A pedal go-kart is not a bicycle, and questions about conversion, should realistically be directed at Berg. Converting a single speed bicycle to multi-speed however, is as simple as converting multi-speed to single. Your thread title is misleading, and I had to actually look up what machine you were talking about. Maybe someone has experience with these, and can help you, which would be great, but this forum is not really the place to look for help. Not trying to be rude, just don’t understand why you posted this here. Possibly the recumbent sub-forum could be of better help.