My rear derailer,(Shimano 105) got caught up into my rim spokes,(Velocity Arrowhead-32 hole-700) and luckly the soft material that the hanger is made of twisted and sheared off. Thank God it didn't pop any spokes. That same thing happened with my Hard Rock with Specialized rims and busted 9 spokes and didn't do anything to the hanger or rear derailer.