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  1. #1
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    Ping: Shimano Ride Support

    or anyone else with an idea regarding:

    Front derailleur adjustment.

    Here we go,
    Drive train all 08 XT, trigger shifters, Shadow rear, XT front (FD M-770), SRAM PC-991 chain. Frame 08 Intense 5.5 size small.

    So I followed all the mounting and adjustment instructions from Shimano, as well as my own 20+ years of wrenching experience and find that I have small problem with the FD. If I adjust the FD to not rub the inside of the cage in the small ring/large cog and middle ring/large cog, I get rub on the outside plate in the middle ring/small cog and large ring small cog.

    What am I missing? Cable tension on initial set up seems good, and the shifting is fine. Whichever way I have the FD set to eliminate either of the "rubs", I can use the barrel adjuster to eliminate the other "rub". But I want to get trid of the rub without using the barrel adjuster.

    Thanks in advance.
    I have one firm belief about the American political system, God is a Republican and Santa Claus is a Democrat P.J. O'Rourke





  2. #2
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    I too, have worked on front dérailleurs since 1988. They can be a PITA. One degree of rotation on the frame can make it work, or not.

    I usually give up before success. I adjust it to not rub in the large rear cog. I do this because I can't hear the rub on the small cogs, because I'm going fast. If it rubs while climbing, it is surely slowing me down. Also, i rarely use cog 11 on the back when I am in the middle ring. I am in the big ring by then.

    Another option is to go gorilla, get some channel locks and bend the cage so it's just a bit wider.

  3. #3
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    Quote Originally Posted by laurenlex
    I too, have worked on front dérailleurs since 1988. They can be a PITA. One degree of rotation on the frame can make it work, or not.

    I usually give up before success. I adjust it to not rub in the large rear cog. I do this because I can't hear the rub on the small cogs, because I'm going fast. If it rubs while climbing, it is surely slowing me down. Also, i rarely use cog 11 on the back when I am in the middle ring. I am in the big ring by then.

    Another option is to go gorilla, get some channel locks and bend the cage so it's just a bit wider.
    I try to go untill success.
    I usually adjust to not rub when climbing too. Like you said it must be slowing me down. And I don't usually use middle/small, but it rubs in big/small, also.
    I'm holding off before I go gorilla, but thanks.
    I have one firm belief about the American political system, God is a Republican and Santa Claus is a Democrat P.J. O'Rourke





  4. #4
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    I would try adjusting the FD a little bit off parallel with the chain rings.
    I get the probelm on the stand, but I can usually fix it, once the suspension compresses I am fine.

    If neccessary I adjust for rub on the inside plate large chain ring to large cog. I really have screwed up if I end up in this combo.

  5. #5
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    Quote Originally Posted by jeffscott
    I would try adjusting the FD a little bit off parallel with the chain rings.
    Interesting. I always try to get the cage parallel to the rings, but I almost always end up with rub somewhere.

    Which way usually solves the problem? Point the rear of the cage slightly outwards? Or slightly inwards?

  6. #6
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    Yes parallel to chainrings is the starting point and usually okay.

    On the Rocky ETSX, I end up with the rear of the cage just a hair to the inside On the Element parallel is fine.

    So that is with rub on the outside plate, little chainring to big sprocket.

  7. #7
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    Quote Originally Posted by jeffscott
    Yes parallel to chainrings is the starting point and usually okay.

    On the Rocky ETSX, I end up with the rear of the cage just a hair to the inside On the Element parallel is fine.

    So that is with rub on the outside plate, little chainring to big sprocket.
    i tried the not parallel solution, maybe I'm just not getting it right. If the FD is inwards it creates more rub in the big/little. Outwards is just the opposite.

    What I need is some out-of-the-box thinking. I believe I've tried all the "normal" solutions. Maybe I need to fiddle with the "parallel" adjustment some more
    I have one firm belief about the American political system, God is a Republican and Santa Claus is a Democrat P.J. O'Rourke





  8. #8
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    Sometimes it looks like it is rubbing on the side but it is fubbing on the bottom of the FD...

    Just put it where the FD rubs then move the FD so it just doesn't quite rub, then check the other end.

  9. #9
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    Quote Originally Posted by jeffscott
    Sometimes it looks like it is rubbing on the side but it is fubbing on the bottom of the FD...

    Just put it where the FD rubs then move the FD so it just doesn't quite rub, then check the other end.
    i might have checked that, can't remember. I'll look again. Thanks
    I have one firm belief about the American political system, God is a Republican and Santa Claus is a Democrat P.J. O'Rourke





  10. #10
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    What I have found is slightly contrary to popular technique.

    Don't line up the derailleur by eyeballing the plates. Use some other part of the derailleur like the pivots. If you look closeley you will see the plates are not parallel to the pivots. The rear of the outer plate will stick out past the large chainring more than the front of the outer plate.

    Also check the height. Throughout the rear cassette range make sure the chain rides against the raised section (when downshifting) on the outer plate while in the middle ring.

  11. #11
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    I think you need to dial in more cable tension so the derailleur pulls more to the outside and possibly adjust your limit screw for the big ring so you don't get rub.

  12. #12
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    Quote Originally Posted by presslab
    What I have found is slightly contrary to popular technique.

    Don't line up the derailleur by eyeballing the plates. Use some other part of the derailleur like the pivots. If you look closeley you will see the plates are not parallel to the pivots. The rear of the outer plate will stick out past the large chainring more than the front of the outer plate.

    Also check the height. Throughout the rear cassette range make sure the chain rides against the raised section (when downshifting) on the outer plate while in the middle ring.
    I like the pivot method, I'll try that. Height seems good I'll recheck that too.

    Quote Originally Posted by MikeDee
    I think you need to dial in more cable tension so the derailleur pulls more to the outside and possibly adjust your limit screw for the big ring so you don't get rub.
    I'll check that too.

    Thanks guys. Anymore ideas? Keep 'em coming.
    I have one firm belief about the American political system, God is a Republican and Santa Claus is a Democrat P.J. O'Rourke





  13. #13
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    Ok so I know this is the most predictable answer I could have given but I think you may need to use a Shimano chain. According to QBP the SRAM chain is .2 mm wider than ours is. I suspect that your size small frame has short enough chainstays to make this adjustment very touchy and that wider chain is just too much to handle.

    I do wonder though if this rubbing is only happening in the stand. Full suspension bikes can be tricky to adjust with regards to front shifting because when you sit on the bike the chain is lined up with a different section of the cage plate.

    We used 08 Intense 5.5s as show bikes at Interbike this year and I don't remember having rubbing issues when I built them but I will take a look tomorrow. They were size medium so it may not be that useful though. The build was all the same, SL-M770 / RD-M772, but with a Shimano chain of course.
    Manufacturer - Shimano American Corporation

  14. #14
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    ummmm, but aren't the chainstays all the same length on all bike sizes within a single product design? That would make the chainlines all the same on the various frame sizes. Sometimes very small or very large frames have the seat tube angle change by a degree.

    Of course that gives me an opportunity to ask how long before Shimano makes a Saint/Hone FD specifically for a granny/middle/bashring cranks, something with a cage shaped specifically to work in that long travel FS application so the cage sits closer to the bashring and has a shorter tail to clear swingarms and very wide tires, and has a flare that assumes you want rub-free access from the granny to at least 7 out of 9 cogs, and all 9 cogs from the middle ring. Oh yeah, and if the hi/low limit screws are accessible from the drive side rather than the top where all the suspension linkage is always in the way.

    Or maybe a new front shifter is in order that allows some derailleur adjustment. Maybe a freeride/DH friction thumbshifter for the front 2 rings might be the way to go, so that the FD position can be fine tuned. If you just have to jump between the granny and middle ring, you could just slam it to the upper/lower limits, but in between you'd have full adjustability.

  15. #15
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    Quote Originally Posted by Shimano Ride Support
    Ok so I know this is the most predictable answer I could have given but I think you may need to use a Shimano chain. According to QBP the SRAM chain is .2 mm wider than ours is. I suspect that your size small frame has short enough chainstays to make this adjustment very touchy and that wider chain is just too much to handle.

    I do wonder though if this rubbing is only happening in the stand. Full suspension bikes can be tricky to adjust with regards to front shifting because when you sit on the bike the chain is lined up with a different section of the cage plate.

    We used 08 Intense 5.5s as show bikes at Interbike this year and I don't remember having rubbing issues when I built them but I will take a look tomorrow. They were size medium so it may not be that useful though. The build was all the same, SL-M770 / RD-M772, but with a Shimano chain of course.
    The Sm and Med chainstays ar the same length. I was thinking about the chain being the culprit also, as the rub is occuring both in the stand and on the trail too. All the other adjustments/ideas given so far have been tried/looked at, and found to be ok.
    I'll pick up a new chain and check that. Let me know what you find.
    Thanks.

    Edit: I was also wondering about a "trim" adjustment on the FD, sorta like on road FDs.
    I have one firm belief about the American political system, God is a Republican and Santa Claus is a Democrat P.J. O'Rourke





  16. #16
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    I checked the geometry specs on the Intense web site and you are correct, they are all the same length. As soon as I saw that it was a size small it reminded me of a common problem on road bikes who's chainstays do change length with size. Often all frames of a certain style will be within the minimum chainstay length spec except for the smallest size. That leads to people with small frames having the most problems with cross-over rub. But again, that is mostly for road bikes. The chainstay length listed on the Intense website is about 428mm (conversion done from standard) our minimum chainstay length is 420mm so it is within spec but close.

    I took a look at the show bike and it does not have these problems. If our bike has no cross-over rub and yours does than the problem should lie in the difference between our setups, which would mean the chain. The only other thing I can think of right now that might cause your problems is a mis-aligned frame.

    As for some of those FD suggestions, I don't have a roll in product design but I will pass it along. Some of those suggestions though have already been implemented in the new XT and XTR. The limit screws are all now angled and the trailing edge of the inner cage plate has had all unneccesary material removed for improved tire clearance.
    Manufacturer - Shimano American Corporation

  17. #17
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    The winner is....

    Shimano Ride support. I swapped out chains and bingo, rub was gone. FWIW is initially used a Wipperman connex to put the chain together and the link rubbed really badly, so that pretty much confirmed the problem was the width of the chain. As soon as I rivited the chain together, bingo, problem solved.
    I have one firm belief about the American political system, God is a Republican and Santa Claus is a Democrat P.J. O'Rourke





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