A 20” size wheel fat tire bike is finally available for all fat tire lovers. The smaller wheel design allows the youth to experience what they could not experience with the adult size Mammoth fat tire bikes. But this is not only for the youth! We added a component called –risers” on the headset that allows riders to remove or install conveniently that adjusts to oneês height preferences. It supports youth and adults to just the right fit for an enjoyable comfortable ride. Donêt let the small wheel fool you with its 20” size wheels. The Mammoth-S has thick rigid knobby tires that can rip through all terrain just as the adult fat bikes can. Simplicity is key to this Jr. Size fat tire bike. With its 7-Speed Shimano rear derailleurs this beast can climb uphill and breeze through down hills in snow and sand. Experience the productivity of these disc breaks by slowing down and stopping with full control. This bike is for youth and adults that enjoy a great time outdoors.