If he wants to ride Trials, he should really be on a bike built for it. BMX will be a good starting block in the way you need to move, and bike handling, but he should really be riding the correct bike to do whatever it is that he wants to do.


One good way to at least get a feel for the proper riding would be to get some disc brakes on there somehow. That would give him the proper braking-feel. And if his bike has a freewheel, theres a chance that you could get something down to 13 teeth. But that really depends on the hub.