He loves to play and really wants a bike. However he does not have enough balance or stability to ride a bike without training wheels and now that he is bigger, I can not find a bike that he can ride and that I can trust him not to go anywhere that could potentially harm him.

He loves to play and really wants a bike. However he does not have enough balance or stability to ride a bike without training wheels and now that he is 4'10 and 125lbs at 9 years old I can not find a bike that he can ride and I can trust him not to go anywhere that could potentially harm him.