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  1. #1
    Holy crip he's a crapple
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    Front detailleur shim

    How should I measure this, and where can I buy one?

    The bike my new front derailleur came off of used a 27.2 seatpost, and the bike I want to put it on uses a 26.4.

    It's a DA FD-7700 clamp on, if that matters.
    2012 Trek Madone 5.2 64cm - 1984 68cm KHS 9spd/sti swapped to DA 7700
    2013 Trek Rumblefish Elite 23" - 2004 Santa Cruz Bullitt 21.5"

  2. #2
    自転車整備士 oldskoolwrench's Avatar
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    The clamp diameter should be stamped on the inside of the derailleur clamp, and is determined by the diameter of the Seat Tube, not the seat post.
    There are three sizes of clamps; 28.6, 31.8, and 34.9 mm. Shims to make the larger clamp sizes work on smaller seat tubes are available, but only
    to a degree.

    Find out the clamp size, and someone will advise you forthwith.

  3. #3
    Holy crip he's a crapple
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    Old FD is stamped 28.6, new FD is stamped 31.8
    2012 Trek Madone 5.2 64cm - 1984 68cm KHS 9spd/sti swapped to DA 7700
    2013 Trek Rumblefish Elite 23" - 2004 Santa Cruz Bullitt 21.5"

  4. #4
    Senior Member JonathanGennick's Avatar
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    Front detailleur shim

    Shimano derailleur? Your local shop probably has shims laying around.

  5. #5
    Senior Member Shimagnolo's Avatar
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  6. #6
    Holy crip he's a crapple
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    Quote Originally Posted by JonathanGennick View Post
    Shimano derailleur? Your local shop probably has shims laying around.
    I tried both local shops, one did not have the right size and would need to order (thanks I can do that myself and avoid the return trip) and the other shop only stocks bikes/helmets/shoes/tires/tubes unfortunately, no parts.

    thanks for the link to universalcycles, looks like the $6 s-type 31.8 to 28.6 is what I need.
    2012 Trek Madone 5.2 64cm - 1984 68cm KHS 9spd/sti swapped to DA 7700
    2013 Trek Rumblefish Elite 23" - 2004 Santa Cruz Bullitt 21.5"

  7. #7
    Senior Member JonathanGennick's Avatar
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    Had no idea those were sold separately. Learn something new every day, I guess.

  8. #8
    bike whisperer Kimmo's Avatar
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    copy/paste links: http://velospace.org/node/36949 http://velospace.org/node/47746 http://velospace.org/node/47747
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    I hate how FD hangers aren't considered as de rigeur as RD hangers.

    Clamp-on FDs look nearly as crappy as a RD claw to me.

    And they create this problem.

    The issue with integral FD hangers about an appropriate height can be addressed by making it a bit taller, for a start. Or by making it not really integral, like most carbon frames where it's rivetted or preferably bolted on through slotted holes.

  9. #9
    Holy crip he's a crapple
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    looking at my new FD closer I've realized it's actually a braze on mounted style with a shimano braze on 31.8 adapter, so I just ordered a 'problem solvers' braze on to 28.6 FD adapter. I think that will be cleaner/lighter and easier to setup than the 31.8 with a shim.

    I agree, I think a braze on of the frame is a better idea, if the FD's were slotted for height adjustment with different chainrings it would be a whole lot easier!
    2012 Trek Madone 5.2 64cm - 1984 68cm KHS 9spd/sti swapped to DA 7700
    2013 Trek Rumblefish Elite 23" - 2004 Santa Cruz Bullitt 21.5"

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