Bicycle works without a chain

A new bicycle design uses a shaft drive instead of a chain

Most bicycles are driven by a chain. The chain transfers power from the pedals to the drive-wheel of the bike, propelling it forward. Chains are efficient and allow the use of external gears, but they stretch as the pins and rollers in the links wear and lengthen over time. Chains also rust and require continued lubrication and maintenance. Many alternatives have been through trials, including belt drives and treadles. Now, Danish company CeramicSpeed has developed a bicycle powered by a drivetrain, dubbed Driven.

The company developed the new Driven drivetrain together with the mechanical engineering department at the University of Colorado. Instead of a chain, Driven connects the pedals to the wheels using a carbon-fibre shaft. The shaft turns 90 degrees from the rear wheel and pedals. On either end of the shaft are 21 low-friction ceramic bearings. These bearings transfer torque (rotating force) produced by pedalling through the drive shaft and onto the rear cog. CeramicSpeed claims that, because the Driven drivetrain has no chain or derailleurs, it is more than 99 per cent efficient. According to CeramicSpeed, Driven creates 49 percent less friction than the leading chain and derailleur combination.

To test the driveshaft, CeramicSpeed built a prototype bicycle with a 13-gear system incorporating the drivetrain. This bicycle was one of the winners of the 2018 Eurobike Award, a yearly prize to the most innovative new products in cycling.