Derailleur hanger damage

Why Your Derailleur Captured the Wheel Spokes

You are riding along a beautiful nature trail with an incline approaching. You shift up to your largest rear sprocket and before the climb, the bike comes to a halt and the heart breaking sound in heard. “crunch!” With tears in your eyes you gaze upon your derailleur. The lower pulleys of the derailleur has captured the rear spoke wheels and rapped itself upwards, twisting your chain.