Rear derailleur question on my 29er.- Mtbr.com
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  1. #1
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    Rear derailleur question on my 29er.

    Hello, I just bought a GF Mamba. It came with an 8 spd setup and I recently upgraded it to 9 speed. It already had a sram x5 on the back so all I needed was a casette, shifter, and chain. Once I put it all together I had a problem. When in the smaller chainring and smaller cogs the arm on the deraileur comes all the way back and the chain rides on itself. Someone told me I need a derailleur with a longer arm.

    Now I am trying to find out if the x.5 that came on the bike is a medium or long cage. Is there a marking on it or some type of identifier or a measurement on cage length? On myine it is, center of pulley to center of pulley approx 3 7/8'' and from end to end of the cage is 5".

    If it helps my cassette is 12-36 and rings are 22 32 44
    Thanks for your help.

  2. #2
    dru
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    How much chain do you have? If you have it in big/big the cage should be stretched forward very much. What you are describing sounds like you've got a chain that needs a few links taken out. btw, in small/small the cage will be pretty close to what you described.

    Drew
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  3. #3
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    When in big big the cage is at about a 45 degree angle back towards the chain rings.

    When in small chain ring the chain will rub back on its self at the 3rd smallest cog.

    I was thinking of trying to remove the link but i am afraid it will be too short. With the cage position above do you thing there is room to remove a link? or does it sound like I have a medium cage and need a long one?

  4. #4
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    Your chain is way too long. A longer deraileur cage won't change that. (yours is already a long cage) Remove just enough links that the chain won't touch itself when in the small-small combo.
    Worked at Trek/Fisher dealer 2008-2013. Only a little biased.

  5. #5
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    Thanks for your help.

  6. #6
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    Question:
    I am building my 29er. And will a 12-36t Shimano cassette work with a Sram X9, X0 9 speed rear derailleur?

    Thanks.

  7. #7
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    Quote Originally Posted by boxedrn View Post
    Question:
    I am building my 29er. And will a 12-36t Shimano cassette work with a Sram X9, X0 9 speed rear derailleur?

    Thanks.
    Yep. That's exactly what's on my bike.
    I like turtles

  8. #8
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    So who rides with a 22 granny and a 36 tooth on the cassette?? Seems a bit overkill there...
    CyclingCentralVa.org

  9. #9
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    Sorry for not mentioning, I plan to run a single chain ring up front, 32t.

    Thank you for your reply.

  10. #10
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    Quote Originally Posted by DavidR1 View Post
    So who rides with a 22 granny and a 36 tooth on the cassette?? Seems a bit overkill there...
    I put an 11-36 cassette on my bike and ended up with a 22 to 36 IF I ever go to my granny. It's such overkill I can't use it. On the rare occasion I go to the granny ring, I have to shift to the third cog.
    I like turtles

  11. #11
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    Quote Originally Posted by DavidR1 View Post
    So who rides with a 22 granny and a 36 tooth on the cassette?? Seems a bit overkill there...
    I prefer a 20T granny with a 36T.... on my Fat Bike.

  12. #12
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    Quote Originally Posted by boxedrn View Post
    Sorry for not mentioning, I plan to run a single chain ring up front, 32t.

    Thank you for your reply.
    Once you install your 32t chainring, adjust your chain length (according to the directions that should have come with your drivetrain parts). Sounds like this could be your problem.

    And yes, just having a 32t ring makes a difference.
    CyclingCentralVa.org

  13. #13
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    Quote Originally Posted by DavidR1 View Post
    Once you install your 32t chainring, adjust your chain length (according to the directions that should have come with your drivetrain parts). Sounds like this could be your problem.

    And yes, just having a 32t ring makes a difference.

    Hi David,

    Thank you for your input. What are the problems will i encounter using this kind of
    set up 12-36 (9speed) and 32t single chainring up front?

    What do you suggest I use?

    Just want everything right before I start buying the parts.

    Thank You.

    Lem

  14. #14
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    No problems, as this 1x9 setup is on my gf's Mamba also. You just need to remove some links in the chain. Basically wrap new chain around chainring and largest cog, see where they meet, and add 2 links then remove the extra chain not needed and assemble your chain.

    You may want to look at if a shorter cage will work in the rear, and possibly a guide up front. I used a RaceFace single speed ring up front, she's yet to drop a chain.

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