Mongoose Ledge 3.5 29" Mountain Bicycle, White, 18"/Medium Aluminum full-suspension frame and fork stand up to tough trails 21-speed twist shifters with Shimano rear derailleur for smooth shifting out on the trail Front mechanical disc brake combines with rear linear pull brake for crisp stopping and steady speed control Light and durable alloy rims support knobby mountain tires 3-piece alloy crank ensures optimal gearing and less pesky maintenance on your end