Just two days ago one of teh training wheels on Jake's bike was loose. I offered to take it of and the emphatic "NO!" that came back had enough fear in it that I didn't even consdier trying to push the issue.
Tonight he rode with out them, right out of the gate.
I don't know what changed, but he also had been practicing a lot on the scooter. And I kept telling him, "Just like the scooter." I can't say for sure that this was really the deciding factor, but there wasn't really all that much that I taught him. So, if you're kid's having trouble with a bike, try a scooter. It seems to be a very helpful intermediate step.