I recently purchased a Renthal rear sprocket because I figured they are at least half the weight. I noticed after one race (300mi) that the thing was already toast. The teeth look like little shark fins instead of a triangle shape. Im really good at setting my chain tension to the proper spec so I don't think it was my fault. The package said "YZF & WR" models. What's the dealio with that?? Any thoughts? I know that you could buy a really nice steel replacement from either BajaDesigns or Krause but my stock steel sproket has thousands of miles on it without any signs of wear whatsoever so why pay mucho dinero for a steel aftermarket one?