I was at Elsinore yesteryday, and the guy parked next to me had a brand new YZ125 with only 3 hours on it. His rear hub failed at the sprocket carrier. I notice the (stock) sprocket had a radius on the inside to the mating surface of the hub. This is stupid. This would promote the sprocket pulling sideways under a load, away from the mating flanges and causing the failure. Im betting all the hub failures are with the stock sprockets. The seat on the hub isnt very wide at all, maybe 2 or 3mm from my glance. If you remove the edge of the sprocket, where in the heck is the seat? In my opinoin, its asking for a problem.