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  1. #1
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    39 tooth cog trouble (actiontec)

    I have a XT shadow rear and I can't seem to get enough b ajustment from the screw.
    I have it screwed all the way in and it still is to close to the cog (1 or 2mm).
    Anyone else have any trouble with this set up?

  2. #2
    ups and downs
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    If that's not a misprint and you're really using a 39T cog then it isn't surprising, they max out at a 34T cog.

  3. #3
    ballbuster
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    I didn't even know...

    Quote Originally Posted by biketuna
    I have a XT shadow rear and I can't seem to get enough b ajustment from the screw.
    I have it screwed all the way in and it still is to close to the cog (1 or 2mm).
    Anyone else have any trouble with this set up?
    There was such a thing as a 39t cog. Careful with that thing... you can break freehubs!


    Since just about every mountain derailleur I've seen has a max tooth size of 34 teeth, if not 32t. It's a wonder it works at all.

    You might just have to cut a couple links out of the chain to bring the derailleur around forward. Be careful with that. I can guarantee you it will bind if you try to shift into the forbidden gear.

  4. #4
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    There are a few people here running 39 tooth cogs here with no issues.
    I have an old XT rear D that I will try next. If I can get this to work I will convert to a 1 x 9.

    www.actiontec.us is the web site for the cogs. They make a few different sizes.

    From my research (on this site) a shimano will adjust to a 39t and a sram will adjust to a 36t. I'll post some pictures when I'm done.

  5. #5
    nnn
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    Why would you need a 39t cog anyway? At a normal cadence in such a ratio you may as well be walking the bike, probably safer
    "Life begins at 140" Richard Burns
    http://www.nikolay-k.com

  6. #6
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    If you run 1x9, the extra range may help.

  7. #7
    Mantis, Paramount, Campy
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    Maybe 1x9 with a 48T ring

    But to address the initial question: Try either flipping the screw around or buing a longer screw.
    *** --- *** --- ***

  8. #8
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    nnn, If I get this to work I can get rid of my front shifter, front D and small ring.

    Shayne, I picked up a longer screw today.

  9. #9
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    It works now. I'll try it out on the trail on Thurday and post some pictures.
    I also added a jumpstop so my chain won't fall off. ( no front D anymore )

    Next project is a 30 tooth middle chainring with 104mm spacing. (www.extralite.com)

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