Straightening Mech Hangers, Help Needed.

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dlovett
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Straightening Mech Hangers, Help Needed.

Post by dlovett »

Well the new hanger has arrived so I now have two spare bent hangers.

I have very limited tools and no vice so I was wondering if anybody that did have the tools would fancy having a try to see if they could straighten them for me.

If you could help please drop me a message and I'll post them to you with a return envelope.

I asked the local shop and they didn't want to try, but could order me a new one!

Cheers

d
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psling
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Re: Straightening Mech Hangers, Help Needed.

Post by psling »

I'm guessing that if they are replaceable hangers then they are aluminium? This being the case I would probably bin them; aluminium will weaken under bending and may subsequently fail.
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Zippy
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Re: Straightening Mech Hangers, Help Needed.

Post by Zippy »

I have a blowtorch and a vice I don't mind using. Not promising anything mind, so if I break them, or they break straight away in use - I will not be held accountable!

But yeah, if they're cheaper alu ones, I'd bin them.
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dlovett
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Re: Straightening Mech Hangers, Help Needed.

Post by dlovett »

Zippy wrote:I have a blowtorch and a vice I don't mind using. Not promising anything mind, so if I break them, or they break straight away in use - I will not be held accountable!

But yeah, if they're cheaper alu ones, I'd bin them.
The manufacturer said they should bend straight when I sent them some pictures. I'm happy to take the chance as ideal they will just be emergency back up ones incase I bugger this new one up.

Zippy that would be great, I'll PM you.

Cheers

d
middleagedmadness
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Re: Straightening Mech Hangers, Help Needed.

Post by middleagedmadness »

you should be able to straighten them with just the vice , I tend to find aluminium doesn't respond to well to heat unless your really quick with it , you could try remounting them and tweaking them with a pair of adjustables , worked fine on my old giant (its still on running fine after 6 months)
ScotRoutes
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Re: Straightening Mech Hangers, Help Needed.

Post by ScotRoutes »

You really need to straighten them when fitted to the bike.
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Re: Straightening Mech Hangers, Help Needed.

Post by AlasdairMc »

ScotRoutes wrote:You really need to straighten them when fitted to the bike.
This. Also attach an old rear mech (or just the bolt if you can get it out) so you don't bend the thread at all.
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dlovett
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Re: Straightening Mech Hangers, Help Needed.

Post by dlovett »

ScotRoutes wrote:You really need to straighten them when fitted to the bike.
Doesn't that risk damaging the bike?

I can understand bend in a vice and check on bike, repeat etc, but when attached the to bike.

On the fat bike the shop took it off and ent it in a vice, refitted and repeated etc, but that's a carbon frame so could be different to an ally frame.
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whitestone
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Re: Straightening Mech Hangers, Help Needed.

Post by whitestone »

Ideally you need one of these http://www.chainreactioncycles.com/x-to ... prod122319

I wouldn't have thought that one bending and a straightening would significantly weaken the hanger. Usually you get fatigue when you repeatedly bend a bit of metal back and forth. Then again I'm not a metallurgist.
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ScotRoutes
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Re: Straightening Mech Hangers, Help Needed.

Post by ScotRoutes »

This is the tool used

http://www.chainreactioncycles.com/x-to ... prod122319

Image

It's done with the wheel and mech hanger in situ.

If I was in a bike shop and they didn't have one of those I'd take my bike straight back out again.
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Re: Straightening Mech Hangers, Help Needed.

Post by pistonbroke »

Perhaps I'm being pedantic, wouldn't be the first time.
What you are trying to acheive is a REAR MECH which is in alignment with the cassette, this will not necessarily be achieved by straightening the mech hanger off the bike . You really need to invest in the tool that I and Scotroutes have suggested. There's no guarantee that after 2 knocks, the frame may be slightly out so you may actually need to align the new hanger to the frame.
What I'm hamfistedly trying to say is DO IT YOURSELF. You will learn by your mistakes, theres little chance of knackering your frame as after all that's what the mech hanger is designed to prevent.
padonbike
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Re: Straightening Mech Hangers, Help Needed.

Post by padonbike »

[quote][If I was in a bike shop and they didn't have one of those I'd take my bike straight back out again./quote] :lol: :lol:
Too right!
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dlovett
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Re: Straightening Mech Hangers, Help Needed.

Post by dlovett »

What I meant was wouldn’t using a vice and pliers mean too much pressure, not the mech tool.

The frame is fine the hanger took most of the bang, not sure how the cage got twisted, he6 ho I seem to have found the last me h in the country this side if Jan and it should arrive tomorrow hopefully.
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AlexGold
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Re: Straightening Mech Hangers, Help Needed.

Post by AlexGold »

If you've got a second wheel with a threaded axle, thread it into where the mech would go and use the second wheel as a lever to bend it into line with the one in the bike. It's a hack I use regularly to check mine when servicing it.
middleagedmadness
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Re: Straightening Mech Hangers, Help Needed.

Post by middleagedmadness »

It doesn't take much leverage to bend the mechanic hanger so the frame will be fine ,it didn't damage the frame when it bent so it shouldn't damage it when you straighten it
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Re: Straightening Mech Hangers, Help Needed.

Post by pistonbroke »

I promise you I'm not a mech hanger alignment tool salesman but using anything else, especially pliers or a bodged homemade tool will entail additional unneccesary bending, further weakening the hanger due to metal fatigue. The correct tool shows you in which direction to bend the hanger, screws into the bolt hole preventing damage and just makes the job much easier. At the risk of aquiring a panda, if you'd ordered the one I suggested last week, you would have it by now and have 2 spare usable hangers and the satisfaction of being able to fix your bike rather than just fit new parts to it.
Oli.vert
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Re: Straightening Mech Hangers, Help Needed.

Post by Oli.vert »

:)

With all respect to the above poster, the spare wheel hack will also show you which direction you need to bend the hanger to get it straight. As will looking at the alignment of the upper jockey wheel on the mech itself once mounted though not to anything like the same degree of accuracy. But how accurate do you need? Unsurprisingly the answer is accurate enough for your gears to work properly, but not any more than that.

I should mention though that I AM a mech hanger straightening tool salesman. I probably shouldn't mention that I'm often perfectly happy using a 10" adjustable to do the same job.
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Re: Straightening Mech Hangers, Help Needed.

Post by fatbikephil »

Depends on what the mech hanger is like - if its machined or forged and has a flat surface (they usually do) then it can be bent back using a vice and a suitable spanner which fits snuggly over the bit you are needing to bend. A big hammer and a machined flat surface works too (used with care :mrgreen: ). I'd also aneal it before and after - smear soap on the back, apply blow lamp (or hold over gas stove) gently until soap starts to blacken then remove heat. repeat after bending.
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ctznsmith
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Re: Straightening Mech Hangers, Help Needed.

Post by ctznsmith »

Oli.vert wrote:But how accurate do you need?
I believe Park say within 4mm.

10 speed is (in my experience) randomly more picky regarding a straight hanger than other speed derailleur systems.
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whitestone
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Re: Straightening Mech Hangers, Help Needed.

Post by whitestone »

The 4mm measurement is at the rim not the hanger - https://www.parktool.com/blog/repair-he ... -section-2
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thenorthwind
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Re: Straightening Mech Hangers, Help Needed.

Post by thenorthwind »

If you've got a second wheel with a threaded axle, thread it into where the mech would go and use the second wheel as a lever to bend it into line with the one in the bike. It's a hack I use regularly to check mine when servicing it.
This is the method I use too (I have an old threaded axle I keep for this purpose, with a locknut 10mm or so from the end that I snug up against the hanger to spread the bending force).
The 4mm measurement is at the rim not the hanger
If we're being pedantic, that gives you a different effective error with a different size rim :ugeek:
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ZeroDarkBivi
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Re: Straightening Mech Hangers, Help Needed.

Post by ZeroDarkBivi »

Had to do this manually, for the first time ever, and with only a few minutes to closing time in Lagan Bothy Bikes during this years HT550. No tools, just a work stand and some brute force. Wasn't perfect, but good enough for all 12 gears to work without excessive grinding (after re-tuning another 200km down the road). Normally a bit precious about doing things properly, but when needs must, a bodge can do the trick.
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Re: Straightening Mech Hangers, Help Needed.

Post by ctznsmith »

whitestone wrote:The 4mm measurement is at the rim not the hanger - https://www.parktool.com/blog/repair-he ... -section-2
Yeah probably should have said that. You're supposed to do it on the same point of the rim to allow for the wheel being out of true.

Width of rim doesn't matter as your talking difference against the same point on the same rim.
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