I don't know about it being a different balancing skill. A few years back when my son was on training wheels, he also had a two-wheel scooter that he liked to ride around. Somehow he taught himself how to balance it as I saw him push off to get it going, then kept his foot up as he rode it around. I knew that he would transition easily to a bike, and the day we took his training wheels off it took less than 5 minutes for him to be riding around on his own.

My 7-year-old daughter, on the other hand, doesn't want me to take her training wheels off and is a bit timid about learning to ride. My plan is to remove her training wheels & pedals and to teach her how to balance just by coasting down a small incline. But she's going to have to want to do it. Convincing her might not be easy.