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Weird rear derailleur skipping issue related to chainline?

997 views 8 replies 6 participants last post by  Lombard 
#1 ·
I have a SRAM Red 10-speed setup on my Specialized Roubaix and am encountering some really weird shifting issues with my rear cluster. Both the cluster and chain are just about brand new (Shimano 11-28 Ultegra cassette and KMC 10-speed chain).

I can dial it in just about perfectly for the rear cluster when I am in my big or small ring in front. But when I down/up shift on the front the rear derailleur starts skipping badly in a wide range of gears (especially bad at the higher and lower limits). I tried riding it to see if it was only a bike-stand related issue but its even worse under force.

Any ideas whats going on?
 
#2 ·
If the bike is new then the shifting may need to be adjusted. New bikes cables need to be adjusted some times. Check the rear derailleur to see if the jockey wheels line up with the lowest cog. YouTube has a lot of great videos on derailleur adjustment. There are a lot of super experienced folks are in here to help you. I'm not even close to that level but I'm learning.
 
#3 ·
Its not a new bike (has quite a few thousand of miles on it) and the cables have been replaced at least 3 times that I remember in that lifetime. I can usually deal with cable stretch but this is just weird. Also the alignment on the high/low gears is dead-on as I can get it. It shifts perfectly if I choose either the small or large front gear to adjust it in, its when I shift that front gear that it all goes crazy :p
 
#7 ·
Internal cable routing? If so are the cables wrapped around each other inside the downtube? This happens every now and then. Put the bike in a work stand and very carefully watch the rear derailleur as you pull on the front derailleur cable.
 
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