My 7yo is within an inch of the 9yo so the youngest gets double the hand down bikes. So mine only have to survive 2 kids. I made the mistake of buying used trek 220 which are hopelessly heavy but at 2 for 50.00 it's not a big deal. Just meant new bikes from Santa since both took to the trails and pump track. Just means the treks make good ride to school bikes since those get kicked around at the racks by everyone and the nice bikes only get scratched and dinged by the rocks. Having kids who love bikes is a joy to keep up with though.