That's a great hack. But I'm a big guy, bordering on 285lbs. That kind of low power traction doesn't seem enough to move me. I know European 250w motors are never enough for me.

I've build my first ebike a few months ago. I went for a 1000w Bafang mid drive geared motor with a 48v 20a battery, on an old used Peugeot mountain bike. Adding some new/used bike parts (wheels, tires, chain and rear gear), total project cost arrived at C$1800, less than half the price of a new ebike with similar specs.

Considering my weight, 20 to 23 kph is my speed of choice in pedal assist mode, which is quite safe. It does extends my range a lot compared to other use cases.