HELP! Chain rubbing on Front Derailler!

Discussion in 'Cycling Equipment' started by vkhalsa, Jun 5, 2004.

  1. vkhalsa

    vkhalsa New Member

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    my chain rubs on the outside of the front derailler (Shimano Ultegra) when i'm on the inner front cog and any of the lower 3 (outer) cogs in the back. It's a trek 5200 and i don't think there's a rotational adjustment if that's what needs to be adjusted. I would rather do it my self than take it back to my LBS if anyone out there can help.
     
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  2. boudreaux

    boudreaux New Member

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    Ya tried using the trim function in the shifter.Small click rather than the big one to change rings.
     
  3. vkhalsa

    vkhalsa New Member

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    thx for responding, ya i just tried that. it doesn't help.
     
  4. boudreaux

    boudreaux New Member

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    That's it's job if the derailer is adjusted properly.
     
  5. lokstah

    lokstah New Member

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    inner ring (front) + outer cogs (rear) = likely rubbing situation

    Same goes for the reverse. Essentially a shifting no-no; undue stress on the drivetrain. Right, Boudreaux?
     
  6. vkhalsa

    vkhalsa New Member

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    i totally agree it is a "shifting no-no" to be on either outer/inner or inner/outer. but i don't think it should be rubbing when i'm on the second to outer on the rear and inner front. (it also slightly rubs on the third from the outer in the back).
     
  7. lokstah

    lokstah New Member

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    I'd say it's not terribly uncommon for some rub to occur one or two cogs in from the extreme (high or low) if you're in the wrong chainring up front.

    A properly set-up trim position should permit you to go all the way (though you shouldn't do it) -- when you say you've "tried that and it doesn't help," what does that mean, exactly? Does that mean that you perform a half-click on the shifter and you distinctly see the derailleur move into a corrected position, only not far enough to fix the rub?

    Or does it not click into an adjusted trim position at all, simply springing back to the original location?
     
  8. boudreaux

    boudreaux New Member

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    The small/small is a no no.Assuming you have rub in the next 2 smaller and the derailer is properly adjusted,and you are using the trim properly, then you just live with it.
     
  9. vkhalsa

    vkhalsa New Member

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    ya so i gave up playing with the trim and took it in to my LBS and it ended up being a bad cable. He changed the cable and now it works perfectly.
     
  10. lokstah

    lokstah New Member

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    Glad to hear it -- happy riding!
     
  11. seriousturtle

    seriousturtle New Member

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    try not to use inner f.der and the small 3 cogs in back, because of rub but also for the unnecessary stress put on the chain from the lateral angle. the trim would help the the rub, but doesn't change the angle the chain is coming off the chainring. save the life of the chain, its pretty important.

    ~the turtle
     
  12. boudreaux

    boudreaux New Member

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    Hooey
     
  13. lokstah

    lokstah New Member

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    Have you reached your birthyear in number of posts yet, Boudreaux?

    ;)
     
  14. gclariosa

    gclariosa New Member

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    1. release the front derailleur cables
    2. shift to the biggest rear cog.
    3. adjust any of the 2 front derailleur adjustment screws to eliminate rubbing on the front derailleur plate.
    4. reinstall cable.
    5. shift to the big ring .
    6. adjust screws just enough to eliminate chain from skipping over the big ring.
    7. shift to the small ring and smallest cog.
     
  15. boudreaux

    boudreaux New Member

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    1a) make sure derailer is at proper height and properly aligned. 2a) have shifter in SMALL chainring position. 3a) adjust LOW limit screw so that the chain clears the INNER plate by about .5-1mm. 6a) adjust HI limit so chain shifts smoothly to big ring,but not so loose that it overshifts it. Better to just refer em to www.park too.com rather than muck most of it up.
     
  16. Rudy

    Rudy New Member

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    :) :)
     
  17. lokstah

    lokstah New Member

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    Actually, I'm curious about this. The debate here -- seriousturtle's contention that severe chain angles can conrtibute to wear, and boudreaux's assesment of hooey -- is one I don't have an informed opinion on and I was wondering if you guys wanted to weigh in a little more.

    It certainly seems that pulling the chain across gears in increasingly extreme angles would accelerate wear -- there's something intuitive to that claim. Boudreaux, what's your thinking? I'm openly acknowledging the value of your weathered cranium. Spill the beans, old man.
     
  18. meehs

    meehs New Member

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    I'm not really sure why boudreaux threw down the "hooey" call on that one... I suspect it's because seriousturtle said that you shouldn't use the three small cogs in the rear with the small chainring up front. That's a bit excessive. I've always heard not to use just the smallest cog in back with the small chainring.

    Anything other than a straight chainline does put a side load on the chain and also effects the efficiency of the drivetrain. Inefficiency and chain-stress increases as the angle of the chain increases. This does not however effect chain-wear in the traditional sense (increased pitch distance).
     
  19. Aztec

    Aztec New Member

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    Me? I never worry about chain wear. At only $30 to $50, I don't really care whether it lasts for 2000 or as much as 6000 miles. So, I'll grind away for awhile in big/big or small/small if I am too lazy to shift (or in a hurry). I won't target those combos, though.

    As for more wear in the first place, I'd guess that the racket it makes (much more in big/big than small/small) is in indicator of increased wear/friction.
     
  20. RC2

    RC2 New Member

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    I'd agree somewhat with you there... but as someone who has experienced a chain break in the boonies, I want to do what I can to ensure a long life. It's pretty easy to make it a habit to shift from small chainring to middle before you get to smallest/smallest. Same with biggest/biggest.
     
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