Re: Bicycle motor coloring?
I just don't think paint will aid in cooling. Aluminum is able to transfer heat much better than any paint would be able to.
You're cooling by passing airflow over the hot aluminum fins. The great ability of aluminum to transfer heat would be hinder by covering it up with something. Just like wearing long sleeves on a hot day. You're not going to cool off nearly as well as if you had short sleeves on. Or heck, just paint your arms and see what happens.
If you want to color the motor and not hinder the cooling capacity, you could go the oven cleaner route, or try anodizing the aluminum. That would actually be interesting. I read a while ago how to anodize aluminum yourself at home. Might be fun. My wife would probably try to kill me for it though.