[Closed] bent back derialleur

If the actual derailleur is twisted then time for a new one. Are you sure it's not the mech hanger that's twisted. If so they can be straightened or if necessary replaced.

Sometimes you can straighten them- it might be one part that's bent, like the links at the top or the cage at the bottom, which is visibly bent and you can just bend it back. Or it might be the hanger that attaches it to the frame too. But if it's one of the central bits, you don't have much chance of getting it properly straight.

So plan B is, don't worry too much about properly straight. Thing is, a bent mech is pretty much for the bin anyway so you can't lose by making it worse- so you might as well try and make it better. For me this just means bending it by brute force and eyeball and seeing if it works. I've got a lot more life out of some mechs this way. it'll never be perfect but actually mechs don't need to be perfect.

(just make sure you don't break the mech hanger while you're at it!)

yes straighten or replace mech or hanger.

new bike.

any suggestions for a new derailleur?

thanks for the advice
i have tried to fix it with a bit of force but even then if i shifted into my 1st gear, the rear derailleur hooked onto one of my spokes and stopped me, hence the need of advice on a new rear derailleur (and mech... probably?)
thanks again

You need to buy or borrow a mech alignment tool.

Remove the rear mech and screw the rear mech alignment tool into the rear mech dropout.

There are a few videos online, have a look and see how to straighten the rear mech dropout.

You might break the dropout if you are a bit hamfisted, always good to have a spare rear dropout in your spares.

Once this is straight, refit the rear mech.

If it still is troublesome, then the mech is the problem , have to be a new one to fix this.

Alternatively, your lbs can fix this, but it's worth being able to do this yourself really.

Was looking at hanger alignment tools yesterday. Didn't want to spend £200+ on Shimano's offering. Park Tools one seems difficult to get hold of. Got the lifeline/x-tools/etc one that's reviewed as a bit imprecise for £32 - but it's apparently no good if you have a thru-axle (I don't).

Any decent bike shop will have an alignment tool & do it for you

thanks
if that dosent work, i just trash the back derailleur for a new one?

Not necessarily. You need the hanger straight before you can properly check the derailleur. To be clear you seem to suggest above that mech and derailleur are different. 'Mech' is slang for derailleur and the mech hanger is the small piece of alluminium that the derailleur bolts to which in turn bolts to the frame.

The hanger is seperate from the frame and designed to bend/snap saving an expensive frame repair. It also often bends saving the rear mech.

if the mech is properly twisted should i try a bit of brute force or just take it for a servicing ?
thanks again!

You will struggle to straighten a mech without damaging the hanger.

Try a vice.

No offence but your questions suggest this is beyond you just now, Google the topic and look at some videos.

thanks

Picture??