Looking for McGyver (Cross Post)

[Fumesucker]

6. A shade tree motor drive is a major project, there's a lot to get right

A bolt in front wheel motor drive would be your best option but we are talking $500 before you start riding most likely and I get the impression you don't have that kind of money (I don't either right now).

If I were you the first and cheapest option I would try is get a bike with 6 or more gears and pedal in a very low gear. You have a single speed which means you are having to push the pedals hard. I have painful knees if I push hard too, so I gear down and twirl the pedals rather than mashing them. Considering your size I'd look for a kids 20" mountain bike with gears, 6 should be fine on a bike that small. I see them at our flea market every month or so. 24" bike is hard to find, there are a lot more 20" and 26" than 24". Extended seatpost and handlebar support will get the seat and bars where you need them. The smaller bike will have a shorter stroke on the pedals so you won''t have so much motion for your knees.

The longer you wait to get an ebike setup the better they will be and the less they will cost, it's like cellphones, getting better very quickly. Don't be impatient if you can possibly manage.