Getting rid of the training wheels

It was only a matter of time before it happened, but the other day I decided to take the training wheels off of Joshua's bike. It was surprisingly easy to get him to get to go by himself, just a little push to get him going and he was on his way. None of the running and following and holding on to the seat that you would expect from the first steps of learning to ride on only two wheels.

What probably made the most impact on the speed of his learning is the fact that he is already quite proficient at riding a scooter. This provided the needed balance for the transition to the bike. He was hesitant on turning, having to stop before pushing his bike to turn it around, but once he figured out that he could do it without stopping, he is going crazy. Up and down the curb, figure 8's. Next thing you know, he is going to be doing wheelies and other tricks. The only thing he needs work on is the starting. Just a little help and a push and he can go and go. Why do they have to grow up so fast?