I am another one for the balance bike. We bought one for our oldest son back when he was turning 2. He is going to be 5 in August, I took the pedals off of his pedal bike 2 weeks ago and you can totally see the skills he learned from the balance bike. The only times he has crashed is when he lost focus.
Our younger son who is 2 right now is on the balance bike now and keeps up with older brother on his pedal bike. I have to use my bike to pace them.
Lots of fun.
Glenn