actually i have a non-threaded bb the same size as a bmx bb.. so I just tapped the bmx cups into it. But, there is a newer bb in bmx called a "euro" bb and its smaller and threaded.. but i dont know it the threading would match up with a road bike bb shell or not. I ended up hooking up 3 piece cranks, a chainwheel, and a bb for like $60 with the bmx parts.