I don't think a quad-copter motor would have near enough torque for that size wheel, and the rpm would be way too high without some gear reduction. It's just a Cruiser with a sidecar that operates at city speeds, has to be able to start/stop alone. You're not building a race bike this size. Well...you might, but i'm not gonna!
I really like the 1/18 scale American Diorama biker figures
https://americandiorama.com/index.ph...th=69&limit=50
I like 'Angel' better, but 'Bulldog' or 'Ace' would probably fit better for actually riding it.
At the same time i got this one, I'd also picked up a Harley Servi-car (meter-maid) style 3-wheeler. Thinking it'd be cool to livery it up to be 1930-60s gas station / mechanic shop gopher. Or i could biker it out, since somebody has to bring the beer to the party.