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  1. #1
    cs1
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    STI Compatible ft der

    I was planning on moving an old Deore group to a road bike frame I have. Will this front der http://www.nashbar.com/profile.cfm?c...Shimano%20Sale Work with 7 sp STI? If not anyone know where I can source a 28.6 triple ft der? My crank has 46 tooth chainring. Most road ft der's I've seen specify somewhere in the 50-53 tooth range. Thanks

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
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  2. #2
    Small Member maddmaxx's Avatar
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    STI road shifters have a different ratio. The derailleur will try to move from the small ring almost all the way to the large ring on 1 click. I presently run a 105 front derailleur on a 48 tooth large ring and it works fine and might work with a 46. Otherwise you could look for a crankset in the 26, 36, 48 range.

  3. #3
    cs1
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    Quote Originally Posted by maddmaxx
    STI road shifters have a different ratio. The derailleur will try to move from the small ring almost all the way to the large ring on 1 click. I presently run a 105 front derailleur on a 48 tooth large ring and it works fine and might work with a 46. Otherwise you could look for a crankset in the 26, 36, 48 range.
    Thanks, I know the ratio is different. I was looking for a der that could handle a 46 for 48 tooth chainring. The woods are full of one that can handle a 50 or 53. If I used barons, it would be a moot point.

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
    1984 Specialized Stumpjumper, 1986 Specialized Stumpjumper and just way too many projects to list.

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    Quote Originally Posted by cs1
    Thanks, I know the ratio is different. I was looking for a der that could handle a 46 for 48 tooth chainring.
    Tim
    The bike I ride most these days has a 105 FD and 46 chainring. Not even the slightest problem.

  5. #5
    cs1
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    Quote Originally Posted by GCRyder
    The bike I ride most these days has a 105 FD and 46 chainring. Not even the slightest problem.
    Are you using a triple or double. 105 ders are very affordable.

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
    1984 Specialized Stumpjumper, 1986 Specialized Stumpjumper and just way too many projects to list.

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    Quote Originally Posted by cs1
    Are you using a triple or double. 105 ders are very affordable.

    Tim
    I'm using the 105 double, with a 46/36 RSX double crankset. Can't say whether the triple version would work as well, but I don't know why it wouldn't.

  7. #7
    'Mizer Cats are INSANE Mentor58's Avatar
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    I've run a 44*32*22 on two different bikes with a 105 FD and a Tiagra FD with STI. It took just a little bit of tuning, but no real problems. Yea, it looks sort of strange, the curve of the derailer doesn't come close to matching the curve of the chainring, but it's more than functional. Shifts UP the Crank aren't as smooth and slick as my Ultegra bike, but I've never had it fail.

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  8. #8
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    I curently have 44*32*22 with Tiagra FD and 9 speed STI.

    Shifting is fine, although I have to trim the FD while in middle chainring and inner/outermost sprockets. This is because the der' is about 5mm higher than it should due to the location of the seat tube bottle mount braze on.

  9. #9
    cs1
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    Quote Originally Posted by Sholto
    I curently have 44*32*22 with Tiagra FD and 9 speed STI.

    Shifting is fine, although I have to trim the FD while in middle chainring and inner/outermost sprockets. This is because the der' is about 5mm higher than it should due to the location of the seat tube bottle mount braze on.
    I would imagine that a 46 or 48 tooth chainringe would put the der in a better position then. Thanks, Tiagra der's are very affordable.

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
    1984 Specialized Stumpjumper, 1986 Specialized Stumpjumper and just way too many projects to list.

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