Rear Der. Adjustment Question

[David Loving]

I changed a 10 speed cassette to a 13-29. Bike has a Chorus alloy medium rear derailleur. New chain. No matter how I adjust the der. I get slipping at some point. Now it's at 3rd from largest cog. Shift to that cog and it wants to move off down to the next lowest cog. Anyone know how to adjust it ?

[nova_rider]

I'd first verify rd hanger & wheel alignment, next shift to the fourth smallest cassette/big gear front, finally lineup/center the rd pulleys/chain using the barrel adjuster, that should do it.

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[bikerjulio]

I'd agree that hanger alignment is the #1 guess.

after that, check height and adjust if necessary.

are the upper and lower pulleys in the correct locations?


ps. The Chorus RD is presumably fairly old, so there is it's general state of wear to consider also. Main pivot bushing worn? You don't need a medium cage RD for that gearing. A short cage will be fine.

[David Loving]

Thanks for the advice. I'm going to keep adjusting until I get to something I can live with.

[nova_rider]

Is this a new cassette? One other thing to point out is be mindful of the cable tension as related to the shift activation. On my old 10 spd Record RD, I notice a difference with as little as 1/2 turn of the barrel adjuster when things are dialed-in, not enough to cause any rub, but can make a difference.

Often times it is easier just to reset everything... undo the cable at the RD, reset the shifter, preset the barrel to about 2/3 the way in, hand tension/tighten the cable, the perform the 4th cog alignment via barrel adjustment.

Good luck!

[David Loving]

Cable tension is the only thing I haven't tried. The turns of the barrel adjuster just moves the unstable cog to a different place on the casette.

[bikerjulio]

Cable tension is the only thing I haven't tried. The turns of the barrel adjuster just moves the unstable cog to a different place on the casette.

Cable tension is changed with the barrel adjuster. And as NOva says even 1/4 turn can make a difference.

What about all the other things that have been suggested?

Hanger alignment?

Height?

Age and use of RD?

Pulleys in the right place?

Plus another one.

What shifter are you using? How old and used is it? With the pre-2009 g-spring shifters, as the springs and carrier wore, shifting quality would drop off. Even if everything else was perfect you could still get crappy shifting with a worn shifter.

[Keezx]

-Spacers in the correct order?
-Cable mounted in the correct way (correct side of the bolt?

[David Loving]

Everything about, and on, the bike is old. I found a way to check the 4th sprocket alignment is perfect using a right angle metal rule. Tightened the shifter cable, and finessed the shifting using the barrel adjuster. It now works. Again, thank you forumites for the excellent advice. I think tightening the shift cable was the fix.