Breaking rear mechs...
 

[Closed] Breaking rear mechs- WTF is going on? ARGH

 hora
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So I had my XTR rear mech on EVERY bike (theres been a few) from 2002-two weeks ago. Then it finally (I thought) gave up.

I replaced it with a new SLX rear mech. Last Sat the rear mech AND the mech hanger sheared off thankfully not taking the spokes with it.

Last night I discovered the latest (new) rear mech is bent.

What is happening? Could it be a rear triangle out of line? (Orange Patriot frame).

Its got a new hanger on, all is tight/cant feel any play BUT there was tiny bit of horizontal play in the offset bush in the bottom of the air shock.

Cant be this?! Rear mechs are expensive these days. I'd rather not be buying new ones every two weeks ๐Ÿ˜ฏ


 
Posted : 07/05/2014 11:11 am
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chain too short?


 
Posted : 07/05/2014 11:12 am
 hora
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In the biggest setting (1x9) setup the mech sits horizontal- not pulled forward.


 
Posted : 07/05/2014 11:14 am
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is that with the suspension fully compressed?

(ie all air out the shock)


 
Posted : 07/05/2014 11:15 am
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I've had a very similar issue and gone through 4 mech hangers in 3 weeks. The only way forward to is to list everything it could be and elimate them one by one. I think my mech cage was slightly bent causing the line on the tension jockey to be off causing the chain to get caught between the jockey and cage. It could also be a stickey cable (muck in the outer?) causing the mech to drag on the change, I put the power on to get up a hill say and then it changes and again crossed line on the jockey.
If you've elimnated everything else then it can only be the frame.


 
Posted : 07/05/2014 11:18 am
 hora
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wwaswas Will check. The only other change I've done recently is gone from a 216-63(?) to a 200*57 shock

jekkyl- I reused the outer and end-gromit as I was too lazy to rethread through the swingarm again. Will refresh this though (the inner is brand new).


 
Posted : 07/05/2014 11:18 am
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Mark, a mate had the same thing on his Patriot when we were out in the Alps. He'd changed the shock shuttle to put it in the slackest setting and destroyed 2 mechs on the first day. Lengthened the chain by a few links and sorted it... Might be that the old XTR was pulled forward easily due to a worn spring vs the newer crop of mechs which resist a bit more resulting in mech damage...


 
Posted : 07/05/2014 11:21 am
 hora
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Got it- that sound exact as mine/with my changes I've made too- will lengthen the chain by a few links ta ๐Ÿ™‚


 
Posted : 07/05/2014 11:26 am
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[i]The only other change I've done recently is gone from a 216-63(?) to a 200*57 shock[/i]

I'd say the suspension is compressing a bit more than it used (even though overall travel is likely to be the same or less) - look at adding a couple of links.


 
Posted : 07/05/2014 11:27 am
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your new shock is 143mm fully compressed and old shock was 153mm so sitting far further into it's travel, patriots have a fair bit of chain growth so you're on the right track with an extra link or two. only way to be sure is to check chain at full compression with spring off or all the air out


 
Posted : 07/05/2014 11:36 am
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Yep, sounds like the chains too short.
Put in first, dump the air out of the shock and compress.


 
Posted : 07/05/2014 11:41 am
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it could only happen to you Hora... ๐Ÿ˜‰

if you need a rear mech i have a Deore 9sp (long cage) going spare...


 
Posted : 07/05/2014 12:03 pm
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I think you need a new bike.


 
Posted : 07/05/2014 3:36 pm
 hora
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I'm waiting on a LT2, Blur TR or Blur 4X to pop up..


 
Posted : 07/05/2014 3:41 pm
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This happened to me with a brand new x0 mech. Chain too short.100%


 
Posted : 07/05/2014 3:58 pm