Balance bike is the way to go also because they are so much lighter. My younger daughter rode the balance bike since she was two and zipped around in the neighborhood easily. My older one never enjoyed her heavy Schwinn bike much until she was almost 4.5 when I took the training wheel off (I didn't know about balance bike until later) and her legs were long enough to reach the ground .
It took half an hour for my younger one to get used to transition to a regular bike. Now at 6 she has plenty of energy to spare after 10-mile rides with us.