Get paint stripper (its like a gel) and in a few minustes makes most of the paint fall off your bike. Scrape the rest off witha a plastic scraper, and then wire brush the rust off and sand the frame. Then spray two light layers of clear coat (letting it dry in between the two), then when all the primer is dry sand any drips and evenly do it again. Reapeat with paint like 3 or four coats. Then clear coat it and be careful with this. If you have to sand a drip off clear coat it looks horrible.