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  1. #1
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    Question on adjusting front derailleur

    I have been fighting with adjusting my dura-ace 7900 FD. I have the Park Tool Big Blue Book and have searched the internet looking for information, but I am still not happy with how it is shifting.

    When I go to shift from the big ring to the small ring it takes quite a bit of pressure to make the transfer on the shifter and it seem's to snap real hard when it shifts down. When the bike was new everything was way smoother. Any suggestion are appreciated..
    Current Rides
    2006 Lemond Versailles, mix of Ultegra and 105
    2012 Litespeed L1 Dura Ace

  2. #2
    RoadBikeReview Member
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    Is it possible that the cable is sticking somewhere? Perhaps one of the ferrules is off-track? This degradation happened slowly over time, or did you change something recently? It could also be that the shifter is gummed up... you could try spraying some lubricant in there (plenty of how-to's on youtube).

  3. #3
    'brifter' is a lame word.
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    If I had to guess i'd say you have way too much cable tension. Common mistake w/ 7900.
    i work for some bike racers...
    2013 Trek Madone 5.9 w/ '12 SRAM Red
    2010 Cervelo T1 sprint bike
    Ruger 10-22TD
    Smith&Wesson M&P 15-22
    Smith&Wesson M&P 9
    oh, those belong in another forum

  4. #4
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    Quote Originally Posted by cxwrench View Post
    If I had to guess i'd say you have way too much cable tension. Common mistake w/ 7900.
    When I am in the small ring the cable seems to be fairly loose, maybe I will try to back it off just a bit, thanks for the input.

    The bike is basically new with maybe 1500 miles on it, so the shifters and cable are not gummed up, the reason I have been playing with the adjustment is I changed the front crankset from a FSA to a Dura-Ace
    Current Rides
    2006 Lemond Versailles, mix of Ultegra and 105
    2012 Litespeed L1 Dura Ace

  5. #5
    'brifter' is a lame word.
    Reputation: cxwrench's Avatar
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    It seems that if you set up 7900 'normally', (pulling the cable tightly) that the derailleur will hit it's limit screw before the shifter reaches the catch on the ratchet. Almost like the shifter pulls more cable than it should. Try what would seem to be a crazy loose cable, and see what happens. What i look for is the shifter holding the big ring position and not dropping the chain back down, and the front derailleur moving all the way over and then not moving at all when you let go of the shifter. If the cable is too tight, the shifter won't catch. If it's too loose the front derailleur will shift to the big ring then move very slightly back and probably rub. Adjust w/ barrel adjuster.
    i work for some bike racers...
    2013 Trek Madone 5.9 w/ '12 SRAM Red
    2010 Cervelo T1 sprint bike
    Ruger 10-22TD
    Smith&Wesson M&P 15-22
    Smith&Wesson M&P 9
    oh, those belong in another forum

  6. #6
    wim
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    Quote Originally Posted by lhartle1 View Post
    it seem's to snap real hard when it shifts down.
    Actually, that would indicate that things are moving a bit more freely now than they were before. The downshift of your front derailleur is powered by its very strong spring, with that action very similar to the trigger mechanism action of a firearm. "Snapping real hard" on the downshift is exactly what is supposed to happen.

  7. #7
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    Quote Originally Posted by wim View Post
    Actually, that would indicate that things are moving a bit more freely now than they were before. The downshift of your front derailleur is powered by its very strong spring, with that action very similar to the trigger mechanism action of a firearm. "Snapping real hard" on the downshift is exactly what is supposed to happen.
    I was reading it as if there was a lot of resistance and then, finally, a sudden give... rather than the snap of a spring. Perhaps the OP can clarify? I think cxwrench is likely right about it being a cable tension issue.

  8. #8
    wim
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    Quote Originally Posted by headloss View Post
    I was reading it as if there was a lot of resistance and then, finally, a sudden give... rather than the snap of a spring.
    Well, there's always some resistance at the shift paddle. And you're right—if the cable tension is too high, that resistance can be more than you'd like. But with Shimano front derailleurs, the motion of the derailleur will always be a sudden snap the instant the cable is released inside the shifter. You can't gently lower a Shimano front derailleur from the large ring to the small ring position.

    I can't know if this applies to the OP. But sometimes, people who shift their bike on a repair stand think there's something wrong when in fact there's not. The reason is that your hand position as you make the repair stand shift is is much more awkward and less powerful from the hand position as you ride, and that more often than not, the cadence at which you make the repair stand shift is much lower than the cadence at which you make your road shift. Just thinking out loud here, boring afternoon.

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