12:52 Chain Drive Big Wheel Speed Kit #35 Chain Drive Kit 12:52 Replaces: 1000-5M-15 belt 1000-5M-18 belt 1000-5M-20 belt 35 ansi roller chain kit for: Chuweng Raser big wheel with 145/70-6 size tires and 6 inch wheels. Also FITS Xcooter Thunder, Saloor Big Wheel, Sonic Big Wheel, THS Big Wheel, Desert Storm Big wheel, Steeple Big Wheel, PanthR Big Wheel, AND OTHER MODELS using 145/70-6 rear tire. Kit includes #35 ansi chain & master link (This chain is 128 pins including master link) a 12 tooth #35 shaft sprocket and a 52 tooth #35 wheel sprocket, one 1/8 roll pin and one 1/8 inch drill bit. This 12:52 kit is a gear ratio of 1:4.3 The factory sprocket on the shaft is 20 tooth and the factory wheel sprocket is a 102 tooth 5m belt drive. The factory gearing is 1:5.1 This chain drive set is 1:4.3 For factory chain drive gear ratio of 1:5 see our 12:60 Chain drive kit for big wheel scooters. This 52 tooth sprocket is the same as oem sprocket for "The Rocky" but the shaft sprocket is totally different so this is not for "Cobra Extreme" or "The Rocky"