they probably start out on tricycles, like most little kids, then having a propensity or talent for biking, they move on to two wheeled bikes, then motored bikes as they improve their skill one tiny increment at a time.
despite this, many are injured, some seriously, and unfortunately, a very small percentage will die in the process of practicing or competing.
Do you see the odd looking clothes. They have plastic 'armor' built in. The helmets contain Kevlar as found in bullet-proof vests. I crashed a lot back when I raced. My back was run over by another bike at 60 mph. No injury other than the wind knocked out of me.
