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I cannot get this Shimano XT rear derailer adjusted properly

9899 Views 12 Replies 6 Participants Last post by HyperBaton, Jun 26, 2009

HyperBaton

Discussion Starter · Jun 23, 2009

This derailer has performed without a problem for 6 months (always adjusted it myself) but recently it's been... well... a *****.

I cannot get it to shift to the largest cog without overshifting into the wheel. But that's the only cable tension that allows for good performance in all the other gears. If I set the cable tension so that in gear 9 the derailer sits nicely under the largest cog, all the other gears are crap and I cannot shift from 1 to 2 using the first click.

When I look at the derailer moving from 8 to 9, it moves waaaaay more (lateral) than from 7 to 8 for example, so it usually skips the 8th gear as well (when adjusted so that it does not overshift the largest cog).

It's a 9-speed XT Shadow derailer '09 with 9-speed XT shifter, so it's not a problem with wrongfully matched derailer/shifter, the bike came stock with these.

I'm awfully confused as to what's happenening here. Any ideas?

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1 - 13 of 13 Posts

perttime

· #2 · Jun 23, 2009

Maybe you have hit the derailer on something and the derailer hanger (attaching derailer to frame) is bent?

That could cause what you are describing. The hanger is there to prevent damage to more expensive parts.

You may be able to straighten the hanger but it is generally a good idea to have a spare, in case you break it.

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HyperBaton

Discussion Starter · #3 · Jun 23, 2009

I checked and the hanger is straight, cogs and pulleys are vertical.

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SteveUK

· #4 · Jun 23, 2009

Just start over. Undo the cable from the derailleur, reset the barrel adjuster on the shifter and set the system up from scratch. You may find these instructions helpful.

You could also remove the end-caps from your cables to make sure that the outers haven't split/deformed. Check all sections of outer for cracks or deformities. When you undo the cable from the derailleur, grab a hold of it and operate the shifter. Does everything move freely?

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HyperBaton

Discussion Starter · #5 · Jun 23, 2009

Yeah, I've started over a couple of times already, making sure the cable is very loosely attached to the derailer when the barrel adjuster is fully turned in. Still no go...

I'll check the outer, end-caps and shifter when I get back in a couple of hours, thanks so far for the tips.

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SteveUK

· #6 · Jun 23, 2009

"...making sure the cable is very loosely attached to the derailer when the barrel adjuster is fully turned in."

I don't understand what you mean by this. Do you mean that the bolt is loose or that cable tension is loose?

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mechBgon

· #7 · Jun 23, 2009

HyperBaton said:
I cannot get it to shift to the largest cog without overshifting into the wheel. But that's the only cable tension that allows for good performance in all the other gears.

Use the low-gear limit screw to stop the RD's stroke directly below the largest cog.

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HyperBaton

Discussion Starter · #8 · Jun 23, 2009

SteveUK said:
"...making sure the cable is very loosely attached to the derailer when the barrel adjuster is fully turned in."

I don't understand what you mean by this. Do you mean that the bolt is loose or that cable tension is loose?

Sorry, I try my best but I'm not a native English speaker. I mean that the cable tension is loose so that I can be sure I can make all the adjustment I need using the barrel adjuster.

mechBgon said:
Use the low-gear limit screw to stop the RD's stroke directly below the largest cog.

Well, the problem is I can't even get to the lowest gear if I do that. The cable tension is too high, it wants to overshift, but can't because the derailer hits the screw, so I can't make the last click on the shifter. And the cable tension is too high because otherwise the other gears do not shift well.

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SteveUK

· #9 · Jun 23, 2009

"Sorry, I try my best but I'm not a native English speaker. I mean that the cable tension is loose so that I can be sure I can make all the adjustment I need using the barrel adjuster."

I'm with you now. It sounds as if your set-up is suffering from you under-compensating the cable tension. Here's something to try:

Reset the shifter adjuster and release the cable bolt. Use the upper (H) limit screw to determine the position of the derailleur directly under the top gear - using the chain as your vertical reference - then pull the cable under the cable bolt, as tight as you can comfortably manage, and tighten the bolt. Shift down to the lowest gear and set the (L) screw, before coming back to the high gear and doing your indexing.

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HyperBaton

Discussion Starter · #10 · Jun 24, 2009

SteveUK said:
Reset the shifter adjuster and release the cable bolt. Use the upper (H) limit screw to determine the position of the derailleur directly under the top gear - using the chain as your vertical reference - then pull the cable under the cable bolt, as tight as you can comfortably manage, and tighten the bolt. Shift down to the lowest gear and set the (L) screw, before coming back to the high gear and doing your indexing.

Sorry for late reply, I'm in the middle of exams, kind of busy.

Okay, I tried to adjust the derailer like this. Results are the same. the derailer just wants to go way to far on the last click, so I can't do the last click, it hits the limit screw. If I index the derailer so I just hit the lowest gear on the 9th click, the first click does nothing. The second click then goes from highest to second highest gear etc. Bad shifting performance ofcourse and skipping of a random gear, because I only need 8 clicks to go through 9 gears.

I really don't understand.

I checked the housings and the middle housing might need replacing, the cable did not go through it very smooth. But a new housing won't fix my problem I guess. It won't change the fact that my derailer likes to go the extra distance

So, what else could be happening here? Could the shifter be bad? Like taking in too much cable? Sounds silly I suppose, but I'm out of ideas.

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KevinB

· #11 · Jun 24, 2009

Have you checked to see if the cable is frayed? In particular, check the cable where it goes in and out of the shifter. (If the frayed section ends up underneath near the end of the travel, that could well pull in some extra cable.) Otherwise, open up the shifter up and look for whatever it is that's pulling in the extra cable.

I'd switch out the bad housing segments too, but that doesn't sound like it's the problem in this case.

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pdlhrd

· #12 · Jun 24, 2009

Try Again

I think you may be starting with too slack a cable. Try this process (which is what SteveUK suggested above). (This assumes you DO NOT have an rapid-rise RD).
1) release pinch bolt and pedal so chain and RD are positioned in smallest cog (i.e. 11T).
2) Pull on cable by hand to tension and simultaneously shift to highest setting on your shifter to make sure the shifter is positioned in high gear (gear 9, or 11T). If you have a visual shift indicator, make sure it is indicated "high gear".
3) Set high-gear limit screw marked "H" so RD can't move past the 11T cog.
At this point do a logic check. Make sure all components are in the position they are supposed to be in- shifter, chain, RD all positioned for high-gear 11T
4) attach cable with pinch bolt and pull the slack out by hand, it should be fairly tight.
5) trying shifting to next gear (13T). You will most likely need to tighten the cable further with the barrel adjuster to get the chain to cleanly move to the next gear. Continue shifting in the 1st 1-3 cogs until the shiftin is smooth. Get the shifting working well up & down by adjusting tension with the barrel adjuster. Once you get the first 11T to 13T shift to happen, you will only need small adjustments to the barrel adjuster. 1/4-1/2 turns.
6) Now gently shift to your largest cog (34t) but don't let the chain go into the spokes. Adjust the limit screw marked "L" to keep the RD from shifting too far.
You can also adjust the L limit at the begining of this process w/o having the cable attached by manually shifting and pedaling. It may help to have someone pedal while you adjust. This can by done by sight. From the back of the bike line the upper pulley up with the bottom of the 34t cog and set the limit screw so it won't go any further (sometimes 1mm to the right is fine too).

I hope this helps. It doesn't sound like you have any thing broken, just out of adjustment.

Here's a Shimano doc that may help too: http://tiny.cc/IrGVE

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HyperBaton

Discussion Starter · #13 · Jun 26, 2009

Well, I seem to have located the problem: A spacer behind the cassette. My rear wheel got smashed some time ago and I borrowed a rear wheel from a friend of mine. I didn't ride for some time, so I completely forgot it might have something to do with it. There was a spacer behind the cassette (on a XT hub), but I didn't think much of it, because on my Mavic hub there is also a spacer (which is even bigger). And that never caused any problems. So just to try something, I removed the spacer, and voila, I could adjust my derailer in a matter of seconds.

Funny how a spacer of just one millimeter can make such a difference? What's the deal with those spacers anyway, how can you tell if you need to put one in and how big it should be? I'm having a new wheel built on an XTR hub and the hub did not come with any spacers, does that mean I don't need to put one behind my cassette?

So I hope that fixed it... Although the motto of my bike usually seems to be: "Fixed... for now."

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