This site has rekindled my past: My first ride was on a home built. They used to take a old generator cut the casing out in the center so the armeture run against the tire. It was clamped to the two bars the are behind the seat to the wheel. Then power came from a old briggs washing machine motor 5/8 or 3/4 hp. some with kick start. Belt drive to the generator that had a screen door spring down the the axel to hold it to the wheel with a bar to raise it for a clutch. The first friction drive?
When I was 16 I was lucky enough to buy a Monark twin ran it for a couple years until the motor knocked a rod could not get parts so that was history.
Then I repowerd it with a briggs 11/2 hp belt to the rear wheel pully. Then I traded it for a model A Ford, That was the end untill I found a 60's Bike machine motor a couple years ago and got it going a year ago. Now have plans for a bunch of builds..Curt