Girls bike boys bike kids atb kids mountain bike model 2017 wheel size 24 inch frame material aluminium gear system with derailleur number of gears 21 rear derailleur shimano fork 50mm braking system rim brakes features luggage rack kickstand weight 151 kg crankset 170 mm chain kmc saddle selle royal frame geometry trapeze main colour black secondary colour blue recommended age suitable for ages 9 12 years brake type v brakes