... kits turn your normal Mountain Bike into Snowmobile/snow bike.Rear wheel drive,Front ski.Installed easy,remove quickly Starting a new ... first step: the rear wheel drive kit which consists of a composite wheel with a polyurethane track swaps out the rear wheel,adds grip on ... the snow or soft sand!component :1, rear wheel drive kit: consists of a composite wheel with a polyurethane track.2, front ski ...