The remit for Shimano engineers was to create a new wheel for clincher tyres with a strength-to-weight ratio that equalled that of a 100 percent carbon wheel. They also had to be affordable, and have the superior performance of an aluminium braking surface.
To do this Shimano has employed a new jointing process. This enables the fusing of an aluminium extrusion of half the normal thickness for the braking surface and well of the rim to a carbon fibre mid section.
Additional layers of carbon material are applied to the rim around the vulnerable area of the spoke holes, and these are offset to one side on the rear rim to minimise the dish that is inevitable on all wheels that use derailleur gears.
Shimano remains true to traditional cup and cone ball bearings in the hubs. They can be be stripped and re-greased. There are changes to the hub body to improve reliability and, Shimano claims, strength, by using more pulling spokes than with the previous model. There are also improvements to the seals to make them more weather-resistant.
Shimano has also ditched the dedicated 10-speed freehub body in favour of one that can also be used with earlier 9-speed Shimano cassettes. The new freehub body is claimed to provide 125 per cent faster engagement.
These wheels give the Mavic Ksyrium SL Premium and Bontrager Race X-Lite a run for their money with their stability at high speed. But it’s on the climbs that they exceed expectations and where they are directly comparable with wheels costing more than twice the price.
Confusingly the Dura-Ace moniker is also attached to Shimano’s Scandium-rimmed wheels for tubeless and clincher tyres and there’s a Dura-Ace wheel with 100 per cent carbon rims for tubular tyres.
Shimano wheels can be made Campagnolo-compatible by using the Evolution cassette that fits onto the Shimano-type freehub splines (available in 12-25 and 13-28 combinations for £32.50, from Byercycles www.byercycles.co.uk).