... passCE,ISO9001 2012 best selling 20'' BMX city BIKE BICYCLEMODEL:ZY015SIZE:20''MATERIAL:alloy frameSPEED CHANGE:inner gears ... : steel and painting, thicker argon-arc welding/CO2 welding3. Bike Fork: steel and painting, co2 welding steel /suspension fork4. Rim ... buy varieties of bicycle for mountain bike, BMX, folding bike, city bike, All suspension bike, women bike, bike spare parts and other products ...