Completely New Bike Drivetrain May Change The Definition Of “Bike.”

By Tom Martin

September 02, 2021



Batteries on bicycles are already changing the transportation scene significantly. A new generator-based method of transferring pedal power to drive wheels is being developed by German component makers Schaeffler replaces the bottom bracket with a generator and eliminates the need for a chain, and possible gears/derailleur. It is 5% less efficient than straight line chain drive, but by “cutting” the mechanical alignment of rider and rear wheel, it allows innovative packaging options that couldn’t be delivered with conventional chain drive. This effectively reinforces the point that some companies see bikes as a very broad transportation category. If we consider that e-bikes make cargo bikes a practical reality and “slow motorcycles” (e-bikes requiring little or no rider power) are another, and scooters are a third, then the part of cycling many of us know and love (recreational bicycles = road and mountain bikes) is just a part of what is being revolutionized. A 5% efficiency loss isn’t ideal, but in the context of e-bikes is in the category of a small amount of weight or bad aero or rolling resistance. If so, being able to do packaging where the rider/pedals do not need a straight line connection to the rear hub might give packaging freedom that is useful (low CG child/dog seats or trunk or side by side seating behind rider?). And with batteries on board, the 5% is something the user will experience as range reduction, not an all-the-time riding drag.


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