My bike is 2004 Specialized mountain bike. Bought the motor from ebay and just bolted it on. The battery lives in a home sewn bag I made which I velcro strapped to the frame. I have gone about 35mph on it. Do not recommend super high speeds unless you are a capable bike rider.
It looks like a mad max experiment. I just wanted to ride the thing and wire management is def an afterthought. I do not ride anywhere I can't take it inside with me even though I only have about $500 into it. Too much work to risk theft.
So much fun to ride. Peeling out in dirt is thrilling on bicycle.