[foxfluff]

> High-quality drivetrains in bicycles can have an overall efficiency of up to 95%, can this system beat that?

It almost definitely cannot. I tried researching efficiency of suitably small generators some time ago but it was surprisingly hard to find useful numbers; however, I'd assume combined generator + motor efficiency won't be better than 70%. Add in conversion efficiency (for charging the battery), it's even worse.

However, that's not necessarily a problem if you consider the battery to be the primary power source and pedal power as something like a opportunistic range extender. If your battery can take you there and back, then does it matter if pedal power is only 50% efficient? I would consider such a tradeoff for the joy of not ever having to clean or replace a chain (or listen to it squeak), put it back on when it drops, or getting jeans stuck in it...