LOL. My DS4.5 was the same way with training wheels. He'd been begging all summer for us to take them off and I finally did on his smaller bike (He has a bigger one where he can't quite touch the ground). He was riding within the day. The same day, he also swam across the pool without his floatie.

We went to a park with good bike riding areas, along with some other homeschoolers and there was a "bump trail" (small hills, similar to what you'd see a bmx racer riding on, but much smaller.). I thought it would be a bit of a challenge for him and it was slow going the first time or two around, but once the bigger kids got out of the way and he had the track to himself, he was cruisin around it. In all honesty, his small bike is holding him back in this case...