My (just turned) 8 year old who is at the Asperger's end of things, wasn't into biking until recently. We took his training wheels off and the pedals when he was about five because he would ride all the way to the side and he wasn't getting anything out of the training wheels other than how to ride inappropriately. He didn't really like scooting on the bike but he loved a razor scooter. So he rode the razor like a maniac, and I knew he could balance, then about six months ago he started scooting on the bike a bit and kind of expressing interest. What I've found, at least in terms of riding independently (because we did have a trail a bike that my husband rode with him from 6-7 about twice per month) was we had to wait until he wanted to ride. What made him want to ride was the fact that others could and he couldn't. I was, however, afraid to teach him myself because if he fell it would be all over. So we took advantage of the lose the training wheels class that exists in various parts of the country (we're in Portland), and for kids with disabilities it's a week long. In any case, my kid graduated to riding on his own within the first hour of the program and spent the rest of the week riding around and practicing his skills on the street and sidewalk with the trainers. Now he's riding with me 2-3 miles at a time around the city (using bike lanes) with no problems other than we need to buy him a larger bike (which is why we're only riding short distances--it's mainly to practice in the bike lanes). So, the point of this story was to say that if you want your child to ride independently and not with a trail a bike, you might have to wait until there is actual interest from the child, and I'd also heavily recommend the lose the training wheels program!!