Any one see this

Gives me ideas.
I could chuck half the video with a goped clutch drum bearing with 12mm thread stub.
I like the clutch, better than what I did.
I wanted to try belt drive on mine, the 2-stroke smoked chains, but I got my etrike and chucked the FD.

The advantages are better torque with larger rollers.
Disadvantage? Added friction and load. Frankly when I did a direct drive with the same engine, it ran circles around my avatar bike.
Clever and skillful to make that with hand tools. The clutch is redundant, lift the motor off the tire, that is the clutch. Get it rolling drop the motor on the tire and away you go.
A fair weather set up, a wet road and your friction is gone.