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  1. #1
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    FD-M760 XT issues

    Ok, I meticuoulsy followed all the instructions on how to install the XT front derail. on my Epic. However, it seems that I just can't get that bad boy adjusted just right. Here's my problem, when I'm in the 2nd chainring up front, the chain rubs against the derail. when I'm in the 1rst and 9th cogs. I can see if it was rubbing on just one side (1rst OR 9th) but not both. I have spent hours adjusting this thing... raising and lowering the derail, adjusting the cable... but I can't seem to fix this issue. What makes this bad is when I'm in the 3rd chainring and the 8th and 9th cogs, the chain rubs against the derail. like there's no tomorrow. Sure, normally you would just change where on the cable you clamp to (sorry for the lack of terminology) but remember, it already rubs against when in 2nd chainring and 1rst cog; if I adjust the cable to compensate for the 3rd c.ring/8-9cog rub (against the derail), then I'll start rubbing against the derail when I'm in the 2nd c.ring/1-3cog positions.

    I never had issues with this before... I had on my previous bike a FD-M752 and never accounted this (on a Specialized Stumpy Pro FSR). I think it has something to do with my shifters. I want to run SRAM Rocket Halfpipes, but I was sent the wrong ones--so I've been using XT Rapidfires (they were on my Stumpy Pro before I switched that bike to the Rocket Halfpipes). The new shifters should be finally coming soon, but I have a race this weekend and I don't want to change the shifters beforehand as I've gotten used to the XTs over the past few weeks.

    So, what advice do ya'll have? I can't see how to correct the issue if it's rubbing against the Front derail. on both the low and high cogs... Can it be that the shifters are just worn out (they were raced on before I had them)?
    waaahoooooooooooooooooo

    Calvin : Ahhh, another bowl of Chocolate Frosted Sugar Bombs! The second bowl is always the best! The pleasure of my first bowl is diminished by the anticipation of future bowls and by the end of my third bowl, I usually feel sick.
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  2. #2
    sadly, like the element
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    If you still have the F-M752 compare the cage widths. The M760s are closer together from what I've gathered. I always had rubbing issues with the out cogs while in the middle, and then the cogs on bad chainlines when in either the small small or big big combos. I just learned to not shift into those combos, they're terrible chainlines and wear your drivetrain out quickly. If you want to remedy it, get a twist grip SRAM shifter so you can trim the derailer (which sounds like you're getting). As for rapid fire/triggers they don't have trim options so what you set is what you get.

    I don't understand how you think it's the shifter, if when it's on one ring in the front and you don't touch the front shifter and then shift the rear. When things start happening like rubbing, you haven't moved the front derailer cage at all, the newer derailer just has a smaller cage to speed up shifting.

  3. #3
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    Yea, good point... I hadn't thought about the cage width being changed. I'm just tired of getting to a road stretch of a ride and getting rub in 3rd chainring and 8/9cog. But yea, thanks for the input... guess I'll just duke it out until I get the grippys installed!
    waaahoooooooooooooooooo

    Calvin : Ahhh, another bowl of Chocolate Frosted Sugar Bombs! The second bowl is always the best! The pleasure of my first bowl is diminished by the anticipation of future bowls and by the end of my third bowl, I usually feel sick.
    Hobbes : Maybe you shouldn't use chocolate milk.
    Calvin : I tried Cola, but the bubbles went up my nose.

  4. #4
    Sublime Absurdity
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    Quote Originally Posted by ickyickyptngzutboing
    Yea, good point... I hadn't thought about the cage width being changed. I'm just tired of getting to a road stretch of a ride and getting rub in 3rd chainring and 8/9cog. But yea, thanks for the input... guess I'll just duke it out until I get the grippys installed!
    I have the exact same problem. Like you, I usually only use the 8/9 cog on the road. With trigger shifters, you can push against the paddle even though it is in the big ring and it moves the der just enough to prevent the rub. I hope that someone knows the solution to this one...
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  5. #5
    Chrome Toaster
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    First off make sure the derrailleur is completely parallel to the rings and there is between a 1mm - 3mm (the closer to 1mm the better) gap between the bottom lip of the cage and the large ring when the outer plate of the derr is directly over the big ring. The upper part of the cage is slightly wider so if the thing is placed too high the chain will ride in the narrower lower part and rub.

    The shifters play no role in this. The indexing on the rockets or XT will be the same so its just a matter of setting them up to shift correctly. The rub however is completely an alignment issue which needs to be solved first.

  6. #6
    Chrome Toaster
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    One question, does the chain rub while setting the bike on a stand or while you ride?
    The reason I ask is because the derr has a range in which it will not rub around 66-69 degrees in relation to the clamp. In frames with BB's in high relation to the rear axle this means the chain will rub when being set on the stand with the suspension topped out but once you sit and the suspension sags the chain falls into the correct spot and will not rub.

  7. #7
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    Rubs on both. I had that derail brand new... with the piece of plastic tap on it showing the correct clearance. I set it up according to the marks on the plastic (the 1mm gap you're talking about above). Looking at my bike right now I have about a 1.5-2mm gap between the outer plate and the largest ring. However, the derailleur does look like it can be straightened out a little bit (looks like it's rotated outwards by less than a degree or two--however, that should give me more "clearance" on the smaller cogs).

    Yea, sodade, the only way to eliminate the rub is by pushing on the paddle of the shifter. Could it be a bad chainline? I installed a XT760 HT II bottom bracket/crankset and it came with a few spacers. My last bike had a spacer on both sides and I repeated the practice with my new bike (S-Works Epic if it's of any help). Any more thoughts?
    waaahoooooooooooooooooo

    Calvin : Ahhh, another bowl of Chocolate Frosted Sugar Bombs! The second bowl is always the best! The pleasure of my first bowl is diminished by the anticipation of future bowls and by the end of my third bowl, I usually feel sick.
    Hobbes : Maybe you shouldn't use chocolate milk.
    Calvin : I tried Cola, but the bubbles went up my nose.

  8. #8
    Chrome Toaster
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    Quote Originally Posted by ickyickyptngzutboing
    Rubs on both. I had that derail brand new... with the piece of plastic tap on it showing the correct clearance. I set it up according to the marks on the plastic (the 1mm gap you're talking about above). Looking at my bike right now I have about a 1.5-2mm gap between the outer plate and the largest ring. However, the derailleur does look like it can be straightened out a little bit (looks like it's rotated outwards by less than a degree or two--however, that should give me more "clearance" on the smaller cogs).

    Yea, sodade, the only way to eliminate the rub is by pushing on the paddle of the shifter. Could it be a bad chainline? I installed a XT760 HT II bottom bracket/crankset and it came with a few spacers. My last bike had a spacer on both sides and I repeated the practice with my new bike (S-Works Epic if it's of any help). Any more thoughts?
    Its certainle possible to be a chainline issue. How did you arange the BB spacers? Is the Epic a 68mm or 73mm BB shell?

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