Comment by kazinator

This may be the best path: balance bike -> two-wheeled scooter -> real bike. A scooter is too hard for age 3 because it has no seat; the balance bike lets either foot instantly contact the ground no matter which way the bike is falling. Once the kid starts to coast on the balance bike, introduce a balancing scooter. That's the ideal intermediary. It allows for longer coasting with the free squarely off the ground and on the vehicle: yet offers the psychological safety of always being able to jump off. Scooters also have brakes; the kid can learn the concept of braking. That allows them to coast the scooter down hills with confidence. The main remaining challenge on a bike is starting and to some extent stopping. The way you set a bicycle in motion is scooter-like. You don't sit on it and start pedaling, but rather stand on a pedal and push off with the opposite foot. The scooter teaches this, more or less.