I always thought the F1 kinetic energy recovery systems (KERS) were a pretty neat mechanical solution. Probably way too heavy for bikes & low-torque humans, tho

I always thought the F1 kinetic energy recovery systems (KERS) were a pretty neat mechanical solution. Probably way too heavy for bikes & low-torque humans, though. https://en.wikipedia.org/wiki/Kinetic_energy_recovery_system https://en.wikipedia.org/wiki/Kinetic_energy_recovery_system