Riding two wheels at 4 years

Ashby learned how to ride his bike on Saturday. He never did have training wheels. It was a nice enough day so he said, "Daddy I want to ride my bike today." Brian took him to the park to practice gliding down the hill, but then the kid just took off on his own.

I can't get over just how amazing he is. How does he pick up on things so quickly? And how is he so coordinated?

Its only been a couple of days, but now he's a bike riding maniac.