Regenerative braking often doesn't pay off. Note that you don't need a whole lot of energy to put your bike into motion, while you need quite some energy to kee

Regenerative braking often doesn't pay off. Note that you don't need a whole lot of energy to put your bike into motion, while you need quite some energy to keep it moving due to friction. Putting in numbers, if you go 5m/s=18km/h=12mph, your kinetic energy is 100kg*(5 m/s)²/2 = 1.25kJ, which at 125W can power you for ten seconds. You can cast longer than ten seconds in front of a red light in most situations. And keep in mind that for regenerative braking to work, you must walk twice through the whole efficiency chain, which is generator -> electronics -> battery -> battery -> electronics -> motor), giving you an efficiency of about 0.85^6=37%. So 3.7 seconds.