I cannot sing enough praises of the wooden balance bike. We bought one for my son’s 4th birthday after he was playing with one that his (almost) 3 year old friend had. It took about 30 minutes for my son to catch onto pushing himself along the ground and (gasp) balancing . He can go amazingly fast on this, just with his own Fred Flinstone foot power. He can turn in wide circles. He can slow himself and stop (again, Fred Flinstone style). He lifts his legs up and dangles them out to the side to show off his balancing prowess.
He recently asked us when he can have a bike with training wheels.
Because training wheels would be a step backwards !