What weight and what speed?

I have canti on my tandem, which can be 500+lbs loaded for touring, and easily go 40mph in hilly terrain. Good brakes, good pads are better than cheap disk brakes. of course BB7 are the bomb.

Regen doesn't make sense on an e-bike. That is for an e-moped. Nothing wrong with that, but you are not going to want to pedal a regen bike.