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Campagnolo Chorus 12s upper pulley adjustment problem

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Campagnolo Chorus 12s upper pulley adjustment problem

Old 12-01-21, 12:36 PM
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Panos4
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Campagnolo Chorus 12s upper pulley adjustment problem

Hi
Im using campagnolo Chorus 12s last 2 years with no problems at all. (32-48 with 11-34)
Suddenly the upper pulley of rear mech started touching the 34 cog badly. I screwed in the small screw so much, until it was almost out to go back home.
I changed the wire and re adjusted But nothing changed.
Has anybody experienced simething like that?
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Old 12-01-21, 10:54 PM
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Andrew R Stewart 
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The two sprung pivot slant parallelogram ders allow for real nice guide pulley to cog lower side gap assuming a few things. Cog size and der's capacity being first. Chain length next. Having a certain "balance" of the two pivots' spring tensions and their free movement, and the pulleys also freely spinning.

The problem I have with trying to address a problem long distance is that I have to rely (so far with no other photos or data) on what is said and you used the word "suddenly". Suddenly suggests an incident. A change that happened in a very short timeline. The usual wear, tear and exposure issues (grit and corrosion) don't tend to happen "suddenly". So that reference suggests some other thing is the cause. So why saying this do I think otherwise?

Because I have helped so many riders who look at a problem as starting on day 10 when the root of it started on day 1. They just didn't feel the growing issue till it crossed their personal threshold of awareness.

It is possible that some part of the der broke? sure but very un common without other aspects going on. I suggest that the complete drivetrain be serviced, cleaned and lubed, base lined WRT it's adjustments and during the cleaning the feel of pivots motions are looked into.

And also check the pulley pivots. A sticky pulley can cause the cage to play in and out. Andy
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Old 12-02-21, 10:07 AM
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Panos4
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Thank you Andy
All part of transmission are cleaned, lubricatad and adjusted thoroughly.
I observed a small play at the junction between the main der and the extention by which the derailleur is attached to the hanger.
Ill try to open that junction.
But first I'll get a new derailleur for replacement and comparison.
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Old 12-02-21, 12:35 PM
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Originally Posted by Panos4 View Post
Thank you Andy
All part of transmission are cleaned, lubricatad and adjusted thoroughly.
I observed a small play at the junction between the main der and the extention by which the derailleur is attached to the hanger.
Ill try to open that junction.

But first I'll get a new derailleur for replacement and comparison.
You didn't happen to tighten the pivot bolt in an attempt to reduce the play? The derailleur needs to rotate freely on both pivot. I find it is fairly common to see a little play in the upper pivot on Campag derailleurs when they are installed correctly. If the upper pivot is too tight the derailleur will not move properly and could cause the issue you are seeing.
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