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Old 01-12-11, 03:31 AM   #1
zohan
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Rear shifter cable slack

Was given an old(er) giant escaper, replaced the cables, housing, cassette (9speed Sram) and chain (9speed Sram).

The problem I am having is the rear shifter cable is totally slack in the smallest cog. If there is any tension at all on the cable then the chain does not ride properly on any of the other cogs as if there is too much cable tension.

Here is what i have done to troubleshoot this:
1. I have aligned the derailleur hanger (park dag-2).
2. I have ensured the hanger is tight to the frame.
3. I have completely cleaned and lubed the derailleur.
4. I have uninstalled and reinstalled the cassette. Torquing the lockring down to the specification listed on the lockring.
5. I have double checked the high limit screw.
6. I have ensured the cables and housing are seated properly in the frame and that the housing is not too long or too short, (sized them according to th Barnetts maintenance manual).
7. I have checked to make sure the hub is properly seated in the rear dropouts.
8. I have checked the chain is the proper length (per barnetts manual as well).
9. I have also checked that the cable goes in the correct direction from the adjusting barrel to the anchor bolt.

Shifting is ok up and down the cassette but there is no tension on the cable in the smallest cog. When I snug the cable even slightly then there is too much tension for the rest of the cogs and shifting down to each smaller cog is affected.

This is a shimano LX rear derailleur, 9 speed rapidfire shifters.

I am at a loss of what else to do to trouble shoot this. The cable shouldn't just be flopping on the top tube.

Anyone have a clue?

Last edited by zohan; 01-12-11 at 03:34 AM.
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Old 01-12-11, 07:46 AM   #2
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Zohan: If the shifting is OK, what problem are you trying to solve? I don't see how a slack cable is going to do any harm.
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Old 01-12-11, 07:58 AM   #3
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sounds good to me.
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Old 01-12-11, 10:08 AM   #4
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It's normal for the RD cable to be slack in high gear, so you'll never be able to troubleshoot a solution.

As you already know the RD cable tension has to be set for best indexing on all the sprockets except the smallest, where the RD rests on the limit screw. You could back away the limit allowing the RD to move out and take up some of the slack, but that would mess up the trim in high.

Most systems have extra space between the high and 2nd clicks in levers. They do it for a variety of reasons from making the assembly of shifters easier, to making it easier to pull up slack when attaching the RD cable.
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Old 01-12-11, 11:09 AM   #5
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Originally Posted by FBinNY View Post
It's normal for the RD cable to be slack in high gear, so you'll never be able to troubleshoot a solution.

As you already know the RD cable tension has to be set for best indexing on all the sprockets except the smallest, where the RD rests on the limit screw. You could back away the limit allowing the RD to move out and take up some of the slack, but that would mess up the trim in high.

Most systems have extra space between the high and 2nd clicks in levers. They do it for a variety of reasons from making the assembly of shifters easier, to making it easier to pull up slack when attaching the RD cable.
I have never seen a setup where the cable was so slack the cable justs sits slap happy against the frame with zero tension on it.

I understand the functionality of ensuring the indexing is good in all the other gears and that the system shifts down to the smallest cog but shouldn't there be at least some tension on the cable?

Right now there is none.
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Old 01-12-11, 11:20 AM   #6
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Quote:
Originally Posted by zohan View Post
I have never seen a setup where the cable was so slack the cable just sits slap happy against the frame with zero tension on it.

I understand the functionality of ensuring the indexing is good in all the other gears and that the system shifts down to the smallest cog but shouldn't there be at least some tension on the cable?

Right now there is none.
Systems vary, and totally slack in high isn't all that rare. I can't see your bike, so don't know how slack is slack but it seems OK and normal to me.

You know the tension is OK because the RD indexes and trims correctly, you know the high limit is OK because the trim in high is OK, so what is, is and you should ride it instead of obsessing over a non-problem.

If it really bothers you, you might try backing the high limit as far as you can while still maintaining decent trim in high. Other than that you're probably seeing the result of a free running unkinked wire, so all the slack shows.

If you're skilled and it really is that important to you you might be able to improvise a bump stop in the shifter (easier with some than others) so the cam doesn't rotate as far in high, but I wouldn't bother.
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Old 01-12-11, 11:48 AM   #7
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Edit: I didn't publish my post until awhile after I wrote it, FB had already said what I had, and more.
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Old 01-13-11, 07:34 AM   #8
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+1 FB again
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