Cofidis ? the only officially-sponsored Mavic team in the Tour de France ? has been using a prototype carbon wheelset from the French manufacturer.

Mavic has designed the 40mm-section rim using aeronautic fibres without spoke holes, and has added a mixed-density foam core to counter any imbalances in the inertia effect, such as with tube valves. A linear and reinforced braking surface should provide consistent braking. Moulded unidirectional full-carbon spokes bond to an aero ?faired? carbon front hub and lightweight one-piece aluminium rear hub.

Looking like a set of Lightweight wheels, rumour has it that Mavic created the new wheelset with the help of former Lightweight employee and man behind ADA wheels Cees Beers.

Several different constructions have been used and passed on to the Cofidis squad to test.

The riders? feedback will then be taken on board and used to decide the best direction of the final production wheels, which should join the range in 2008. Mavic is claiming a weight for the prototype wheels of 1,100g.