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Bent chain ring

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 TobyA 08 May 2014
I bent the outer chain ring on my MTB's crankset at the weekend hitting a rock. The chain will no longer stay seated on it as once the revolution gets round to the dinged bit it drops it back on to the middle chain ring. I'm not very precious about the bike, it's my well used bump around in the woods hardtail, but I actually replaced the whole crankset no so long ago so I would like to get more use out of it.

I haven't even looked to see if you can buy a replacement chain ring as it's just an Alivio Crankset - so not super expensive, but was wondering if anyone had had any success getting a kink out of chain ring on their own with the application of brute force of some not very advanced kind?
 Chris the Tall 08 May 2014
In reply to TobyA:

When are you going to Sheffield Hallam (or have you been ?)

I have a couple of chain rings I'm about to throw out. Whether they will fit is another matter, and of course they are well worn, but they might be of use
Removed User 08 May 2014
In reply to TobyA:

How big is the kink? I would have though you could place it on a flat block and tap it back gently with a lump hammer?
OP TobyA 08 May 2014
In reply to Chris the Tall:

Been Chris - super brief visit last week but they've offered me a place for Sept. so me and the family might be moving that way - still to decide, big difficult decision etc! But thanks for the kind offer.

Hardonicus - I was thinking along those lines but wondered if anyone had tried and met with some success?
 woolsack 08 May 2014
In reply to TobyA:

Put it onto a block of wood and if you have a copper hide mallet or something sympathetic to what I presume is an alloy chainring, give it some hammer love

In reply to woolsack:

The usual advice for bent brake discs is to straighten them using a large-ish adjustable spanner tightened right up on to the edge. Maybe this would work for a chain ring as well?
 Bob Hughes 08 May 2014
In reply to TobyA:

you definitely can buy a replacement chain ring - probably cost you 20 quid max. Or bend it backinto shape, although I would think you'd be better with the jaws of an adjustable spanner than with a hammer.
 nniff 08 May 2014
In reply to TobyA:

A third vote for an adjustable spanner - worked for me
 Kevin Forde 08 May 2014
In reply to nniff:
The great Sheldon endorses bending them back into shape too.
http://sheldonbrown.com/straighten-chw.html
 Timmd 08 May 2014
In reply to TobyA:
A shot peen hammer and or adjustable spanner has worked for me in the past. I forget if I used both or one or the other at different times, but you can bend them back again.
Post edited at 17:30
 peebles boy 08 May 2014
In reply to TobyA:

Take it off, lie it on something hard and flat, hit until desired shape.

I'm still running an Alivio outer big ring that I brought back from a near ninety degree bend that was returned to shape with liberal use of a big rock whilst out biking over three years ago.
 Timmd 08 May 2014
In reply to Bob Hughes:

> you definitely can buy a replacement chain ring - probably cost you 20 quid max. Or bend it backinto shape, although I would think you'd be better with the jaws of an adjustable spanner than with a hammer.

Yeah, a adjustable would be more precise.
OP TobyA 08 May 2014
In reply to peebles boy:

> I'm still running an Alivio outer big ring that I brought back from a near ninety degree bend that was returned to shape with liberal use of a big rock whilst out biking over three years ago.

That's what I wanted to hear.

Thanks all! I will give it a bash - literally.
 wilkesley 08 May 2014
In reply to TobyA:

If you have a couple of G Clamps and some hard wood blocks, or steel plates, you can probably bend it back by making a "sandwich" of the ring between the blocks ans tightening the clamps. Should give you a better chance of getting it straight than just using a hammer.
OP TobyA 16 May 2014
In reply to wilkesley:

So I went for willesley's g-clamp idea - went to the local huge DIY store but could only find plastic clamps. I was looking at them thinking, hmmm - can they be strong enough? But bought a couple thinking they would come in useful anyway and didn't cost much. Yesterday I took the chain ring off, got some wood blocks, G-clamped it between them and immediately snapped one of the clamps in half getting it moderately tight! Doh.

Plan B involved a hammer and some flat tarmac. That seemed to work quite well, but reattaching the chain ring I could see it was still bent a bit, so tried the adjustable spanner trick - that worked perfectly. Was riding it last night and its was a quiet and purring as an 8 year old mountainbike that is regularly crashed into trees/jumped off from when it goes into ditches/etc. is ever going to be so thanks all!
 Jon Jones 16 May 2014
In reply to TobyA:


I've done the adjustable spanner technique in the past, don't even need to take the ring off the bike.
 Frank4short 16 May 2014
In reply to TobyA:

In my personal experience for chain rings a vice grips is more effective than an adjustable spanner as a) it's not as big a deal if you scratch the shit out of it and b) there's less to grab hold of than a full brake disc. So in keeping with that get a vice grips and use that instead.
OP TobyA 16 May 2014
In reply to Jon Jones:

> I've done the adjustable spanner technique in the past, don't even need to take the ring off the bike.

Yep, it was more easy to do and easier to see once back on the bike!

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