Every 125cc dirt bike we stock. The 125 class is the step up from a youth bike: enough power for real trails, still light enough to pick up. Most riders here are teens or smaller adults, and seat heights run roughly 29 to 33 inches. Both manual and semi-automatic transmissions are represented, with electric start on most models. If you are choosing between sizes, a 125 suits a rider who has outgrown a 110 but is not ready for a 250.