Personaly I am inclined to blame the Ironman sprocket. The same thing happened to me and my buddy. We both had Ironman sprockets. Both broke after landing from a jump while on the gas. My theory is that under extreme pressure the skeleton frame of the ironman folds to one side creating the chain of events which leads to the broken hub. I will never buy another one. it would be interesting to see if there is something to this as this is the first ironman sprocket i have had. i have never heard of this happening though. and i definitely wasn't on the gas hard when mine broke.