Nice bike and kid. Definitely let him ride the 50, but not in the street. I was stopped at a light last week, when I heard a strange noise next to me. It was a young boy on a pocket rocket between me and the curb. I was shocked that he could sneak up on me, and I was surprised that he had no helmet. His head barely came up to my seat. I didn't know what to say, but told him he should ride on the sidewalk. The light changed and we were both gone.