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Old 01-07-08, 08:17 PM   #1
brians647
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poor shifting rear derailleur - argh!

Okay, I've tried everything to get my rear derailleur to shift properly, and nothing is helping. It's a DA 10 speed short cage, running a 12-27 cassette on a Mavic wheel. I have an identical setup on another bike, and it shifts like butter. I've asked a lot of people about it, and before I take it back to my LBS tomorrow, I wanted to put the problem out there.

The behavior is not consistent. Sometimes it wants to shift up more than one gear, and then it won't want to shift down until you've tapped the mech 2 or 3 times. So it seems tight, right? Then you loosen it, and it still shifts goofy! It'll grab gears erratically, it won't shift down cleanly, everything ends in a "clunk." Maybe you'll get 10 clean shifts, then 5 crappy ones. It's driving me nuts!

So, here's what I've done.

Replaced both housings, front and rear - there was little to no binding before or after the replacement whatsoever.

Checked the rear spring - it's not sticking, it returns fine.

Rethreaded the cable and retensioned it about 5 times to no avail.

Swapped wheels/cassettes - still did it.

Chain is fine.

Took it to LBS - he found the rear derailleur cage to be out of whack - straightened it and it's as bad or worse.

Note: before the LBS straightened the cage (and I trust this guy, he knows his stuff) the shifting problem seemed to occur later in my ride - that seems to be when I would shift into the big ring. Using the big ring seemed to bring the problem on.

Now it just shifts poorly in both rings.

Any suggestions? I've been chasing this for weeks. Thanks in advance!
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Old 01-07-08, 08:23 PM   #2
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cracked chainstay?
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Old 01-07-08, 08:46 PM   #3
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cracked chainstay?
Nah.. I've had it apart 18 times and would've seen that. Thanks though.
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Old 01-07-08, 08:50 PM   #4
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are you sure that you have the spacer behind the cassette? I forgot it once and had almost the same probs a you, it took me a while to figure it out.
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Old 01-07-08, 09:10 PM   #5
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Did the LBS check the alignment of the derailleur hanger? If it is bent it won't shift right no matter what you do. Even if it looks ok to the naked eye it could still be out of alignment.
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Old 01-07-08, 09:12 PM   #6
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Why was the cage out of whack? Did you take a spill or did the derailluer get hit or damaged some other way? If the derailluer cage was bent I would bet that the hanger is bent as well.
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Old 01-07-08, 09:19 PM   #7
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are you sure that you have the spacer behind the cassette? I forgot it once and had almost the same probs a you, it took me a while to figure it out.
Yep, both spacers are there.

Cannondaler "Did the LBS check the alignment of the derailleur hanger? If it is bent it won't shift right no matter what you do. Even if it looks ok to the naked eye it could still be out of alignment."

I'm not sure what the issue was, but the bike was never crashed. It did this from the time it was new. He checked both components and aligned both as they should be. I have access to all 10 gears, just not cleanly.
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Old 01-07-08, 09:30 PM   #8
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The only things left to try are
1. you said you replaced the housing, did you replace the cable? If not I would go ahead and do that just to be sure.
2. You swapped wheels. Did you try the wheel from this bike on the other bike and make sure it works there? I would do this just to be absolutely sure it isn't a cassette issue.
3. You said the chain is fine. Did the LBS put a wear gauge on it? They probably did but if not have them check it.
4. If your pretty sure it isn't a bent hanger then the only thing left is the shifter. It is possible to get a bad shifter even on a new bike although it is rare.
5. If the LBS said the derailluer was bent then it is suspect. Even if they bent it back it doesn't mean it is working properly. If they can have them swap it and test another one before you move to replacing a shifter.
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Old 01-07-08, 09:36 PM   #9
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The only things left to try are
1. you said you replaced the housing, did you replace the cable? If not I would go ahead and do that just to be sure.
2. You swapped wheels. Did you try the wheel from this bike on the other bike and make sure it works there? I would do this just to be absolutely sure it isn't a cassette issue.
3. You said the chain is fine. Did the LBS put a wear gauge on it? They probably did but if not have them check it.
4. If your pretty sure it isn't a bent hanger then the only thing left is the shifter. It is possible to get a bad shifter even on a new bike although it is rare.
First off, thanks for the helpful posts - much appreciated.

No, I didn't replace the cable, although I've contemplated it. It's kink/bend free, and it would seem to be superfluous to do so.

2&3 I did. And the wheel/cassette worked perfectly.

Lastly, is the shifter. I've contemplated getting another just to try it out. I'm trying to figure out how to do it so I'm reliably testing the shifter, without having to undo the brake cables, and all that and mounting it up - but that's another story...

Again, thanks for your help!
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Old 01-07-08, 09:36 PM   #10
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Yep, both spacers are there.

Cannondaler "Did the LBS check the alignment of the derailleur hanger? If it is bent it won't shift right no matter what you do. Even if it looks ok to the naked eye it could still be out of alignment."

I'm not sure what the issue was, but the bike was never crashed. It did this from the time it was new. He checked both components and aligned both as they should be. I have access to all 10 gears, just not cleanly.
If the hanger is bent you would have access to all ten gears but not cleanly. Ask the mechanic if he used an alignment gauge on the hanger. Ten speed rear ends are very touchy and if the hanger is even a little off it won't shift cleanly.
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Old 01-07-08, 09:38 PM   #11
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Good luck!
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Old 01-07-08, 09:41 PM   #12
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You could get another shifter and wire a new piece of housing from it to the front cable stop and just mount it on a broom handle to test the shifting without taking the original off the bike.
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Old 01-07-08, 09:48 PM   #13
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Good luck!
I think this quote about sums it up!

But seriously, I believe he used a gauge for the derailleur, I'll ask to be sure. And I can see how touchy it would be. The broom stick idea should work too, as it's the housing that provides the indexing accuracy, not the shifter mount (so to speak).

Anyway, I'll post back if a solution is found. Great advice. Thanks much!
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Old 01-07-08, 10:45 PM   #14
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Are you sure the cable is routed and attached to the derailleur correctly? Compare the routing and attachment to the one that shifts well. The attachment is critical.

Al
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Old 01-07-08, 11:13 PM   #15
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Are you sure the cable is routed and attached to the derailleur correctly? Compare the routing and attachment to the one that shifts well. The attachment is critical.

Al
Great suggestion. And, yes, originally I had it screwed up (twice, in fact!). However, now, it is wired correctly. The LBS confirmed that (he's the one who caught my first mistake).

Thanks Al.
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Old 01-07-08, 11:19 PM   #16
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Hmm, I would tend to say that there is a kink in the cable, but you said you ruled that out, so I have no other suggestions other than what others have suggested. When you go to the lbs again, have him drop in a new cable just to be sure.
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Old 01-07-08, 11:22 PM   #17
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If the hanger is bent you would have access to all ten gears but not cleanly. Ask the mechanic if he used an alignment gauge on the hanger. Ten speed rear ends are very touchy and if the hanger is even a little off it won't shift cleanly.
This has been my experience as well. It wasn't until I got a Park DAG-1 and very carefully aligned the hanger to the wheel that I could get perfect, clean rear shifts on one of my bikes. It was off by far less than the Park web site seems to suggest is an acceptable tolerance.
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Old 01-07-08, 11:34 PM   #18
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Hmm, I would tend to say that there is a kink in the cable, but you said you ruled that out, so I have no other suggestions other than what others have suggested. When you go to the lbs again, have him drop in a new cable just to be sure.
Thanks Matt. As I'm almost out of options, I will probably have to do that.

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This has been my experience as well. It wasn't until I got a Park DAG-1 and very carefully aligned the hanger to the wheel that I could get perfect, clean rear shifts on one of my bikes. It was off by far less than the Park web site seems to suggest is an acceptable tolerance.
I'll take a look at that and try that before Matt's suggestion of cable replacement. I'm almost past frustration and down to curious as to what the problem will end up having been.

Thanks for the help!
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Old 01-08-08, 09:20 AM   #19
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Is the rear shift housing the same length as the original, or the same length as the one that shifts well?
If the rear housing is too short it can cause erratic shifting.

Al
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Old 01-08-08, 10:42 AM   #20
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Is the rear shift housing the same length as the original, or the same length as the one that shifts well?
If the rear housing is too short it can cause erratic shifting.

Al
Hey Al,
Yeah, my LBS mentioned that as the housing is barely straight before it enters that adjustment ferrule. However, when I compared it to an original stock one, it was actually a hair longer. Go figure, eh?
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Old 01-08-08, 06:31 PM   #21
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There are 2 ways to attatch the cable to a DA rear derailer. make sure you are using the correct one, where the cable does not bend at all. It should exit the housing and run straight all the way past the clamping bolt with NO kinks.

I have seen tons of DA users using the other mounting option for older DA shifters. Also i have seen kinks and small "bends" cause impossible to adjust shifting.

Replace your cables dude, it costs $5 and 2 minues of your time.
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Old 01-08-08, 07:42 PM   #22
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I have seen tons of DA users using the other mounting option for older DA shifters. Also i have seen kinks and small "bends" cause impossible to adjust shifting.

Replace your cables dude, it costs $5 and 2 minues of your time.
Thanks. The cable is mounted properly, and, just to eliminate the question, I replaced the cables AND housings today. Still, same problem. It is soooo FRUSTRATING! It'll shift better (but not perfect) in the small ring, and then get goofy when I switch to the big ring - and then shift weird in BOTH rings. No, it doesn't make sense that the big ring should affect the rear cog, but it does. Particularly when getting into the smaller cogs.

Tomorrow is rear derailleur replacement day. Then, the shifter. Then, the BIKE!

Sorry for the rant. Thanks for the help!
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Old 01-08-08, 08:23 PM   #23
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Keep us posted dude.
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Old 01-08-08, 08:32 PM   #24
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"Took it to LBS - he found the rear derailleur cage to be out of whack - straightened it and it's as bad or worse."

I would try a different derailleur first.
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Old 01-08-08, 08:58 PM   #25
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Chainline?

If it is worse in the big ring, the chain could be catching the ramps on the adjacent cog and getting a lift up when you don't want it. Have the LBS look at that while you're there.
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