Renthal – Renthal Rear Sprockets - Twinring - Yamaha, including 99-24 YZ125/X/G, YZ 250/F/X, YZ450F/FX and WR250-450F Twinrings in blue, black and silver, plus 99-05 YZ125-250F and YZ400-450 fitments that also cover the 88-89 Honda XR 250R. Yamaha's four-stroke torque is exactly what shortens sprocket life, which is why so many YZ450F and WR450F owners move to a two-piece design. The hardened steel tooth ring takes the chain load and the alloy carrier keeps the weight close to a solid aluminium sprocket, so acceleration and suspension action stay sharp while the wear surface lasts far longer. Popular 48P and 50P ratios cover both worlds: a slightly taller setup for fast, flowing tracks and a bigger rear for woods riding where second-gear traction matters most. With teeth that resist hooking, chain adjustment intervals stretch out and drive feels direct off the bottom, which is what makes a YZ or WR easier to ride smoothly. Blue anodized carriers finish the build to match Yamaha bodywork. The longer service life is exactly why many riders accept the small weight penalty of a two-piece design over solid alloy gearing.