I think I've bent my rear derailleur/hanger...

I went to shift up a gear whilst out riding this morning and the chain came off. After putting it back on I couldn't shift at the back atall. The shifter doesn't even click when going up. It clicks down but really loosely and doesn't shift atall.
It appears to me that the real derailleur is bent. Or the hanger. Would this cause it to not shift atall as is happening?Theres a photo, though I'm not sure if that will help.

I don't recall bashing it but it does have a big scratch on that I've never noticed before. If it is bent, can it be fixed (by me) or do I need a new RD and/or hanger? Or could it be something else?
Thanks in advance, and don't be afraid to be patronising as I'm really rather inexperienced with the mechanics of my bikes

 

Hi Joe

According to Sheldon Brown website on this very matter - which I read recently as I had a gear problem.

http://www.sheldonbrown.com/derailer-adjustment.html

His advice is that rather than bend it out, the deraileur should be removed in order to straighten the bracket:

 

yes, i've had a bent mech hanger straightened by an lbs before.

 

It's a replaceable hanger, your LBS should be able to get you a new one.

 

If you want to bodge it (and the gears may not shift very well, so consider it a temporary solution) remove the rear mech, grip the hanger with a big adjustable wrench and bend roughly back into place. Don't mess around with it, because assuming it's aluminium it will end up snapping.

The better and permanent solution is to remove the rear mech, remove the rear mech hanger and take it into a local bike shop. Unfortunately most brands use their own proprietary hangers - in fact most brands use a variety of designs for different models so the odds are the shop will have to order it. If you want to buy online are are sure of the make/model/year then try Betd.

 

You need to take it to the shop, with the rear wheel for them to check the alignment and straighten the hanger if necessary.

If you are anywhere near Blackburn, Lancs, I have the tool and can do it for you!

 

Thanks for the advice people. And cheers RR but I'm nowhere near.
I've gone singlespeed for now anyway

 

Actually I went singlespeed on my Trek for similar reasons - not an entirely bad thing I may add!

 

I also went single speed on the commuter one day this week due to a mechanical problem and was suprised how hills, that I normally change down on, can still be ridden quite easily if you start to honk!!!!!!!!!!!!!!!!!