I've had this idea for a while but only recently found a place where someone else had done it online. I was thinking of mounting a starter motor from a car onto a bicycle and power it with ATV batteries. I've got my bike, motor and I've started to build the lifting lever to take the motor off the tire. Yes, the motor will actually be rolling on the tire, i did this to minimize any gearing i'd have to do by attaching it to the sprocket. I'll use a knurled cylinder to replace the sprocket on the starter to keep grip on the tire. The rider will still be able to pedal and if they have the motor down on the tire and they can recharge the battery by pedaling with the regen braking. Instead of a controller I'm going to use a switch and 2 12v batteries. The switch box will have an on/off and a 12v/24v switch in it so the rider will first have to get the bike up to speed then they can engage the motor and keep a current speed. I'm hoping to have it done before the end of January but I'm doing it as a school project. The cost so far: $0
. I'll try to get pics up soon.