> The Free Drive system works by converting the rider’s pedaling power into electrical energy via a small generator housed between the pedals. It then delivers this energy to the rear wheel (or wheels) via cables strung inside or outside the frame of the bike, rather than sending it mechanically through a chain or belt. Excess energy created by pedaling is fed back into the battery. The end result is a power system with fewer moving parts to complicate construction.
https://www.theverge.com/2021/9/2/22653697/schaeffler-free-d...