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  1. #1
    Cat 666 fatallightning's Avatar
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    can an 8 speed DA rd handle a 28T cog?

    i know shimano docs say no, but there is often wiggle room. empirical evidence? chain wrap issues? going on a 52/42 chorus double.
    “Oh man, it’s going to take days to kill all these people!” - jens voigt
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  2. #2
    no one cares -holiday76's Avatar
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    velobase says 26 is that max:

    http://velobase.com/ViewSingleCompon...=108&AbsPos=36

    That said, it's worth a try.
    I prefer emails to private messages - holiday76@gmail.com
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  3. #3
    Senior Member RobbieTunes's Avatar
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    Mine isn't supposed to, haven't pushed it.
    I have an 8-sp 600 RD doing just that. Chain length is critical. And I mean you have to have it right on.

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  4. #4
    tuz
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    From my experience with other Shimano dérailleurs (105 and XT), I'd say yes. You will probably have to tighten the B-screw and shorten the chain, as RobbieTunes said. Since the front is a 52-42 the chain wrap should remain ok.

    Give it a try and let us know!
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  5. #5
    Cat 666 fatallightning's Avatar
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    how do i calculate chain length? i believe i have something like an 11-21 mounted now.
    “Oh man, it’s going to take days to kill all these people!” - jens voigt
    Current: Calfee Tetra Pro/ Tiemeyer Signature Track/ Cannondale CAADX/ Trek T1/ Giordana Capella TT
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  6. #6
    tuz
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    Quote Originally Posted by fatallightning View Post
    how do i calculate chain length? i believe i have something like an 11-21 mounted now.
    Your chain is too short: it won't wrap the 52x28. I'd add 3 or 4 links. Ideally the small-small should not be too loose and the big-big not too tight.

    or check here.
    homebuilt commuter, mixte, road and track (+ Ryffranck road)
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