Absolutely the key is to get your cihld a bike that is too small, like comically too small. The idea is if they feel themselves falling, they just stand up and the bike can roll out from under them.
next locate a safe place to bike that has a gentle incline. It doesn't have to be on grass if the bike is small and the incline is gentle. Stand the child at the top of the hill, sit him on the bike, and have him just scoot himself down to the bottom of the hill. No use of pedals at this point, just scooting (think Fred Flintstone car).
Gradually encourage your child to lift his feet off the ground as long as he feels like it. You could encourage him to count how long his feet ar off the ground...3 secs, 5 secs, ten seconds. The gentle incline should provide enough speed to keep him balanced for longer and longer periods of time.
All of this can be accomplished without removing the pedals from the bike if that's a pain. ust tell your child to keep his feet away from the pedals.
Your child will develop a sense of balance this way. When he's ready, you can raise the seat a bit, but stay on a small bike and move him to a flat, large area. Bike trails and sidewalks are no good for this next step as your child can't worry about going in a straight line. Church or school parking lots on a Saturday are a good place.
Still on the small bike have your child bike with you holding the back of his shirt and run after him. He can still scoot if he wants or you hold him and provide the motino while he pedals a bit. this part can be frustrating. It might help your child to practice pedalling on a stationary bike first, and it also helps to watch some YouTube videos of kids learning to bike.
After your child really masters biking while you hold him, then let him bike on his small bike around the parking lot. Don't think of graduating to a larger bike until he is very comfortable with a small one.
