I took a ride out to the lake this morning on my chain driven ebike. It's the one I built from parts from a mongoose electric 20" inch. I like it pretty well but frankly it needs to be at least a three speed. I think I can accomplish that by finding a 21 speed bike then removing the rear wheel but leaving all the dérailleur and crank changing parts in place. I should be able to change the gears using just the front three cranks that way.
I have it geared down so much that I have to wait until the bike is almost stopped to begin pedal assisting it.