I may have jumped the gun a bit. This past spring Hank, at the ripe old age of three, jumped on his sister's 12-inch bike, without training wheels and wanted to ride. I had my doubts as to his ability but I allowed the dream and little Hank proved my doubts wrong; he could do it! But then he didn't. He jumped back on his bike with training wheels and said, quite stridently, that he didn't want to ride his bike without training wheels anymore. Joe and I didn't push it.
Just last week Hank came whizzing out of the garage, once again atop his sister's pink and purple 12-inch two-wheeler. He was determined to keep up with the big kids on the block and he asked us to take the training wheels off his 16-inch bike. We did, and he hasn't looked back since (well, except in the last picture, where he kind of looks like the mushroom character from the Mario video games).