"Jim Wilkins" wrote:

http://bicycles.stackexchange.com/qu...ic-assist-bike

Electric motors being so straightforward, for example a cordless drill,
switching it out for more power should be easy enough. Especially if I
can come up with a reasonably simple and reliable way to connect the
drill spindle to the bike's "bottom bracket" where the pedal normally
would be attached. I've got the other stuff worked out (I think) and
it's under construction. That drill spindle to bike bottom bracket
connection seems the most difficult.

The bottom bracket axle appears to be very hard steel.