Rear dérailleur, or something else?

adamr
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Rear dérailleur, or something else?

Postby adamr » Sun Apr 28, 2013 3:51 pm

I noticed today a 'buzzing' feeling when in the higher half of the cassette and small front chainring. More a feeling through the pedals than a sound. I am not sure what it is, but wonder if it is a slight derailleur misalignment with the cassette cogs, meaning the chain is rubbing on the jockey wheels. Indexing is fine, as the changes are crisp, but the feeling is not quite right. Has anyone else experienced this?

I did not notice it in the big ring, small cog combinations, but I don't use those anywhere near as frequently, so I may have missed it.

ironhanglider
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Re: Rear dérailleur, or something else?

Postby ironhanglider » Sun Apr 28, 2013 4:00 pm

Rubbing on the outer plate of the front derailler?

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Cameron
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adamr
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Re: Rear dérailleur, or something else?

Postby adamr » Sun Apr 28, 2013 8:51 pm

ironhanglider wrote:Rubbing on the outer plate of the front derailler?

Thanks Cameron, but it is not a metallic sound. I do get that rubbing with extreme cross-chaining, but it is a distinct sound.

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jules21
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Re: Rear dérailleur, or something else?

Postby jules21 » Mon Apr 29, 2013 9:32 am

when you say the "higher half of the cassette", do you mean the higher ratio half, or the higher (as in height of the cogs) half?

adamr
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Re: Rear dérailleur, or something else?

Postby adamr » Mon Apr 29, 2013 11:08 am

jules21 wrote:when you say the "higher half of the cassette", do you mean the higher ratio half, or the higher (as in height of the cogs) half?


Higher (harder) gears, that is, smaller cogs.

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jules21
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Re: Rear dérailleur, or something else?

Postby jules21 » Mon Apr 29, 2013 11:17 am

it could be chain rubbing on the big chainring, which would be caused by bad chainline (incorrect fitment of spacers in BB bearing cup, assuming you're using a HT BB).

adamr
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Re: Rear dérailleur, or something else?

Postby adamr » Mon Apr 29, 2013 3:18 pm

I am using external bearings, but they are Rotor ones. How would I go about diagnosing whether that is the problem?

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jules21
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Re: Rear dérailleur, or something else?

Postby jules21 » Mon Apr 29, 2013 3:29 pm

adamr wrote:I am using external bearings, but they are Rotor ones. How would I go about diagnosing whether that is the problem?

the potential problem I cited was the chain rubbing against the big chainring. that has nothing to do with the BB bearings - you can observe whether that's occurring or not. but if it is happening, spacing out the drive-side BB bearing may be the solution. (they usually come with spacers that sit in between the BB bearing and shell faces)

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twizzle
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Re: Rear dérailleur, or something else?

Postby twizzle » Tue Apr 30, 2013 9:28 am

:roll:

Don't cross-chain.
I ride, therefore I am.
...real cyclists don't have squeaky chains...

adamr
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Re: Rear dérailleur, or something else?

Postby adamr » Tue Apr 30, 2013 3:50 pm

twizzle wrote::roll:

Don't cross-chain.


I am not talking about cross-chaining as usually understood (extreme combinations). Just small front ring and past centre of the cassette. That is why I am confident it is not front derailleur rub, because I know that happens when cross-chaining and I avoid it.

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singlespeedscott
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Re: Rear dérailleur, or something else?

Postby singlespeedscott » Tue Apr 30, 2013 7:44 pm

Could be a B tension screw adjustment. Have you recently changed cassette ratio's. If so maybe the upper jockey wheel is now rubbing on the cassette giving you the feed back through the pedals.
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adamr
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Re: Rear dérailleur, or something else?

Postby adamr » Wed May 01, 2013 6:27 pm

singlespeedscott wrote:Could be a B tension screw adjustment. Have you recently changed cassette ratio's. If so maybe the upper jockey wheel is now rubbing on the cassette giving you the feed back through the pedals.


No, but I did change the cassette to new wheels, and I changed the gear cable. Accordingly, I have adjusted the derailleur recently. I will check the B tension screw. Good suggestion, thanks.

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