@nugger @Hando Its pretty true though. Energy loss from generator to storage to motor is the problem, is it not? Direct to mechanical is a good way to go, and maybe having something to capture excess power and put it into a capacitor for occasional boost (10s of power 250 at watt?) would allow a much lighter setup. Although to your point, if power could be shaved from each pedal as a nearly unnoticeable amount and passively discharged (to the wheel motor) once full, that would be even better. I think material wise, looking at seriously reducing the weight of the bike without making everything unbalanced would be a bigger boon. Wheel weight is important with electric motors, so a fixed rear sprocket would allow for more advanced lightweight and lightweight materials (titanium or aluminum rear sprocket?).