line between genius and madness may be a thin one but from the clever design of
these wheels you could argue that this brand chose the wrong first word in
their name. Mad Fiber describe their design as being ‘carbon optimised’, by
which they mean that the wheels are designed around the properties of carbon
fibre as a material instead of using it to replace the metal components in a
traditional spoked wheel. If you really want to geek out on the tech, it’s
explained really well on Mad Fiber’s website. The first Mad Fiber wheels
debuted in 2010 as tubulars and last summer we saw prototypes of a clincher
version, which is finally here. 

three-piece construction – two sidewalls and the tyre seat, made separately
then bonded together – used for the original tubular wheels made it relatively
simple to convert the design to clincher by swapping the tyre seat. Owing to the
outward force exerted by a clincher tyre, Mad Fiber opted for an aluminium tyre
seat, but with the carbon fibre sidewalls bonded over the top so that the
braking surfaces are carbon. At this price it probably also matters to some buyers
that the wheels look ‘full carbon’ and therefore entirely premium.

spokes are flat, five-ply strips of carbon with 12k layers on the outside of
three unidirectional layers, the fibres of which are aligned with the spoke’s
length to provide exceptional tensile strength. The spokes are bonded to the
hub flange and the inside of the rim sidewall with ‘paddle’ shapes at each end
providing larger bonding areas for the aerospace adhesive. The numbers don’t do
justice to the strength of this construction, but suffice to say that if this
glue were prone to failing then planes would regularly fall out of the sky.

the spokes are of a fixed length and there are no nipples with which to add
tension, the wheels are made flat with the spokes parallel. The flanges are
then pulled outwards and a spacer is inserted to tension the spokes evenly and
simultaneously. A new feature introduced on the clinchers is the one-piece
construction of the rear drive-side spokes.

Fiber sell their wheels with a four-year warranty and a ‘nominal charge’ crash
replacement policy. They come with titanium quick-releases, valve extenders and
brake pads. Tyres fit easily, with a positive click into the alloy rim making
it easy to get them seated properly.

As you’d expect from a 1,318g wheelset, they feel
light in your bike from the first pedal stroke – all the more so because
they’re noticeably stiffer than any conventionally spoked wheels. The extra
rigidity makes them even keener to accelerate and their performance in the
most testing situations, namely sprinting and climbing, is outstanding. There
is no other 60mm clincher that comes close. They ride smoothly too.

Fiber supply their own pads made with cork and rubber and insist that they are
used, otherwise the warranty will be void. The braking is okay in the dry but there’s
a big delay in the wet before adequate power arrives. This is something that
needs development, either to make the rims able to withstand the extra braking
force of SwissStop Yellow Kings or to use the aluminium tyre seat for the brake
track instead. The stopping power is no worse than many carbon wheels we’ve
ridden, but it’s some way behind the best.

the clinchers are identical to the tubular version, which is to say that
they’re different from most other wheels on the market. The skinny shape is more
a product of the construction concept than wind tunnel tuning. Mad Fiber claim
very low drag in smaller wind yaw angles, where the skinny shape is effective
at slicing through the air, and this was certainly borne out in our testing.
Into a block headwind and especially in still air, they feel really fast.

Fiber admit that this rim shape stalls earlier than most, with drag increasing
significantly from an 8-10 degree wind yaw angle but gradually declining again after
that. Mad Fiber claim that these wheels are especially fast from 20-30 degrees,
but the fact that no one else tests beyond 20 degrees tells you all you need to
know about the relevance of such extreme figures – you’d have to be riding
slowly in a howling crosswind to create such an angle.

crosswinds on the road they don’t feel as fast as wide profile wheels such as
Zipp 404 Firecrests or Enve’s shallower 3.4s. What’s more, gusts, passing trucks or gaps in
hedges can produce heart-pounding instability.

The shallower Reynolds RZR 46 is an obvious rival in
terms of construction and performance. But it’s far more expensive (£3,999) and
only available as a tubular, so it’s barely relevant that the RZR is stiffer and
far more effective in a range of wind conditions than the Mad Fibers.

recently launched 6.7 and 3.4 clinchers are probably the closest rivals, being
similar in price and lighter than other aero clinchers on the market. The Mad
Fibers are lighter and stiffer than both, plus they’ll never go out of true,
but even the shallower 3.4s give better all round aero performance, especially
in crosswinds, so that’s the choice you have to weigh up. For circuit races
likely to end in a sprint we’d go for the Mad Fibers, but they’re not quite the
best do-it-all clinchers on the market.

This article is compiled from reviews originally
published in Cycling Plusand Triathlon Plusmagazines,
available on Apple Newsstand and Zinio.