It's interesting that so many people don't know that the frame size is not the same as their wheel size. It is also interesting that so many people that don't know what they are talking about at all decide to "help" by answering a question that they know nothing about. As always, I'll have to find the answer for myself by getting the kit and then seeing first hand what I can fit it into. I'm guessing it will fit comfortably in a 20" mountain bike frame and maybe could be a tight fit in a 17" mountain bike frame.