What might this be..

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What might this be..

Postby fonts » Mon Sep 24, 2012 1:01 pm

Hi people

I have a weird problem - maybe someone can point me in the right direction.
I have a 2006 Trek 5200 OCLV. I love her.

Anyway recently when riding at higher cadence upfront on the 38T I get what sounds like chain rub on the FD. But it's not - it's clear of the FD in all (non extreme chainline) gears.
Ttrim also doesn't help. It's now just getting really annoying.

Anyone have any clue what it might be ? No noise when running upfront on the 52T.

Chain is about 5 months old - SRAM - with a rear SRAM cassette - always run it pretty clean / good lube etc.

fonts
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by BNA » Mon Sep 24, 2012 11:30 pm

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Re: What might this be..

Postby eeksll » Mon Sep 24, 2012 11:30 pm

probably not quite your issue, if it just started, but I find that when the chain is on a angle there is a bit of what sounds like chain noise but is the chain rubbing on the sides of the chainring teeth due to the extreme angle it has to come off the chain ring.
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Re: What might this be..

Postby Stepr » Tue Sep 25, 2012 8:31 pm

yes I had this issue, though it was rubbing on the front derailer (ans was getting annoying re trying to adjust) but played around with it and worked out it was actually slight touching/rubbing on the side of the large chainring.
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Re: What might this be..

Postby fonts » Wed Sep 26, 2012 7:44 am

ahh - so how did you adjust it away from the large ring enough to not rub ? I had a look at it doesn't appear to be touching - but then again maybe there is just enough flex when it's spinning fast enough to just touch ? I guess thinking about it maybe if there is a very slight bend in either it could contribute to it .. hmm
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Re: What might this be..

Postby eeksll » Wed Sep 26, 2012 4:37 pm

the scenario that I speak of can not be adjusted. except to change gear.

The cassette position is fixed and the chain ring position is fixed. The angle at which the chain comes off the chainring depends on which cassette gear the chain is on. The extreme angle is what causes the noise that I am talking about.

If you have a long chainstay then the angles on all gears should be reduced. But it might be by a insignificant amount.
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