I still got to confirm but I think I've twisted the rear mech on my commuting bike, it took a nasty bash yesterday. It seemed OK after I untwisted it but I'm not sure if it is index to the correct gears or goes to the the extremes, ie largest or smallest cassete. It was too dark and wet this morning and I never had enough time to confirm. If it is twisted how much damage does it do the bike or will I be able soldier on for a while? btw I think its a Shimano Deore Top Normal in the 500 series perhaps a RD-M511.