If your a frequent rider dont be suprised that the rear brakes on you. That is the most delicate part of your bike and there are many variables on what could cause the damage. This is an ongoing problem in the mountain biking world. You can try a shorter cage but you may not be able to shift to your larger rear sprokets while on your largest front sproket. You also should check the alignment of the sprokets and the hanger to see if it is lining up with your cassett each time you ride. I hope these suggestions help.