At Eurobike in Germany, CeramicSpeed has unveiled its cutting edge development, a new type of bicycle drivetrain called DrivEn. And it attracted natural attention from visitors, especially after the developers modestly stated that they reduced friction by 49% compared to a classic system like Shimano Dura Ace, which still uses a traditional chain.
DrivEn does not have the usual chain, it has been replaced by a carbon fiber cylindrical shaft, on both sides of which are mounted sets of ceramic bearings. There are 21 of them in total, all with an extremely low coefficient of friction. The principle of operation is simple: the front module receives torque from the pedals, the shaft rotates, spins the rear module and it transmits rotation through the teeth on a flat cassette on the wheel axle.
The teeth are arranged in rows, the pitch between which corresponds to one of the bicycle speeds. To switch between them, a servo drive is used, which extends the shaft piston, moving it to the desired row. Alas, this function was not shown in the prototype at the exhibition, it will be implemented a little later. Which doesn't stop the Director of CeramicSpeed from stating "We've built a 99% efficient multi-speed drivetrain, no more naughty chain and complicated derailleur."
Friction reduction is achieved by eliminating the 8 key points of contact from the classic transmission. These are where the chain goes through the sprocket, cassette and derailleur. The fact that the new architecture is really interesting from an engineering point of view is evidenced by the 2018 Eurobike Award, which was immediately given out. The main developers of DrivEn are design engineers at the University of Colorado.