If I roll my bike backwards, fairly quickly the following happens:
1) I hear a little 'tick' sound like a link catching on a jockey wheel or something
2) The derailleur starts to bend forwards
3) The chain gets pulled onto bigger sprockets
4) The chain gets pulled off one of the jockey wheels (the 'middle' one), getting jammed between the derailleur cage and the cassette.
Presumably it's related to my recent repair of a broken derailleur hanger which necessitated:
1) Replacing the derailleur hanger
2) Straightening a dislodged jockey wheel
3) Removing some shredded metal from both sides of that jockey wheel
4) Replacing gear cable
5) Reassembling chain, which is now a couple of links shorter than ideal, and has two power links and one of those special pins.
6) Re-mounting and adjusting derailleur, which for some reason necessitated adjusting both hi and low limit screws.
Whew. So, any ideas what causes this issue? Just the shortened chain? I'm also having a massive chain skipping problem on exactly three combinations: granny gear (26) to 2nd, 3rd and 4th biggest sprocket (32, 28, 24). It doesn't just "skip", the chain leaps off the sprocket onto a completely different sprocket, then climbs back up again.
Bent derailleur maybe?