About this item Black 2.4L Gas Bicycle Frame (Aluminum Alloy) Disc Brake and V Brake Requirement for seatpost:27.2mm; Required for seat post clamp:31.8mm; Requirement on headset size: 1 1/8″; Requirement on petcock size: 10*1.0mm Head tube: 150mm; Rear Width: 135mm; 38mm diameter downtube 70 degrees angle V frame; Bottom bracket 2″ diameter PLEASE NOTE 1: The best safe speed if racing: 35km/h; If buyers’ bike rear wheel is with quick release, we suggest buyers do not buy the gas frame unless buyers are professional