Chainless Shaft Drive Bicycle Transmissions by Sussex
Bike chains and their associated hassles keep many people from pedalling off on the world’s most efficient form of transport. We done what we can to highlight chain alternatives, such as drive belts, hydraulics, and one or two bikes using the intriguing shaft drives. Well, now we have happened upon the folk who seem to have the patent on these shaft drive transmissions. Sussex Enterprises, of Taiwan, reckon they’ve been making then for the past 15 years but it’s only since the advent of the Shimano Nexus 7 and 8 speed internal hubs that they have started to get some traction, so to speak. The aluminium casing hides 35° bevel gears that the pedals spin to rotate an aluminium shaft, which turn turns a gear at the other end connected the Nexus hub. No external crank, no chain, no derailleur, no grease and grunge. Dynamic, one of the distributors, have a wealth on info on how it all works and they figure the eight speed option is equal to 20 speeds from a standard geared bike, plus a constant 94% efficiency is claimed from a system that needs next to no maintenance.
One other advantage is that gears can be selected without the wheels turning, great for commuting and stop-starts at traffic lights. Alas, the system is said not to be suitable for retrofits, requiring a special frame with a wider and shorter bottom bracket shell and special dropouts. But there are plenty of models available, like mountain, road, BMX and the cruiser and folder shown here. (The D-Drive by Dekra is an alternative range of three speed bikes). ::Sussex Enterprises