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rear derailleur cable/shifting help

MMcG

Ride till you puke!
Dec 10, 2002
15,457
12
Burlington, Connecticut
Here's the scoop

Over the last couple of rides I've been having trouble shifting my bike from the middle ring/biggest cog setting down if you will into the smaller cogs.

I'm thinking my cable may be too slack for the bike to shift into the smaller cogs - but I suck at these types of adjustments.

Can anyone give me the rundown or step by step process to try and address this issue? And if possible please keep it as simple as possible.

Btw, I run an older SRAM 9.0 rear derailleur with SRAM 9.0 grip shifters.

Thanks in advance for any help you can provide
 

sanjuro

Tube Smuggler
Sep 13, 2004
17,373
0
SF
Could be the length of your housing from the stay to the rear derailleur. The bend of this housing could affect this.

If you could take a picture...
 

nycurse

Monkey
Jul 27, 2006
296
0
yea a pic would help alot. also it may be that your front and rear are not adjust fine enough so it can shift into the middle while its on lower cogs
 

MMcG

Ride till you puke!
Dec 10, 2002
15,457
12
Burlington, Connecticut
this just happened during the last two rides. Also I run two rings and a bashguard - no big chainring.

I think it is just a matter of cable tension. I'll see if I can get it working properly tonight. I need to learn sometime right?
 

punkassean

Turbo Monkey
Feb 3, 2002
4,561
0
SC, CA
How old and what type of cable/housing are you running?

I only use top-shelf cable/housing as it performs so much better and lasts longer. Also I have had much better luck with 5mm housing than the wimpy 4mm crap.
 

punkassean

Turbo Monkey
Feb 3, 2002
4,561
0
SC, CA
MMcG said:
I can't remember but it is decent stuff. Less than a year old.
1-year old can be a lot depending on conditions/mileage. If you can't get it dialed pretty quick here I'd re-cable it and see if that does it. Do you run 4mm or 5mm housing? Also the slick XTR cable works very well, especially on front derail's because of their strong spring tension.
 

MMcG

Ride till you puke!
Dec 10, 2002
15,457
12
Burlington, Connecticut
I tried to follow the park tool directions last night....I've got things shifting pretty well now. Not 100 percent, but pretty decent. Now if I can only remember what I actually did - lol - it was mostly a bunch of trial and error - no real method to my madness, but I've got more than just two gears now, so that's a step in the right direction.
 
Feb 13, 2006
299
0
MMcG said:
Here's the scoop

Over the last couple of rides I've been having trouble shifting my bike from the middle ring/biggest cog setting down if you will into the smaller cogs.
If I understand you correctly, you are having trouble getting the rear der to move outboard from the 34t down the stack to the 11 or 12t smallest cog.

If that's the case, too much cable tension will prevent it from moving down the stack.

Too little cable tension and you won't be able to move back up the stack.

The trick is to get it slack enough to move down the stack, but taut enough to move back up the stack.

I would suggest running the grip shift twister all the way out to the setting for cog 9. then loosen the anchor for the cable on the rear der. let it get slack, pull it free from where it was anchored.

now make sure your rear der is lined up over the smallest cog, so that you're sure the der is travelling all the way to the end of the stack.

okay, with the chain on the middle ring (in your 2-ring setup, the big ring) up front, and on the smallest cog in the rear, and the grip shifter set at 9, now run your barrel adjuster on the grip shifter all the way IN, and then back it out ONE FULL TURN.

now grab the rear der free end of the rear der shift cable and pull it somewhat tight with a pair of pliers, and re-tighten the anchor bolt.

now shift it all the way back up the stack to the 34t big cog. grip shifter should be on 1 now. if it doesn't make it all the way up, turn the barrel adjuster on the grip shifter OUT until it has enough tension in the cable to make the chain travel to the 34t.

now start back down the stack, running the grip shifter from 1 to 2, then 2 to 3, etc. whenever the chain refuses to go down to the next smallest cog, turn the barrel adjuster on the grip shifter IN until the chain will move downward.

keep repeating the up-the-stack and down-the-stack tests and barrel adjustments until it will work in both directions all 9 cogs.

All the above stuff assumes your cable isn't binding within the housing. You may want to lube the cable if it doesn't feel like it shifts smoothly after trying the above steps.
 

oldfart

Turbo Monkey
Jul 5, 2001
1,206
24
North Van
Generaly speaking, if the bike shifted well at one point, and there is no visible damage to anything, it is simply a fouled cable and housing. When i raced a lot and was riding 10 to 20 hours a week off road, I would be changing the cable and housing once a month. Absolute age is irrelevant. Derailleurs and cables don't go out of adjustment if they are set up right to begin with. Once the cable is tightened you grab an open section of the cable and pull hard. That will seat it all in place and after that you retighten and adjust. There is no reason for thew system to come out of adjustment after that. If it won't drop into a smaller sized cog, tha cable is probably dirty and sticky and not allowing the shift to happen. Some people will loosen the cable a bit to allow it to actually shift OK, but then the shift to the lower gears or larger sized ones requires a bit more overshift. People tend to think that their cable has come out of adjustment when in fact it's just dirty.
 

Wumpus

makes avatars better
Dec 25, 2003
8,161
153
Six Shooter Junction
oldfart said:
Once the cable is tightened you grab an open section of the cable and pull hard. That will seat it all in place and after that you retighten and adjust. There is no reason for the system to come out of adjustment after that.
While that is mostly true, the plastic sheath on the derailer housing will compress some over time and the cable strands will poke out of the ends of the housing. These flex a little and can cause minor shifting problems.
 

MMcG

Ride till you puke!
Dec 10, 2002
15,457
12
Burlington, Connecticut
particle bored said:
If I understand you correctly, you are having trouble getting the rear der to move outboard from the 34t down the stack to the 11 or 12t smallest cog.

If that's the case, too much cable tension will prevent it from moving down the stack.

Too little cable tension and you won't be able to move back up the stack.

The trick is to get it slack enough to move down the stack, but taut enough to move back up the stack.

I would suggest running the grip shift twister all the way out to the setting for cog 9. then loosen the anchor for the cable on the rear der. let it get slack, pull it free from where it was anchored.

now make sure your rear der is lined up over the smallest cog, so that you're sure the der is travelling all the way to the end of the stack.

okay, with the chain on the middle ring (in your 2-ring setup, the big ring) up front, and on the smallest cog in the rear, and the grip shifter set at 9, now run your barrel adjuster on the grip shifter all the way IN, and then back it out ONE FULL TURN.

now grab the rear der free end of the rear der shift cable and pull it somewhat tight with a pair of pliers, and re-tighten the anchor bolt.

now shift it all the way back up the stack to the 34t big cog. grip shifter should be on 1 now. if it doesn't make it all the way up, turn the barrel adjuster on the grip shifter OUT until it has enough tension in the cable to make the chain travel to the 34t.

now start back down the stack, running the grip shifter from 1 to 2, then 2 to 3, etc. whenever the chain refuses to go down to the next smallest cog, turn the barrel adjuster on the grip shifter IN until the chain will move downward.

keep repeating the up-the-stack and down-the-stack tests and barrel adjustments until it will work in both directions all 9 cogs.

All the above stuff assumes your cable isn't binding within the housing. You may want to lube the cable if it doesn't feel like it shifts smoothly after trying the above steps.
Thanks for this post. I've saved it for reference!