DIY Electric Bicycle, Entry #2: Finding A Motor

The heart of this project is the motor that drives the bicycle. Due to all the weight it would have to move, I needed a powerful 12 volt motor capable of producing a lot of torque. My first idea was to use a motor from a treadmill, but that hope quickly faded away--treadmill motors generally use 130 volt DC motors, which was too much for me. From there I started thinking more about motors that can be found in cars. I figured that they are generally in high-torque applications and ran on 12 volts--ideal for this project. Unfortunately, most of the motors I found were fairly small and would not work to power a bicycle. However, then I started looking at the engine. The first thing that caught my eye was a relatively large motor with the shaft going inside part of the engine.
I guess I should mention right now that I do not know very much about cars. I didn't know much about this particular motor, but I figured this was the starter motor. It turned out I was correct. This motor seemed to fit my needs. It ran on 12 volts and was capable of producing a large amount of torque. So, before doing anything else, I decided to do a bit of research....