Easton EC90 Aero 55

easton b Bikes
Easton EC90
Aero 55
Are these the carbon
aero hoops to do it all,
or is Easton dreaming?
Words James Spender
I
first rode these wheels at their launch
back in June 2013 and they made such an
impression that I was eager to get hold of
a pair for a full Cyclist test. It was a long wait.
Full-blown production and shipping started earlier this
year, and they’re only just starting to arrive in the UK.
That first ride on the Aero 55s was in the Dolomites,
spanning a day that provided scorching sun at the foot
of the mountains and blizzarding snow at the top. There
were teeth-grinding climbs and hair-raising descents,
drawn out drags and even a crash (not me, and not
anyone’s fault), but I came away thinking the Aero 55s
handled themselves immaculately, and they weren’t even
firing on all cylinders. That’s because, while the end goal
of the clincher design was to be run tubeless, the units
I trialled then were tubulars. Now these Aero 55s are the
full tubeless deal. The extra material for the specially
hooked tubeless rim adds 253g to the wheelset compared
to the tubulars, but I’d readily make that compromise
because fitted with 25mm Schwalbe Pro One tubeless
tyres, the Aero 55s rode beautifully.
Quite often 50mm-plus deep-section wheels grumble
and reverberate along on uneven road surfaces thanks to
their massive rims and short high-tension spokes. Not so
the Aero 55s. Even on rough ground the sensation is that
the bike is gliding over the crests of miniature peaks. P
The details
Weight
1,583g pair (702g front,
881g rear)
Rim depth
55mm
Rim width
28mm (external),
19mm (internal)
Spoke count
16 front, 20 rear
Price
£2,400
Contact
silverfish-uk.com
cyclist
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Bikes b easton
aerodynamics
Easton has gone to great
lengths to analyse the drag
of the Aero 55s at a wide
range of yaw angles. The
result is a wheel that can
handle crosswinds and feels
extremely quick on the road
For such deep wheels they
pick up well, but their real
talent is for holding speed.
No wheels have felt faster
P Easton has spent a lot of time in the wind-tunnel, in
the lab and on designing natty little diagrams and tables
to display just how much faster the Aero 55s are than
anything on the planet.
The problem with making aero data comparisons is the
huge number of variables at play. The bike, tyres, rider,
speed, wind direction (yaw) and even what wind-tunnel
is used can all affect the results, meaning manufacturers
often cherry-pick conditions in which their wheels
come out on top, which may not reflect the real world, nor
make comparisons with other wheels fair. What makes
Easton’s results interesting is the considerable work it
has put into levelling the playing field, testing multiple
configurations in the San Diego Low Speed Wind Tunnel
to better replicate the drag on a bike. That data has then
been assimilated by Easton into ‘Wind Average Drag’
(WAD), essentially a value based on an average of various
degrees of yaw – a method that was pioneered in the
automotive industry in the 1970s.
The argument goes like this: tests on Wheel A show it
has the least drag, ie is the ‘fastest’, at 7° yaw, while tests
on Wheel B show it’s the fastest at 15° of yaw. So which
wheel is actually fastest overall, bearing in mind that on
real-world rides you can’t guarantee a consistent wind
direction? By testing both wheels across a range of yaw
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cyclist
angles and applying WAD, Easton arrives at an average
value that can be legitimately compared. Using this data,
according to Easton, the Aero 55s trump all-comers,
including comparable Enve, Hed and Zipp wheels.
Easton says the Aero 55s will save 32 seconds (tubular)
and 29 seconds (clincher) over 40km at a bike speed of
48kmh compared to its nearest competitor (Enve’s 3.7s
are next in line at 20 seconds). Easton points out that
48kmh might not be every average bike rider’s speed, but
that it has become the benchmark figure in the industry,
hence Easton has adopted it too. How all these wheels
compare to one another at lower speeds is not certain,
but I’d say the Aero 55s would fare extremely well.
Fast where it matters
For such deep wheels they pick up well, but their real
talent is for holding speed – never before have I ridden a
wheel that has made me feel so fast. Riding at 35kmh felt
like the effort of pedalling at 30kmh; riding at 50kmh the
effort of 40kmh. However, there is a trade-off. Those high
sides that cut so well through the wind head-on are also
susceptible to catching wind from the side.
Crosswinds have always been a sticking point for aero
wheels, and while the Aero 55s didn’t handle as badly
as many similar depth or deeper wheels I’ve ridden,
they definitely felt the wind on blustery days. However,
it wasn’t in a way I’ve felt before, where the whole bike
feels like it’s being buffeted sideways, but rather gusts
resulted in a temporary lightness to the steering.
At first it was disconcerting, but once I got used to the
feeling it became easy to predict and compensate for, and
definitely preferable to having an impromptu rendezvous
with a hedge. Plus, until someone works out a whole new
way to cheat physics, this crosswind issue is a necessary
evil for any aero wheel, let alone one as fast as the Aero
55s. They may have taken a while to arrive, but they were
certainly worth waiting for. ]