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Old 03-30-07, 08:00 PM   #1
Big R
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Shifting issue

Sooo...

I just changed my bike from indoor to outdoor. During the winter I use a different chain/cassette combo (to save wear/tear, and cuz those Spinervals are so damn hard anyway) on my trainer.

In going back to my outdoor combo, I'm running a 12-23 cassette and the chain keeps skipping right on over the 13. Otherwise, my shifting is silky smoothe...just won't stay on the 13 (lg chain ring).

I was having no problems in the fall before I took the cassette/chain off...very strange. How could it seem properly adjusted in the 12, 14, 15, etc. but totally **** on the 13? I can't see any obvious signs of distress on the cog, and it's not on backward (I double-checked)...plus I was having no problems before I took it off.

Cassette was stored carefully in tool box during the winter.

Any ideas?

Many thanks

Last edited by Big R; 03-31-07 at 05:05 AM.
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Old 03-30-07, 08:06 PM   #2
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Spacers?
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Old 03-30-07, 08:09 PM   #3
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Actually, since it is skipping the 2nd cog, it's more likely a cable tension issue. You'll need to readjust the RD from scratch (Campy baseline is 4th cog - not sure Shimano), or your RD/hanger is not quite lined up straight any more.
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Old 03-31-07, 05:08 AM   #4
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spacers are fine

tension...I've thought about it tons....I completely re-adjusted the RD yesterday as well. In setting the L limit screw, I loosened the barrell adjuster so it was just a little slack, then set the L screw by tightening the cable with my hand rather than the shifter (per the excellent instructions from the Park web-site). It was doing the same thing then...I hoped the problem would go away when I re-tightened the cable and started using the shifters...no luck.
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Old 03-31-07, 05:25 AM   #5
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It sounds like you have probably checked the obvious, but I know someone once who assembled the cogs in the wrong order.
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Old 03-31-07, 05:59 AM   #6
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Quote:
Originally Posted by Big R
...then set the L screw by tightening the cable with my hand rather than the shifter...
The cable tension has absolutely nothing to do with the L screw (low limit adjustment) or the high limit for that matter. Those screws simply establish the limit of the derailer's overall travel and have nothing to do with your problem, except maybe your high limit was not adjusted properly before the cable was attached, which would present indexing issues.

Shift to the small (12) cog. Remove the cable from the derailer. Turn in your barrell adjusters. Adjust the H limit screw so the chain is lined up with the small cog, check for smooth operation by turning the cranks and making sure the chain doesn't catch on the next cog. Double check the shifter to make sure it's in the high/normal position, to match the derailer's position. Now re-attach the cable. Check the shifting and tweak the cable tension as needed with the barrel adjuster. Now shift to the largest cog, if it won't go then loosen the L limit screw a bit. Once the chain is on the large cog, tug the cable by hand and ensure that the limit is keeping the derailer from traveling past the cog and into the spokes, adjust the L limit as necessary.
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Old 03-31-07, 06:08 AM   #7
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Sorry, in my previous post I meant the "H" limit, not the "L" limit...and I understand the relationship between cable tension and limit screws.

What I don't understand is why the limits are working fine, my 12 and 14 cogs are working fine and smoothe, but the chain won't stay in the 13....change cable tension either way doesn't seem to affect the issue.
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Old 03-31-07, 06:10 AM   #8
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... but I know someone once who assembled the cogs in the wrong order.
Certainly not beyond the realm of possibility...but not the case this go 'round.
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Old 03-31-07, 06:36 AM   #9
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Quote:
Originally Posted by Big R
Sorry, in my previous post I meant the "H" limit, not the "L" limit...and I understand the relationship between cable tension and limit screws.

What I don't understand is why the limits are working fine, my 12 and 14 cogs are working fine and smoothe, but the chain won't stay in the 13....change cable tension either way doesn't seem to affect the issue.
Maybe a bent derailer hanger?
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Old 03-31-07, 07:24 AM   #10
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Does the chain skip over the 13 when going from the 12 to the 14, or from the 14 to the 12?
If the first case then too much tension, in the second case too little tension or dirty cable housing.

Try lubricating the cable through the short housing just before the derailleur. If you loosen the cable you can slide the short housing up the cable exposing the cable for lubrication.

Are you able to shift to all other cogs?

Is the cable routed correctly at the derailleur pinch bolt?

Al
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Old 04-01-07, 01:49 PM   #11
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Quote:
Originally Posted by Al1943
Does the chain skip over the 13 when going from the 12 to the 14, or from the 14 to the 12?
If the first case then too much tension, in the second case too little tension or dirty cable housing.

Try lubricating the cable through the short housing just before the derailleur. If you loosen the cable you can slide the short housing up the cable exposing the cable for lubrication.

Are you able to shift to all other cogs?

Is the cable routed correctly at the derailleur pinch bolt?

Al
1. Both ways...
2. Haven't lubed cable...will try
3. Yes
4. Yes
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Old 04-01-07, 01:53 PM   #12
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question 5: Have you checked your RD/ hanger to make sure it's still straight and aligned?
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Old 04-01-07, 07:29 PM   #13
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Quote:
Originally Posted by vpiuva
question 5: Have you checked your RD/ hanger to make sure it's still straight and aligned?
no...but I'll do that first thing in the a.m.

tHX
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