firstly, you only need 15ah battery if you commute 30+ miles per day or live in a very hilly area (or both), up to 20 miles a day, a 9AH battery may just do it. Secondly, you should start with a really nice donor bike - otherwise, it's no really worth the effort.670 for the cd kit and 15ah square bottle battery....may be worth it actually...plus local support?