The 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.
The 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.
The 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.
Because 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.
Mad 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.
Mad 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.
Aerodynamically, 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.
Mad 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.
In 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.
Enve’s 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.
Credit: BikeRadar.com Road Bikes & Gear