cheap electric bike
 

I am hoping to add an electric assist to my bike (a 21speed upright road bike). I will be using a starter motor salvaged from a car and modified to take a chain sprocket. I am also going to mount a 12 volt cooling fan on the brush end, and cut holes in the endplate and the can of the motor for airflow. I don't as of yet have a controller, so I plan on starting off using a battery cut off switch as an off-on controller and use p&g.
I am trying to use as many salvaged, free or near free parts as possible.
any suggestions would be appreciated

isn't a starter really not designed for efficiency?

1: I'm using a starter because it's what I have, it was free.
2: starter motors are designed to put out large amounts of torque in short bursts. This should lend itself to pretty good pulse and glide efficiency because I plan to be driving the freewheel on the bike.

that being said, I don't expect this motor to last very long anyway, as it came out of a car with 200000mi on it and it appears to be the original starter

I work on many starters.

Not worth effort. They don't last forever they design to run for 30 sec then cool down for 30 sec then do.

They suck LOT POWER. It will drain down 500 CA battery on ford van to dead in 2 mins of crank.

I'm using a 900 CA 124 A/hr industrial battery, does that mean I would see just less than 3 min of run time till dead, or would I get more because I'm not running it at full load? most of the time I hope to use it like you said in 10-30 sec bursts to maintain speed, but the bike would already be moving. I've heard of people putting starter motors on go-karts with modest success, but we'll see what happens
pics of the motor, almost ready.

Buying a cheap electric bike has become a priority for me in the lat few months. I have seen once such item at a very closed friend of mine, and since then thinking of it seriously. I'm looking for accesibile prices, and till know i didn't find it. Anybody here can share with me somekarts for salerecommendations?

I would like to add that buying a cheap electric bike may cost you sometimes even more money than a new one. I'm about the money you will ahve to repair it, as a used one will broke very often.