Noisy Drivetrain - New SRAM parts

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jmillen
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Noisy Drivetrain - New SRAM parts

Postby jmillen » Thu Nov 15, 2012 22:52 pm

Evening folks,

I'm having a noise issue and wondered if anyone would be good enough to give their advice.

A bit of background..I have an SRAM Rival medium cage rear mech, 11-32 PG1050 cassette and PC1050 chain. All brand new, fitted this evening. To gauge chain length, I wrapped the chain around the large and large rings, front and back (skipping the rear derailleur).

I've been through and indexed the gears, which appear to be working okay (subject to a little bit more fettling) but what is puzzling me is the constant noise I get in pretty much every gear from what appears to be the rear derailleur, or more specifically, the chain passing through the 2 cogs on the rear derailleur.

I think what is making the noise is the teeth from the cogs are not passing directly into the gaps between the chain links, more hitting the pins, and then sliding into the gap, causing the noise. I guess this could also be a similar thing with the teeth of the cassette.

Have I missed something in the setup, is the chain too slack/too tight? Do I just need to give it a few rides to sort itself out ?

From what I have read so far this evening, alot of the complaints about noises appear to be an issue with the width, but I'm not sure that is the case in this instance. I have read that using a KMC chain may help, which is something I'll maybe look into.

I don't have a huge amount of experience with gearing like this, so any help would be very much appreciated.

Please let me know if you need any more info.

Cheers
James
2010 Specialized Stumpjumper FSR Expert Carbon
2014 De Rosa R848
Carrera TDF Ltd Commuter

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Ed J
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Re: Noisy Drivetrain - New SRAM parts

Postby Ed J » Thu Nov 15, 2012 23:29 pm

I had the exact same problem weirdly enough, until today. Took it to my LBS who said that I'd routed the chain through the rear mech wrong :oops: He took out the jockey wheel, put it how it should be and bob's you uncle, silky smooth

utgaardaolle
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Re: Noisy Drivetrain - New SRAM parts

Postby utgaardaolle » Fri Nov 16, 2012 10:03 am

Done that when fitting a new chain when I was too tired. I was actually dragging the chain over a metal tab by brute force all the way to work the morning after before I could reroute the chain.

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rozzer32
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Re: Noisy Drivetrain - New SRAM parts

Postby rozzer32 » Fri Nov 16, 2012 18:44 pm

Make sure the b screw is adjusted correctly.
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Hairy Boy
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Re: Noisy Drivetrain - New SRAM parts

Postby Hairy Boy » Fri Nov 16, 2012 19:03 pm

I have an non-regular but constant enough noise to be bl*ody annoying tinney sounding chatter from the back end. This is on my recently purchased 2nd hand Giant Giant Defy (shimano gearing)

Having greased the seat/post and wheel dropouts/quick releases and changing the bottom brack, cassette and chain I am coming to the conclusion my noise could be down to the rear wheel spokes not being tightened up properly.

If I grasp the back wheel by the rim and push/pull across its running path I can kind of replicate a similarly tinny noise which appears to be down to spoke/rim movement.

Might be worth checking what appear to be unrelated areas are greased/lubed/tightened before assuming its the rear mech.

Of course it could be the rear mech - as others have said check the chain path is correct through the jockey wheels and b-screw adjustment.

Does the rear mech look straight ? when looking from behind it should broadly look straight up down in most correct combination gears (ie not small ring at the front and small ring at the back)

gloomyandy
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Re: Noisy Drivetrain - New SRAM parts

Postby gloomyandy » Fri Nov 16, 2012 19:24 pm

I think the advice from Sram for chain length is put the chain on Big-Big then add one complete link (so inner and outer plates), plus the joining link. I'd be surprised if having it short caused problems in all of the gears though...

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sungod
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Re: Noisy Drivetrain - New SRAM parts

Postby sungod » Fri Nov 16, 2012 19:40 pm

as above, b screw setting, at least on sram red it makes a big difference to noise and shifting, much more so than with a shimano rear mech

first i'd check the rear hanger is correctly aligned

then, start with b screw set for minimum jockey wheel to sprocket distance (6mm i *think*, but memory could be wrong)

ensure the rear mech is lined up right with the barrel adjuster

then experiment with small increases in distance until you find where noise is least
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jmillen
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Re: Noisy Drivetrain - New SRAM parts

Postby jmillen » Fri Nov 16, 2012 22:37 pm

Thank you for the replies, very much appreciated :)

I'm 995 sure it's a noise coming from the interaction with the rear mech and/or cassette. I have the bike up on the stand so can get in close and watch/listen to where it's coming from.

Discussing it in work today, we actually came to a similar B screw conclusion so I'm going to have a play with it tomorrow, and see how it goes. I'll also check all the alignment and make sure there are no issues there.

Thanks again for the replies, I'll post again with an update tomorrow.

Cheers
James
2010 Specialized Stumpjumper FSR Expert Carbon
2014 De Rosa R848
Carrera TDF Ltd Commuter

philthy3
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Re: Noisy Drivetrain - New SRAM parts

Postby philthy3 » Sat Nov 17, 2012 08:42 am

sungod wrote:as above, b screw setting, at least on sram red it makes a big difference to noise and shifting, much more so than with a shimano rear mech

first i'd check the rear hanger is correctly aligned

then, start with b screw set for minimum jockey wheel to sprocket distance (6mm i *think*, but memory could be wrong)

ensure the rear mech is lined up right with the barrel adjuster

then experiment with small increases in distance until you find where noise is least


That was my first thought.
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gloomyandy
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Re: Noisy Drivetrain - New SRAM parts

Postby gloomyandy » Sat Nov 17, 2012 09:10 am

One other thought (though probably not your problem). Sram rear mechs sem to be much more sensitive to the length of the outer on the last part of the shifter cable. They seem to like a longish cable run with a nice smooth curve. If you get it too short it can cause problems with shifting.


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