Originally Posted by
HillRider
Well, among the "old and crabby" are most state's DMV's that consider motorized bicycles, particularly those with gas engines, a motorcycle and subject to the same licensing, registration, driver's license endorsements, etc.
It depends on where you are. Some US states don't allow them but many police still see it as a matter generally not worth their time unless the rider is being very silly and the police officer has little else to do.
Also, most states are old and crabby enough to forbid motorized bicycles on MUPS.
Yea, but,,, again, it depends a lot on the rider's behavior.
Really however--the more I've read, I'm tending to believe that OP won't find anything suitable in a bicycle engine--either gas or electric.
The best bet is a BIG front hub motor, with a big capacity battery. And that ain't going to be lightweight, or cheap.