockets) and
voids—and does not provide an opportunity for
fatigue life to be compromised. The proprietary
resin used in Seven's Elium and Odonata models
improves fatigue life, too, by bettering the tube's
elongation properties and minimizing porosity.
The term "carbon fiber" refers to a wide range of
materials, including carbon, e-glass, and s-glass. It is
difficult to generalize when discussing carbon. There
are many ways to make
carbon fiber tubing, and
variations in weave orientation and fiber
choice make one carbon tube very different
from another. Also,
there is a wide disparity
in the quality of tubing
among manufacturers.
4.Tunability: Filament winding allows for total control
over fiber orientation, and therefore creates truly
anisotropic, or directional, tube properties. For
example, we can make the tube stiff in bending but
relatively compliant in torsion. This means that
Seven has the ability to tune the bike's ride quality
to an extent not available with isotropic tubes, or
tubes with properties like titanium, steel, or aluminum.
Filament Wound Carbon Fiber
Filament winding is a process used to fabricate high
quality, super-consistent, low void, seamless, composite tubing. The two ingredients—continuous composite
filaments and epoxy resin—are "wetted out", or preresined, and then wound together in tension for maximum strength and consistency. During winding, an
internal mandrel maintains extremely accurate inside
diameters and surface finishes in every tube. After
winding, the tube is cured for maximum strength, and
the outside diameter sized to an exact tolerance.
STEEL
The predecessors to today’s steel frames were first
produced in the 50’s. Technology has not changed
much since then, and the ride of a steel frame is still
the standard by which all other bicycle frames are
judged. Steel can be described in general terms as
lively, solid, and predictable. Steel's durability and
tunability make it a favorite of many cyclists.
Filament wound carbon is superior to carbon manufactured by other common methods for four important
reasons:
The steel tubing used by bicycle frame manufacturers
typically falls into one of three basic categories:
microalloy; heat treated cromoly; or standard 4130.
1. Strength: Filament wound carbon tubes exhibit the
highest strength of any carbon tubes. Seven's carbon tube set consists of tubes fabricated in tension
on computer numerically controlled (CNC) equipment, using continuous fibers that have a tensile
strength greater than 700,000 psi. Without break
points to allow for discontinuous or inconsistent
properties, continuous fibers optimize strength.
Microalloys include Columbus Foco™; Reynolds 853™;
True Temper HOX Gold™; and Dedacciai Zero™ tube
sets. Microalloys are unique in that they become
stronger after welding due to air hardening. This
means the tube itself gains strength, and its fatigue life
enhanced. In addition, the tube fabricator can make
the tube thinner and thus lighter. These are the
lightest, yet strongest, steel tubes. Generally speaking,
the ultimate strength of microalloys falls into the
170-190ksi range.
2. Consistency: Filament winding is the most consistent carbon tube manufacturing technique available. CNC fabrication offers the most uniform,
reproducible, and predictable method for manufac-
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Argen TC™ and Cirrus TC™ titanium and carbon fiber
Heat-treated cromoly tube sets include Columbus
Nemo™; Columbus Genius™; Reynolds 725™; True
Temper OX 3™; and Dedacciai Zero Tre™. These
tubesets are characterized by: high strength and
good workability (formability); a wider variety of tube
set options; and the ability to be brazed without
damaging the tubes. Their ultimate strength typically
falls between 150-175ksi.
The Argen TC™ tube set (used in the Elium Race and
Odonata) and Cirrus TC™ tube set (used in the Elium
SG) employs the same tube butting technologies as
does our Argen™ and Cirrus™ tube sets. However,
they feature carbon fiber tubes, which are used strategically instead of titanium in certain tubes within the
frame. As a result, for example, the Odonata's use of
carbon fiber seat tube and seat stays offers two
important benefits: weight savings of 10% over our
Axiom SG titanium frame, and improved damping
characteristics.
Standard 4130 representatives are Columbus Brain™;
Reynolds 525™; and True Temper OX 2™, among
others. This material has good formability, and is used
to create thicker, more stout tubes. Thus, optimally,
these tubes would be used when building a frame for
a larger rider. Ultimate strength generally is in the
120-150ksi range.
We designed the Elium (SG & Race) and Odonata's
titanium lugs to optimize joint strength and provide a
durable interface between the carbon and titanium.
The titanium tubes and lugs are machined to reduce
stress risers where the carbon and Ti meet.
Furthermore, the key to long life is the epoxy used, as
well as the bond area between tube and lug. The consistency of the bonding area between the carbon tube
and the titanium lug is critical for optimized bonding
strength. Since filament winding offers extremely tight
tolerances for all dimensions of the tube, including
tube diameter and wall thickness, we're able to maintain the proper adhesion necessary for improved
fatigue life and better joint durability.
Seven's Exclusive Tube Sets
Argen™ and Cirrus™ butted titanium
Seven's Argen™ butted and Cirrus™ Ultra-butted™
tube sets both start with the highest-quality, domestically sourced seamless 3Al-2.5V titanium tubing.
Though it comes with certificates from the mill, the
tubing's finish, straightness, and concentricity must
also pass our in-house inspection before we will use it
in a frame.
Seven has developed four proprietary tube butting
technologies, which, unlike some tube butting
processes, neither modify nor degrade the tube's
grain structure. This ensures that each tube has the
longest possible service life. And although it's not
easy, Seven maintains a wall thickness tolerance of +/0.001"—less than the thickness of a human hair. Once
we've butted the tubes, we subject them to another
round of inspection.
Origin™ butted steel
Seven works with the world's best tubing suppliers,
including Reynolds, Columbus, and True Temper, to
gain access to the widest selection of top quality steel
tubes available. In general, the goal of each individual
tubing manufacturer is to create tubes that are lightweight, reliable and exhibit superior mechanical characteristics. While all of our suppliers manufacture
excellent tubes, no single company makes a wide
enough variety of sizes to cover all of Seven's requirements. Thus, Seven's Origin™ steel tube set, from
which we fabricate all of our steel frames, draws from
the best, taking the performance of steel frames to a
new level.
Integrity 325™ straight-gauge titanium
Seven's Integrity 325™ tube set uses the same high
quality, domestically sourced 3Al-2.5V tubing as is
found in our Argen™ and Cirrus™ tube sets.
However, it does not go on to be butted before being
used in a frame. Therefore, the wall thickness and
diameter remain constant over the length of the tube.
For performance that lasts, the Origin™ tube set is
composed of proven, dependable, heat-treated cromoly steel and super-strength microalloyed steels such
as Thermacrom that have an Ultimate Strength of
140,000 to 200,000 psi and elongation of 8 to 15%.
Continued on page 10
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Seven Cycles
A Closer Look
Integrity 325™, Argen™, and Cirrus™: What
are the key differences in these tube sets? And
more important, how do they help achieve the
design and performance objectives set forth for
a particular frame model? Here we'll take a
closer look at Seven's exclusive titanium tube
sets and their integral relationship to our Alaris,
Axiom, and Alta frame models.
imum dent resistance and durability. On the flip
side, however, it does not allow for as finely
tuned ride characteristics, and results in a
frame that is heavier than one made from butted
tubing.
Argen
The result of 13 years of tube butting research
and development, our Argen tube set is a combination of single- and double-butted tubes
designed to create the optimal balance of
weight to performance. Though all Seven tube
sets allow for custom tube selection for each
individual rider's performance preferences,
Argen is the most tune-able, as it offers the
widest range of tube options and configurations.
From raw tubing to tube set
At Seven, we buy all of our titanium tubing milldirect in roughly 35 different straight-gauge
sizes, which are delivered to us in lengths averaging 15'. These tubes need to meet strict tolerances for fatigue strength, diameter, wall
thickness, finish quality, straightness, and concentricity. Whether destined for Ultra-butting™
or remaining straight-gauge, a tube's long journey toward becoming part of a Seven tube sets
begins here.
Cirrus
The Ultra-butting process we developed to create our Cirrus tubing is our most technically
sophisticated and yields our lightest tube set to
date. Using proprietary butting technology, we
shave weight wherever possible according to
the particular stresses that occur over the
length of the tube. With ultra light weight being
its primary objective, Cirrus is not recommended for riders over 200 lbs or those who demand
maximum frame stiffness.
Integrity 325
The tubing that goes into Seven's straightgauge Integrity 325 takes the most direct route
to becoming a tube set. Though each tube is
carefully selected according to the performance
needs and preferences of the individual rider,
our Integrity 325 requires the least amount of
processing and manipulation, and is consequently less expensive. It also possesses maxTubing
Feature
Advantage
Benefit
Consideration
Integrity 325
Straight-Gauge
Price; damage tolerance
Most affordable;
Heavier; less tune-able
most durable
characteristics
Light; best weight to
Most tune-able;
Best all-around;
performance; widest
optimized ride
no compromise
range of tube options
characteristics
Lightest; specifically
Great for climbers &
Not for everyone; narrow
engineered for
lighter riders; Light;
range of ride characteris-
light weight
compliant
tics; price
Argen
Cirrus
Double-Butted
Ultra-Butted
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SAME SIZE FRAMES.
DIFFERENT TUBE SETS.
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The expression “size-specific” tubing is often used to describe the benefits of one frame over another. Basically, it means that the tubing in,
say, a 17" mountain frame was selected to optimize the ride characteristics for the average person riding that size. It’s not a bad idea, but
here’s the problem:
Two people riding identical frames can be completely different
in weight and riding style. So if the tubing in these
frames was selected for the frame size and not for
the rider, at least one of the riders is going to be
compromising. This is why a lot of lighter riders find
their frames too harsh, while many heavier or more
powerful riders find theirs too flexible and even
break them.
Take Marilyn and Bernard, for example. They
ride almost exactly the same size frames, but
they’re very different riders.
marilyn
» MARILYN
8
Height:
5’ 8"
Weight:
128 lbs
Style:
Spins smaller gears
Preferences:
Long climbs
The frame:
17" Sola Ti
The ride:
Light & lively
CASE STUDY
Technical Supplement
Marilyn is known as a climber. She’s as agile as a cat and has a preference for spinning smaller gears. When we set out to build her frame, we
carefully selected each tube to create a very light, lively ride, while maintaining drive train stiffness. Now in its fourth season of hardcore racing,
Marilyn’s Sola has accompanied her to countless wins and titles, including World Championships in 1999 and 2000.
Bernard has almost 40 pounds on Marilyn. He loves technical single
track and will push a big gear to create short, powerful bursts. His additional weight and aggressive riding style demands greater stiffness from
his frame. By tailoring the diameter, wall thickness, and butt placement
of the tubes, we made Bernard’s Sola stiff and durable, without sacrificing comfort.
Same size frames, different tube sets. Seven goes beyond “sizespecific” tubing to bring you “rider-specific” tubing. Because no two riders are exactly alike.
bernard
» BERNARD
Height:
5’ 9"
Weight:
165 lbs
Style:
Pushes bigger gears
Preferences:
Technical singletrack
The frame:
17" Sola Ti
The ride:
Very stiff torsionally,
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but not harsh
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Technical Supplement
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Origin SC™ steel and carbon fiber
Each tube manufacturer has its own specialty and philosophy about how a tube set should be made.
Building on the strengths of all the manufacturers, an
Origin™ tube set consists of tubes selected specifically for a particular application and the unique cyclist.
For example, in one frame, Seven might pair an S3™
top tube with an 853™ down tube and seat tube, and
an exclusive Origin™ rear triangle. In another, Seven
might choose a UltraFoco™ top tube, EOM™ seat
tube, and an Versus™ down tube, with chain and seat
stays we've created specifically for that mix.
Inspired by our Argen TC™ tube set, our Origin SC™
tubing brings together steel and filament wound carbon fiber, which enables us to create a frame possessing the classic ride of steel, but with a lighter,
more comfortable feel.
Manufacturing
Overview
Although the Origin™ tube set is unique in and of
itself, its seat and chain stays are indeed its hallmark.
Designed purely for function, Origin's™ stays don't
require tapering. Before butting was invented, tapering
helped to soften a frame's ride. Today, tapering serves
little purpose in improving the ride of a high quality
frame because of the wide range of thin-walled tubes
and varying diameters that are achievable with modern
equipment. Indeed, Origin™ chain stays are stiffer for
a given weight than any tapered chain stay on the
market.
TUBE MANIPULATION
Tube Butting
A tube that is double butted, such as those found in
Seven's Argen™ tube set, has a thicker wall at its
ends and is thinner in its midsection. The joints of a
frame are its most highly stressed areas, and in a typical titanium or steel frame, possess lower mechanical
properties—i.e., strength—than the unheated portions
of the tubes. Thus, most failures occur at the frame's
joints. Butting efficiently strengthens the heat-affected
zone at the joints without adding significant weight.
Origin™ chain stays are the stiffest stays in the industry. They are the first—and only—chain stays to fully
leverage an oversized, untapered design that offers an
unmatched stiffness to weight ratio. Their oversized
nature requires that they have accentuated curves,
which allow for superior tire, chain ring, crank, and
heel clearance.
Seven's ultra-butted Cirrus™ tube set takes butting to
a whole new level. It's similar to a double-butted tube
in that the wall thickness at the ends of the tube is
greater; however, the wall thickness will vary extensively over the tube length according to the complex
stresses the tube will undergo at various points.
Seven's Cirrus™ tube set makes possible the lightest
bikes available.
Similarly, the tube set's seat stays—the lightest available—have undergone an evolution to become the
refined functional tubes that they are today. Origin™
seat stays boast maximal vertical compliance without
sacrificing torsional rigidity. As a result, the bike's ride
characteristics—including traction and tracking—are
much improved as the rear wheel maintains contact
with the ground over rough terrain, through tight corners, and during acceleration.
Tube Butting Processes
Traditionally, tubing has been butted internally. Using
an internal mandrel, material is displaced from the
center of the tube to make the tube thinner in that
area. The mandrel must then be drawn out of the
tube, past the thick sections, so the tube must be limited in its thickness differentials. Internally butted tubing has some advantages, such as its usefulness in
lugged construction. However, internally butted tubes
typically are limited to a 40 percent thickness differential to allow the mandrel to be removed. Therefore,
More important than any other aspect of an Origin™
tube set is the fact that it is a "tailored" tube set. The
tube options, sizes, and wall combinations are virtually
limitless, ensuring that it will always meet the demands
of the rider. The Origin™ tube set provides advantages
that no other tube set, nor frame manufacturer, offers
today.
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Technical Supplement
there are fewer tube sizes from which to choose, and
the variation in thickness may not be ideal. Externally
butted tubes suffer from no such differential limitations.
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Vertical
In addition, the properties of an internally butted titanium tube are affected by the excessive manipulation
that occurs when using a mandrel. Although cold
working can increase strength, too much cold working
after the tube mill's final annealing and stress relieving
cycles can detrimentally change the texture of the tubing. The tubing's CSR (Contractile Strain Ratio)
increases—beyond its optimal rate—resulting in poor
fatigue characteristics.
Lateral
1.75:1 Ratio
Round and oval tubes,
Round tube
RELATIVE STIFFNESS COMPARISON
Oval tube
Torsion
External butting is a superior method for tube reinforcement, and, generally speaking, produces a lighter
tube with equal strength, or a stronger tube with
lighter weight, than an internally butted one. There are
two key advantages to externally butted titanium tubing—one metallurgical, the other, mechanical.
Bending,
Lateral Plane
Bending,
Vertical Plane
0.0
0.5
1.0
1.5
Tubes compared are of equal weight and optimized dimensions
Metallurgically, drawing titanium tubing at the mill
determines its crystallographic texture, or grain orientation. And grain orientation affects yield strength, ductility, and fatigue strength. The mill controls the grain
texture with a lengthy process of rocking and heat
treatments. The control of these steps creates an optimized fatigue life and ductility. The tube leaves the mill
with the best possible combination of properties.
Therefore, when titanium tubing is cold worked by
tapering or internal butting—whether by the mill or by
secondary vendors—the tube's properties will be
compromised.
Shaped Tubing
Odd tube shapes (ovals, so-called geometrically
enhanced tubes, squares, six-sided tubes, etc.) are
becoming more and more common these days. At
first glance, these shapes appear to enhance the performance of the bike. Unfortunately, in most cases,
performance is actually compromised.
Stiffness: A round tube is the optimal shape to
achieve a balance of all bending and torsional
stresses a bike undergoes. Odd shaped tubes
always compromise torsional stiffness, and bending
stiffness is always compromised in at least one
plane. Overall, round tubes are stiffer for a given
weight. Although oval tubes may be stiffer in the
major plane, they are more flexible in the minor
axis. In addition, oval tubes suffer most from a lack
of torsional stiffness.
Mechanically, in pure engineering terms, an externally
butted tube is a more efficient use of material. For a
given tube's weight, an externally butted tube will be
stiffer; for a given stiffness, the tube will be lighter. In
addition, internal butting can hide scratches or notching due to mandrel movement. Surface scratches create stress risers that can lead to premature failure.
Externally butted titanium avoids these problems.
Grain Structure (titanium only): Grain structure is
what provides the strength and toughness of a
material. The mill draws the tube in a specific way
so that the resulting grain structure is optimized for
strength and fatigue endurance. Thus, if the shape
of the tube is changed, the tube's grain structure is
also changed. As a result, the tubes' strength and
durability are compromised.
Using proprietary processes that do not affect the tubing's grain structure or internal surface, Seven creates
externally butted titanium tubing that maintains its
fatigue strength and ductility. These processes allow
for every possible permutation of tube diameter and
wall thickness, in addition to an optimum strength-toweight ratio, and create no surface defects or scratches.
Continued on page 13
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Technical Supplement
Seven Cycles
Evaluation of Shaped Tube Strengths & Weaknesses
Shape
Example
Performance
Strength
Performance
Weakness
Shapes that effect the
mechanical properties
of the tube: stiffness,
compliance, etc.
Tapered or multisided tubes
Aesthetics (subjective)
Marketing differentiation
A constant diameter, butted tube
will be lighter for a specified
stiffness
Shapes that facilitate
the use of common
and popular
components
Seven's S-bend
chain stays
This allows for the use of
a large diameter, stiffer
tube and reasonable tire
and chain ring clearance
Too much shaping reduces
performance
Shapes that enhance
aerodynamics
Seven's Teardrop
shaped down tube
option
Optimized aerodynamics
and enhanced speed
Reduced overall stiffness; see
above. However, this is not a
'weakness' if the primary goal of the
bike is aerodynamic optimization.
Seven's Aero Down Tube Option At-A-Glance
FEATURE
ADVANTAGE
BENEFIT
Teardrop shape
Most aerodynamic shape; teardrop slices
through wind
Easier to handle in cross-winds;
faster in head-wind
Elliptical leading
edge
Cuts through wind with lower turbulence
than circular leading edge
Higher speed for a given sustained,
power output
Laminar flow extends closer to trailing
edge than circular leading edge designs
Minimized turbulent surface area
resulting in higher speed for a given,
sustained, power output
Aero trailing
edge
Wake behind trailing edge of the tube is
reduced
Less drag and cleaner air flow behind
down tube equals higher speed for a
given, sustained, power output
3:1 cross section is
optimized for the
angle at which the
down tube is
exposed to the air
Design takes into account that the down
tube slices through the air at an average
angle of 47 degrees
The design is based on real-world
usage
The tube's width (minor axis) provides
excellent lateral rigidity; the height of the
tube (major axis) is required to maintain
the ideal 3:1 cross section
Taller tube height provides superior lateral The bike will accelerate and climb
rigidity
better than other aero tube bikes
Down tube only
Seat tube - dirty airflow from legs
pedaling
Seat stays - dirty airflow behind legs
12
Aerodynamics without ride quality
degradation
Technical Supplement
Seven Cycles
Shot Peening
Notch Sensitivity (titanium only): Most shaped
tubes are formed by a mandrel. However, a mandrel causes internal scoring. Internal score marks
are stress risers that can potentially lead to failure.
So while round tubes may not be the latest fashion, they are reliable, durable, and result in bikes
with optimize weight to performance that last for
the long haul.
Shot peening is a process of firing thousands of small
spherical "shot" at a surface. It literally peens the surface of the material, reworking it to put it under compressive stress.
In theory, the failure point for most structures that
undergo fatigue cycling, such as a bicycle frame, is its
outermost surface. The natural tension of the surface
can lead to crack induced failure. Correctly applied,
shot peening creates localized compression of the
tubing surface, thereby reducing the likelihood of crack
initiation.
To be clear, there are occasions when a shaped tube
is useful. However, its important to look at the underlying purpose of a shaped tube, since some aspect of
performance is almost always compromised as a
result using a non-round tube. The information below
provides strengths and weaknesses for the three main
categories of shaped tubes.
However, it is extremely difficult to properly shot peen
an intricate, welded, small diameter tubular structure,
such as a bike frame. The difficulty arises from the
trajectory of the shot. To be effective as a means of
increasing fatigue life, the shot's trajectory is best
applied at approximately a 90-degree angle to the
material's surface. Unfortunately, a frame's tube diameter is small enough that much of the shot is hitting
the surface at 60 degrees or even less. At this angle,
the shot is skimming the surface, instead of peening it.
This skimming does not benefit the surface structure.
SURFACE
TREATMENTS
(titanium only)
Anodizing
A small number of manufactures offer anodizing as a
way of decorating the surface of titanium frames (or
components). Basically, the process creates a dense,
colorful film of titanium oxide, which adheres to the
frame's surface. Ironically, this is the same type of
oxidation that any skilled titanium welder will prevent at
all costs, because it will cause the weld joint to
become extremely brittle. (This is why Seven's expert
welders bathe both the inside and outside of a titanium frame's weld joints in an inert gas, thereby protecting the molten metal from the high levels of nitrogen
and oxygen that naturally occur in the environment.)
The main drawback to shot peening as a titanium surface treatment is in the durability and maintenance of
the finish. If it becomes scratched or worn-looking—
as is likely from normal use—it can't easily be
restored. By contrast, the satin finish applied to Seven
titanium frames can be maintained simply with the use
of a little ScotchBrite™ (Very fine AA) and a light application of a wax-based furniture polish.
The titanium oxide film created by anodizing is, thus,
extremely brittle, so the frame's surface cannot flex as
it would during normal use. Cracks form through the
anodized shell, which will eventually propagate into the
tube wall, ultimately causing frame failure.
Seven strongly advises against anodizing titanium.
Hence, we will void the lifetime warranty on any Seven
frame that has been anodized.
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Technical Supplement
Seven Cycles
Polishing
The highly polished finish offered on some frames is
created using an abrasive process that smoothes the
surface by removing material. It's difficult to control
the amount of material that is removed—particularly
around the frame's joints. This material reduction will
make the joints weaker, which could lead to frame failure.
A polished finish is also more difficult to care for longterm than a satin finish. A small scratch on a satin finish can easily be removed using Scotchbrite™, so its
elegance is easy to maintain for the life of the frame.
WELDING
TECHNIQUES
Titanium
Since even fingerprint oils (hydrocarbons) will dramatically degrade a weld joint's fatigue life, we prepare
and clean each tube prior to welding. Our machinists
wear cotton gloves during the welding preparation
stages, even before any welding is performed, and
welders also wear cotton gloves while welding and
handling any frame to keep the tubes from becoming
contaminated.
Proper welding technique is one of the most important
steps in the construction of a titanium frame, since
titanium has a tendency to alloy with anything it touches. Fortunately, this is only a problem when it is in its
molten state during the welding process (over 1700
degrees C).
Oxygen, nitrogen, and hydrocarbons are the three
most damaging elements to a molten titanium weld
bead. If any of these substances enters and mixes
with a titanium weld bead, the fatigue life and structural integrity of the joint is greatly compromised.
To keep airborne contaminants out of the weld area
during welding, we bathe both the inside and outside
of the frame's joints in a completely inert gas, thereby
protecting the molten metal from the high levels of
nitrogen and oxygen that naturally occur in the environment. A positive pressure purge system creates a
purely inert atmosphere inside the frame. Outside, the
modified TIG torch produces a bath of inert gas to
shield the bead from possible contamination. The inert
gas maintains the titanium's purity, and does not react
with the metal.
Therefore, Seven Cycles uses a proprietary TIG welding process to build our titanium frames. Specially
modified TIG welding torches, lenses, and cups
ensure that the welded joint has the highest possible
level of strength and purity. We have also specially
modified our welding machines to optimize weld
strength in all of our frames.
Individuals who weld titanium must have very steady
hands to avoid both flaws and contamination in the
weld zone. Even something as simple as inappropriate
weld wire movement can actually create vortices that
stir up nitrogen and oxygen and allow them into the
molten TIG bead, thereby compromising the joint's
strength.
Welding Systems
Alignment
accuracy
HAZ minization
Strength
Seven
Multipass
Single
Pass
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Technical Supplement
To minimize heat distortion and optimize bead penetration, Seven uses various weld wire sizes and bead
sizes, depending on the joint and tube selection. Heat
distortion must be minimized because it can create
problems with frame alignment that affect the bike's
handling and tracking during riding. Nonetheless, we
still perform five frame alignment checks throughout
the welding process to maintain precise alignment. If a
slight alignment adjustment is necessary, the welding
steps can be modified to bring the frame back into
alignment.
Seven Cycles
much more expensive than brass, which is typically
used, it requires less heat. Therefore, the strength of
the base metal is maintained. Silver also flows better
than brass, so the likelihood of voids in the brazed
area is reduced, thereby maximizing joint strength.
FRAMEBUILDING
AT SEVEN
Our approach to framebuilding is thorough, comprehensive, and unique. From the inception of a frame's
design to its shipment out the door, all eyes are on the
details.
Steel
To work with Origin™ tube sets, Seven's welders must
successfully pass an in-house certification process
that typically takes more than four months to complete. Steel frames are also protected from contamination by using the same positive pressure purge system used on our titanium frames. Dispersing atmosphere while welding steel frames is not necessary;
however, removing potential contaminates allows for
the strongest welds possible.
Creating the Blueprint
When we receive an order for a custom frame, we first
thoroughly review it. Our Custom Kit™ is designed to
provide us with a complete rider profile, and tells us
your:
Body Measurements
Current bike measurements
While there are several methods of joining steel frame
tubing, all of Seven's Origin™ tube sets are assembled using a TIG welding technique that is tailored
specifically to Seven's requirements. Seven prefers a
TIG welded joint over the more common lugged
design for two primary reasons:
Riding habits
Riding preferences
We look for any missing data or discrepancies, and if
we have questions, we call the dealer for the additional information. From there, we develop preliminary
frame specifications using our proven Seven Fit
Methodology (SFM™) and a custom CAD program.
We then contact you (at a prearranged time of your
convenience) to conduct our client interview, which
allows us to clarify any additional information and provides you with an opportunity to ask questions about
the design of your Seven.
1. Fine-tuning of the frame's ride characteristics can
be tailored to a greater degree without the tube
diameter size limits imposed by lugged construction.
2. A frame can be customized without geometry constraints. Lugs are available in limited sizes, or must
be modified to accommodate even slight variations
from typical geometry.
After the client interview, we finalize your specifications
and fax a Specification Confirmation form to your dealer for review. Once you and your dealer review the
specs, simulate our fit recommendation, and confirm
the order, we put your frame into our production system. We then choose your frame's tube set to create
optimal ride characteristics. With your tube set selected, we create a CAD drawing (or blueprint) of your
frame, which is now ready for machining.
TIG welding also creates the lightest joints possible,
and, with the use of special weld wire, produces joints
that are very ductile and extremely strong. The result is
excellent service life for our steel frames.
For enhanced strength, Seven silver-brazes all of the
small parts—cable stops, shifter guides, water bottle
bosses—on our steel frames. Silver brazing is the
strongest type of brazing possible. Although silver is
15
Technical Supplement
Machining
Seven Cycles
designed tooling. After the chain stays are bent and
coped, they are then ovalized at the "tire point" to
allow for maximum tire clearance.
The CAD drawing stipulates the frame's geometry—all
angles, tube lengths, and tolerances—as well as the
tubes' wall thicknesses, diameters, butt thicknesses,
and butt lengths, all of which are developed specifically for each individual cyclist.
Next, our machinists stamp the inside of your frame's
dropout on the drive (right) side with a serial number
for identification. After the dropouts are coped and finished, our machinists drill your frame's water bottles
holes and any necessary breather holes for proper
weld integrity. The last step before tacking is a complete frame tolerance check.
The machinists' first step is to review the CAD drawing
and gather the equipment necessary to meet the
frame's special needs. Since every frame is custom
made, every tube set differs, and so do its machining
requirements. Machine cutters, feeds, speeds, and
even cutting oils must be ready and in place before
they can begin to build.
Tacking
Tacking is the manufacturing step that immediately
precedes frame welding. During tacking, a small spot
weld, called a tack, is applied strategically to each of
the frame's joints to hold the tubes together temporarily to prepare the frame for welding.
Next, they collect the tubing and visually and mechanically inspect each tube to be sure that it meets the
frame's required spec. Our machinists then cut the
tubes to length based on the CAD drawing. The
frame's head tube is also cut to length and externally,
eccentrically butted to size using Seven's custom tooling.
Although our machinists have already placed the tube
set in our custom-made frame jig for a tolerance
check, they remove the tubes from the jig before tacking. When the tacker receives your tube set, s/he
degreases the inside and outside of each tube to
remove any oil, cutting fluids, or dirt, and then wire
brushes each tube's weld area to remove any oxidation or degreasing residue. From this point on, anyone
who touches the tubes must wear clean cotton gloves
to prevent finger oils from contaminating the tubes.
Even a small amount of oil on the weld—such as that
left behind by a fingerprint—can degrade the weld and
cause premature failure at that joint.
After cut-off, our machining team carefully copes the
ends of the tubes so that they'll fit together precisely,
resulting in proper frame geometry and tolerances.
While the front triangle of the frame is being coped
and prepped for welding, the rear triangle is undergoing a similar process. The rear triangle receives some
additional special treatment at this stage: our craftspeople create the sinuous bends in the frame's seat
and chain stays using a hydraulic press and custom-
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Technical Supplement
Since tacking is essentially part of the welding
process, a welder who specializes in tacking does the
job. The tacker carefully positions the tube set in our
custom-built jig. The jig is designed to be flexible to
accommodate custom frame needs, as well as to hold
very tight tolerances and maintain alignment of the
tubes during tacking.
Seven Cycles
In addition, weld consistency is a sign that the welder
is paying attention: a consistent, pretty bead shows
that the welder is focused and interested in quality.
And an even weld doesn't allow us to conceal flaws.
The frame's joints are welded in a precise, staggered
pattern so that the frame maintains its alignment. The
purpose of this meticulous system is to eliminate misalignment or the need for cold setting; it guarantees
the straightest TIG-welded frame.
While we tack the frame, the jig holds the tubes
together in their proper orientation and with the correct
angles. The jig also accommodates an atmosphere
purging system that creates a positive pressure, or
flow, of argon gas during tacking. This inert gas keeps
the weld zone free from contaminants such as oxygen,
nitrogen, and hydrogen, and therefore, assures optimal
welded joint strength.
Because a straight frame is so important, we check
each frame's alignment a minimum of five times during
welding to ensure that it falls within our specifications.
Should a frame show any signs of misalignment during
the welding process, we alter the weld sequence
process to pull the frame back into perfect alignment.
During tacking, every frame is subjected to eleven
alignment checks to guarantee the straightest, most
accurate frame possible. No frame leaves the tacking
phase without passing every one of these inspections.
Our tacking methodology is time-consuming but it is
the best way to ensure that we create the cleanest,
strongest, straightest frame.
Once the frame has been welded and its alignment
meets our strict tolerance standards, it's ready to have
brake bosses, cable guides, rack mounts, and other
parts welded on. These parts are tacked then welded
to the frame using a method similar to that used to
tack the frame. Custom-made fixtures created by
Seven hold the parts in place to ensure proper placement and alignment. We are then able, taking proper
frame purging precautions, to weld the parts onto the
frame.
To prevent re-oxidization or dust accumulation that
can cause inferior welds, the tacked frame is not
allowed to sit. Our methodical custom frame manufacturing process assures that as soon as the frame is
tacked, the weld process begins.
Final Machining
Final machining is the first step in frame finishing. This
step includes threading and facing the bottom bracket
shell, an extensive alignment check, facing the head
tube, and installing a filament-wound composite seat
tube insert. These crucial steps help ensure the bike
rides straight and takes less effort to keep it going in a
straight line. It also helps make the bike safer to ride
and more sure-footed and fun when descending and
cornering.
Welding
Welding is by far the most time-consuming part of the
frame building process. It takes so long, in part,
because cotton gloves, weld benches, and fixtures
must all be immaculate. Our purge process is elaborate and deliberate. We complete several alignment
checks. Welders adhere to a strict welding sequence,
and our focus is on the quality of the bead—not the
speed.
We start the final machining process by placing a
freshly welded frame in a CNC (Computer Numeric
Controlled) milling machine, which we have custom
tooled and fixtured specifically for the purposes of precision threading and facing the bottom bracket shell.
Cutting the threads post-welding ensures the greatest
possible precision, since the intense heat used in
welding can create tube distortion, and thus distort the
threads of the pre-threaded bottom bracket shells
We weld the frame's joints maintaining an even flow of
argon throughout the frame. Seven's welds are legendary for their beautiful, uniform look. Bead consistency—size, shape, metal content, and overall flow—is
striking, and also serves an important mechanical purpose. A neat, even bead prevents a stress riser from
appearing in the weld zone.
17
Technical Supplement
Seven Cycles
design also allows the use of any type of seat post
without the need for grease.
commonly used by other frame builders. Facing
means that we re-plane the ends of the tube so that
they are perfectly flat and parallel to each other, ensuring in this case that the bottom bracket will function
properly and fit precisely. This has an important effect
on rider biomechanics, since the rider's knees stay in
plane with the frame if the crank arms are in plane to
the frame.
Rather than press in the sleeve, we use an aerospace
grade epoxy to secure it in place, since pressing can
distort the sleeve. With the epoxy method, the seat
post slips in smoothly. Once the sleeve is inserted, we
use a custom oven to dry the epoxy for maximum
strength. The oven—custom engineered and built by
Seven—also allows us to cure up to six carbon frames
at a time. At 175 degrees, dry time is reduced from
twenty-four hours to a mere twenty-five minutes. This
time savings allows for Eliums and Odonatas to be finished in the same production day.
The CNC mill utilizes a water-based lubricant while
cutting the bottom bracket threads and facing the
sides. Although oil-based lubricants provide greater
service life of the cutting tools, the water-based lubricant is more environmentally friendly, as well as safer
for those who operate the CNC machine.
The last step in final machining is to degrease the
entire frame. From there, it goes on to finishing.
The efficiency and precision of the CNC machine allow
us to hold the bottom bracket shell width and facing
to a tolerance of 0.0015" (1 ½ thousandths of an
inch). This ensures the longest possible service life of
the bottom bracket bearings, lowers drag on the
cranks, and provides the most accurate starting point
for all other alignment checks.
FINISHING
Titanium Frames
A titanium frame spends almost a day in final finishing.
Cleaning the entire frame to remove any oil or residue left
over from final machining is the first order of business.
Next, we brush the frame with a nylon wheel to bring the
raw titanium to its glossy, natural luster. Seven's titanium
frames are not polished, so no material is removed from
the tubes' surface. Because we use only the highest
quality tubing to build our frames, the tubes have no surface scratches or imperfections that would make it necessary to polish, paint, bead blast, or otherwise alter the
frame.
Once the bottom bracket shell has been threaded and
faced, we ensure that it, as well as the head tube,
seat tube, and rear triangle are all properly aligned to
each other. The next step in the alignment exam is a
wheel check designed to ensure that the rear wheel is
in plane with the seat tube and head tube. If a bicycle's wheel is out of plane, the bike will constantly try
to turn, forcing the rider to adjust his or her body and
positioning to compensate for the misalignment.
We proceed by using an H-tool to check that the
dropouts are in plane with one another. We also
inspect the alignment of the derailleur hanger to
ensure the shifting will be spot-on.
To enhance the frame's finish, we simply touch it up with
Scotch Brite™, a 3M product that might remind you
of—but isn't—the pot scrubber in your kitchen sink.
Grade A, or very fine, gives us the best results. Once the
frame has been wheeled and buffed, it's ready for
decals, which are specially designed to adhere to titanium. As a final touch, we spray the entire frame, head
tube to dropout, with a generous application of light
wax; this helps to keep fingerprint oils, chain lube, and
other greasy substances from leaving marks on the
frame.
Once the alignment inspection is complete, we ream
and face the frame's head tube and seat tube.
Reaming the seat tube prepares it to accept our
exclusive filament-wound composite sleeves.
Because the diameter of the seat tube is too large to
accept a standard size seat post, we use our precision-sized insert to accommodate a 27.2mm seat
post. In addition to being half the weight of an aluminum sleeve, our composite insert also guarantees
that the seat post won't gall or seize. The "no-creak"
Then, we install the remaining bits of hardware, including
water bottle mounts, a laser-cut stainless steel head
badge, and a seat top. The finishing touch is a laminat-
18
Technical Supplement
ed, wallet-size frame card that we affix to the frame. It
lists the frame's geometry and serial number, and is
signed by all the individuals who built it to signify that the
frame is indeed one of a kind.
Seven Cycles
ground up, it comes in rakes ranging for
32mm to 56mm—more than any other
fork—to ensure optimum handling. The 5E
features a fully integrated crown, legs, and
1 1/8" steerer and weighs 440g at
285mm. What's more, it's the only highperformance road fork available with
optional fender mounts and clearance
for a 32c tire.
Steel Frames
Before receiving its first coat of paint, a Seven steel
frame is meticulously prepared. To ensure the best
paint finish possible, our finishers carefully clean
brazed and welded areas and bead-blast the frame's
entire surface.
See page 21 for details on the
Seven 5E Carbon Fork
Paint is applied using a careful, deliberate approach
that results in superior coverage. The painter primes,
bakes, and then wet sands the frame before painting.
Next, several layers of base coat are painstakingly
applied, decals are affixed, and finally, multiple layers
of high solid clear coat are baked on for a lustrous finish.
STEMS
The stem is an integral part in
creating the overall fit and handling of
your bicycle. The frame and stem combination, properly designed and sized, allows for optimal front-end
height, reach, ride characteristics, and handling.
SEVEN CUSTOM TI STEM
Once the frame has been painted, we apply rust
inhibitor to the inside of its tubes. Our finishers then
affix the head tube badge and seat top, and inspect
the frame one last time to be sure it's in top-notch
condition. Steel frames, too, receive a wallet-size
frame card listing the frame's geometry and serial
number, signed by all the individuals who built your
frame.
Our custom Ti stems feature a 4-bolt removable faceplate. The stems are available in any length, any rise,
and two stiffness options: S2 Standard, and S3 SuperStiff.
The ride of the S2 is very similar to that of a forged
Seven Component
Technology
A properly designed and fitted bicycle frame provides
the foundation for performance and comfort. That is
only part of the equation, however. Just as important
is the cyclist's selection of components. Seven offers
the four components that are most influential on the
fit, ride quality and handling of your bicycle. Those
components are: the fork, stem, handlebar and seat
post.
aluminum stem, but with better dampening characteristics. It is suitable for most riders. Estimated weight
for a 120mm is 159 g.
SEVEN'S 5E CARBON FORK
Riders over 200 lbs will benefit most from the S3. It is
also appropriate when frame geometry dictates a long
stem (over 140mm). An S3 stem weighs approximately 167 g.
Seven's 5E is unique among high-performance forks.
In addition to the best lateral stiffness-to-weight ratio
of any molded carbon fork, the 5E affords tremendous
practicality. Designed by Seven completely from the
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Technical Supplement
Seven Cycles
Seven's stems interface with the fork using a double
pinch bolt, which provides maximum durability and,
unlike an internal binder, won't damage a carbon fork
steerer. In road or mountain styles, the stems are constructed from domestically sourced seamless Ti 3-2.5
tubing, and use CNC machined Ti 6-4 binders. Seven
titanium stems are backed by a lifetime warranty.
ROAD HANDLEBARS
See page 22 for details on the Seven Custom Ti Stem
See sevencycles.com for handlebar specifications
Seven’s high-performance butted 7050-T6 aluminum
road handlebar weighs just 219g. The 50mm radius
bends on the drops make brake lever and ergo position more comfortable and provides more hand space.
The bar is available in 44cm, 42cm, and 40cm widths
with 31.8mm diameter and 135mm drop.
SEVEN ALUMINUM STEM
Our high-strength 7075-T6 aluminum stems feature a
4-bolt removable faceplate with a reverse bolt design
for increased service life. Just 131g for a 11.0cm,
these lightweight stems are available for road or
mountain . Choosing the Ti bolt upgrade lightens stem
to an incredible 116g.
MOUNTAIN HANDLEBARS
Seven offers two mountain handlebars. Our Ti flat bar
is built to order, according to your specifications for
length, bend, and stiffness. Strong, yet forgiving, it
weighs 158g. Or choose our 20mm aluminum riser
bar, weighing just 218g at 26".
See page 22 for details on the Seven Aluminum Stem
See sevencycles.com for handlebar specifications
ROAD SEAT POST
Our cold-forged aluminum
7075-T6 posts feature nearly infinite adjustability for
perfect saddle rotation. Low
profile, lateral 2-bolt clamp
design holds saddle rails
securely and is easy to
adjust. These super-light
27.2mm post s are offered
in 280mm (204g) or 400mm
(256g).
See sevencycles.com for
seat post specifications
20
Technical Supplement
Seven Cycles
Product Data Sheet for the Seven 5E Carbon Fork
Feature
First carbon fiber fork
designed from the ground
up by a custom bike
manufacturer
Advantage
Benefit
A long list of exclusive features (see
below
The fork is able to provide contradicting benefits of aerodynamics and handling precision, performance and comfort
Developed by bike designers; fork is
designed to match frame characteristics rather than designing frames to
match pre-existing fork options
Perfect match of fork to frame and
rider for best handling and performance.
First carbon fiber fork
designed to allow for
nearly infinite rake choices
Fork is optimized to the frame, rather
than vice versa. Allows fork handling
to be integrated into the frame design.
This fork sets a new standard for custom frame/fork tuning. Handling can
now be perfectly optimized to each
rider's needs.
18 different rakes available
•
Optimized trail on every bike we
build.
•
Eliminates the need to compromise frame geometry based on
rake constraints.
Precise control over bicycle handling
characteristics. Can deliver exactly
what the customer is looking for.
Proprietary one-piece
manufacturing process
Fully integrated carbon steerer, crown
and leg construction features 100 percent carbon throughout
Unrivaled strength, very lightweight
Wide fork crown
Highest lateral rigidity of any popular
carbon molded fork, without added
weight
Precise handling
•
More tire clearance
•
Fits tire size up to 28c w/fender
•
No modification to the fender
•
Fits tire size up to 32c w/o fender
necessary
•
Reduces build time; easier setup
•
The best cornering and descending performance molded carbon
fork available
•
More sure-footed, so you can
attack the descents
Widest blade of any molded fork available
More lateral rigidity than any other
popular carbon molded fork, without
added weight
47 mm deep blades, true
aerodynamic shape
Excellent aerodynamics while enhancing lateral rigidity
Faster than any other performance
fork on the market
Optional integrated
fender mount
Fork specifically fabricated for your
needs
Fork looks great:
•
Fender mounts for fenders
•
No mount if you don't want fenders
Painted finish
No cosmetic layer of carbon fiber
Lighter; all performance, no filler
Custom designed top cap
Evenly distributes stresses on steerer
Prevents steerer damage
21
Technical Supplement
Seven Cycles
Product Data Sheet for the Seven Custom Ti Stem
Feature
Advantage
Benefit
Full custom construction
Available in any length, any angle, and
two different stiffness options
Perfect fit and rider-specific ride
characteristics
3Al-2.5V titanium
Precisely machined, welded, and
finished in the same manner as our
frames
Longest service life
Two stiffness options
Custom tuned stem extension allows
Seven to tune the flex characteristics
Provides customers with the road feel
they are looking for
Reversed, 4-bolt faceplate
Prevents the bar clamp bolt heads
from working against the faceplate
Reduces risk of premature fatigue
failure, cleaner looking
Seven custom faceplate
Better clamping surface area;
designed by Seven
Less flex, maximum strength
Stainless steel bolts
Greater strength; will not rust
Cleaner looking
Integrated washers for
faceplate bolts
No parts to lose
Easier, faster setup and changeover
Product Data Sheet for the Seven Aluminum Stem
Feature
Advantage
Benefit
3-dimensional forging
Better grain flow, 1 piece design
Higher strength, longer service life,
lightest weight
Reversed, 4-bolt faceplate
Prevents the bar clamp bolt heads
from working against the faceplate
Reduces risk of premature fatigue
failure, cleaner looking
Bias cut steerer clamp,
opposing clamp bolts
Avoids point loading on carbon steerer
Reduces risk of carbon steerer failure
7075-T6 aluminum body
Strongest aluminum alloy available
Higher strength allows lightest weight
Seven custom faceplate
Better clamping surface area;
designed by Seven
Less flex, maximum strength
Stainless steel bolts
Great strength, will not rust
Cleaner looking
Optional titanium bolts
Lighter than stainless bolts
15 gram weight savings
Integrated washers
No parts to lose
Easier, faster setup and changeover
22
Technical Supplement
Conclusion
There are several good materials available today that
are suitable for bicycle frames. Depending upon the
frame's usage and your budget, what's best for you
may vary from that of other riders. The most important
variables to keep in mind when selecting the best
bicycle are: overall bike fit, the builder's (and bike
retailer's) reputation, frame material, and components.
Framebuilding today is just as much a science as it is
an art. The use of the proper materials, processes,
and designs are equally critical to a manufacturer's
success. Seven continues to explore alternative materials and manufacturing methods in our ongoing quest
to fabricate only the highest quality products.
Seven Cycles, Inc. 125 Walnut Street
Watertown, Massachusetts 02472
Copyright (c) 1998-2005 All rights reserved. May not be reprinted
without express written permission from Seven Cycles. Version 6.1
23
Seven Cycles
Technical Supplement
Notes:
24
Seven Cycles