I am looking into buying a 50cc bike for my 4 1/2 year old. He is about 36 inches tall so I would think even the bikes with seat heights of 21 inches would be a little big. But was planning to put training wheels on it. Leaning towards getting a CRF50. Any advice/experience with putting the little guy on the bike for the first time - think he would be ok on the CRF50?