I have old Mountian bike
I want to convert it to Cheep E- Bike But don't want use Convertion Kit.
I like to use an Elecitic Motor Attached to Roller
This would be put above the Front Wheel.
The Battrey and Speed Control would put in tool Box and attached to a bike Rack.
I use a Turn grip turn on and off the motor .
When Turn the Grip the Motor Touches the wheel and spins iot
'90s GT AllTerra Timberline with GM hub motor, Raleigh Competition, '81 Lotus Super Pro Aero, Schwinn S-25
I think you would be better off putting your money towards a frame mount chain drive or front wheel hub motor kit. The friction drives are REALLY old school and I have not seen any favorable reviews on them.
RC aircraft, boats, cars, robots & trucks are where most folks start looking for components to do what you describe. There' s a few things that are currently available for eBikes but it sounds like you're going for an "outside the box" design so I suggest you start with those RC model sources for other battery powered drive systems.