If your under 5 years old then you need training wheels or you can help you son to they will lean how to ride a bike. If want to ride fast you have to pedal fast or if you have gears you can lose it. If your scared and you're going down a long hill then you can lose your gears of brakes. If your going up a hill if i was you i will lose my gears or get a mountain bike. At the end they know how to lose their gear and there breaks when they up and down.