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  1. #1
    Still rockin' those bibs!
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    Shimano 2x XTR 986 Front Derailleur Problem

    OK, so here's the issue. After using an XTR 986 "Race" Front Deraileur for about 4 months, the whole time thinking that this has to be the greatest thing since sliced bread (I mean it shifts up so easy) the shift started to develop some resistance and then a hard "click" sound when shifting into the big ring. Specifics:

    The 986 FD is the one specific to 2x drivetrains.
    I'm using a 26/38 chainring combo on an XT crankset.
    I'm using XTR 980 shifters.
    I'm using the XTR 10-sp chain.

    So upon inspection, I noticed that the chain has worn a deep groove into the derailleur cage, right through the plating, down into the base metal about 1-1.5 mm deep. The "click" came from the chain trying to push up and out of the groove, which has developed a definite shelf-like edge.

    On a good note, I called JensonUSA and they sent me out a new one right away. Regardless, here is what I noticed when I replaced the thing:

    When you shift the front from the small to the big ring, the amount of space between the small ring and the cage is reduced, forcing the chain to slide up onto the inside of the cage, and ultimately catches onto the larger ring. There is a downward sloping wedge on the inside of the cage that essentially deflects the chain, twisting the top outward. From what I can tell, the chain is being pinched between the small ring and the downward sloping wedge shape on the inside of the cage, causing intense friction for a few link passages before the chain is completely derailed. This is causing the wear groove.

    Now, a couple of things:

    - It has occurred to me that the fore/aft position relative to my crankset could be contributing to this problem, dictated by the position of my seat tube. I ride a 2010 Titus El Guapo, but have a 2009 El Guapo with a 9-speed setup and have never noticed such a problem there.

    - The cage on the 986 is smaller / shorter than the cage on the "trail" version which is specific to 3x setups.

    - Finally, I have heard that Shimano's 10-speed chain is directional. When I built up the bike, I let the shop handle my drive train's initial setup, and never bothered to check after they were done. In the beginning, it worked so smoothly and flawlessly the I never imagined there even could be a problem. On breaking the chain to replace the FD, I kept the original orientation, however...

    - I HAVE NOTICED THAT EVEN WITH THE NEW DERAILLEUR, THE SHIFT - PINCH IS STILL QUITE NOTICEABLE AND CAN TELL THAT IT WILL EVENTUALLY LEAD TO THE SAME PROBLEM A FEW MONTHS DOWN THE LINE.

    What to do???

    Thanks in advance,

    Matt
    Last edited by Lycra Matt; 01-09-2012 at 10:51 AM. Reason: typo
    Like half of everything I ride comes out of Jenson. Figure that out.

  2. #2
    Plays with tools
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    Your situation seams rather odd. Is the chain on in the correct direction (logos out)? There are specifications for how slack a seat tube can be before it hampers front shifting but It's pretty much not an issue with standard seat tubes on 26" bikes.

  3. #3
    Still rockin' those bibs!
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    I just checked this morning. The logos are facing out.
    Like half of everything I ride comes out of Jenson. Figure that out.

  4. #4
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    Same Issue

    I know I'm digging up an old thread here, but I've been experiencing the exact same problem on my XTR double setup...just wondering if you've found out anything further or have managed to eliminate the problem at all?

    Thanks - Hedge

  5. #5
    Still rockin' those bibs!
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    No, it's still happening. A few things I've noticed: Shifting my weight forward while climbing steeps makes it go away. Problem is that it's not practical to do this for a long climb. Other than that, I try to limit my use of the absolute granniest gear to when I really need it. Bummer, since otherwise, the 2x10 setup is awesome.
    Like half of everything I ride comes out of Jenson. Figure that out.

  6. #6
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    I'm a noob

    ...I may have figured out why my front derailleur is not behaving...in my haste to set it up, I did not follow the proper installation instructions

    Matt, is your cable being wrapped through the guides on the derailleur body prior to being secured by the pinch bolt? I'm pretty sure that this is my problem as I simply ran the cable from the shifter directly to the pinch bolt. I will check tonight and report back...
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  7. #7
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    Out to lunch

    ..forget my previous post. I went home tonight to mess with front derailleur height. Set at 7mm above the large chain ring (as opposed to 1mm - 3mm suggested), it now shifts fine without snagging the chain on upshifts. The only issue is a slight bit of chain slap on the lower cage when in the 11/28 combo...I can live with that.

  8. #8
    the catalan connection
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    Quote Originally Posted by Hedge72 View Post
    ..forget my previous post. I went home tonight to mess with front derailleur height. Set at 7mm above the large chain ring (as opposed to 1mm - 3mm suggested), it now shifts fine without snagging the chain on upshifts. The only issue is a slight bit of chain slap on the lower cage when in the 11/28 combo...I can live with that.
    Isnīt the derailleur installation height indicated by a sticker on the outer plate? I mean, do you still keep it? Also the plastic block to lock it aligned with the outer cage as you install? I was wondering how do you figured out the correct height otherwise....and how you moved from there...
    "Blessed is the man who, having nothing to say, abstains from giving us wordly evidence of the fact." George Elliot

  9. #9
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    Quote Originally Posted by What&son View Post
    I was wondering how do you figured out the correct height otherwise....and how you moved from there...
    The sticker and block are long gone. All I did was loosen the clamp bolt, nudge the derailleur up a little, tighten and test. Kept this up until I got it to the point where the chain wasn't being pinched between the outer ring and the derailleur back plate on upshifts. This point happened to be about 6-7mm above the outer chainring.

  10. #10
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    So set it up like there's a third ring even though there's only two?

    This makes a little sense, as I had to do that on my old triple setup XTR when I pulled the outer ring and replaced it with a bashguard. Looked kinda high and silly up there, but shifted fine.
    Like half of everything I ride comes out of Jenson. Figure that out.

  11. #11
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    Quote Originally Posted by Lycra Matt View Post
    This makes a little sense, as I had to do that on my old triple setup XTR when I pulled the outer ring and replaced it with a bashguard. Looked kinda high and silly up there, but shifted fine.
    I am having exactly the same problem. My front derailleur is a Shimano XTR 986 Direct Mount. I use it on my Pivot Les 29" with Shimano XT 38x24 Crankset. I already have tried to put the FD in a higher position but the same problem persists. Could anyone help me? Would be possible use the XTR 981 model with my 2x crankset?

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