I have a 2 year old, and he has one of the electric quads. He loves it ! , However he keeps wanting to ride the neighbors Jr 50, it has training wheels and he is 3. What age is appropriate to let kids on a bike ? I am making my son ride with a helmet (neighbor thinks I'm anal) on the electric quad, but 3 seems a little young to ride the 50, let alone by 2 year old. Isn't 4 the suggested min age ? Any suggestions ? Or better yet , things that you wouldn't do again ?