My son turns 11 tomorrow. (I'm getting old). I think we officially call this the "tweens", not quite a teen... sort of in between. But his bicycle isn't anymore. Kyle now fits a "big boy bicycle" and is riding a 26in wheeler. This should make the trail rides a little easier. We'll have to work on technique and fitness and see how he does. I expect he'll enjoy it more with a bike with bigger wheels that will roll over the rough stuff a little better.