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  1. #1
    emi is offline
    Join Date
    Jul 2011
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    Tandem use of Shimano XTR M980 Rear Derailleur 10 SPD SGS model.


    I am new to this site.

    I recently purchased a used tandem and need to update for more hilly use.
    The Litespeed tandem has a Wound Up X-2 Front Fork. Tandem used for about 2,000 miles. Avid disk brakes.

    Old rear 10 speed cluster, came with the bike, 11-25 gears.
    Ultegra Rear Derailleur came with the bike

    I now have a Deore XT CS-M771-10 11-34 gear on the rear.

    I need to change for the larger size rear gears.

    Can I change to a 10 speed XT-M772 SGS Rear Derailleur for an
    Shimano XTR M980 Rear Derailleur 10 SPD SGS model.

    Can I use a Shimano XTR CN-M980 10 Speed Chain to replace
    Shimano CN-HG94 MTB 10 Speed Chain?
    Can I switch between the two chains??
    One cost more, should that be better?
    Will I need a longer length chain or to ad links to the chain for the larger 34 model?

    These are to be used on my tandem with Ultegra .STI.
    10 speed Shifters with Flight Deck feature.
    I co not want to change from these .STI. brake/shifers.

    I want to know what will work and advantages of the different options.

    What other options do I have.

    Thought on what would be best for me.

    Our combined weight is 270 pounds.

    Thank you,


  2. #2
    Tandem Mountain Climber
    Join Date
    Mar 2007
    San Mateo, CA
    My Bikes
    Calfee Tandem, Custom CAAD9 BB30, 90 Santana Arriva Tandem, 02 CAAD4 errand bike, 87 Cannondale "Black Lightning"
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    the dynasys stuff does not work with road 10 speed levers. The 9-speed XT/XTR/etc RDs works perfectly with the 10-speed cassette and 10-speed levers.

    The levers and cassette dictate the number of speeds, not the RD. You just need any RD that is compatible with the cable pull ratio of the levers. The 9-speed RD is, the dynasys is not.

    I am running the M772 SGS with Ultegra 6703 levers and Sram XX 11-32 10 speed cassette
    Last edited by uspspro; 07-17-11 at 03:27 PM.

  3. #3
    Gear Combo Guru Chris_W's Avatar
    Join Date
    May 2007
    My Bikes
    Spec' Tarmac (road), Ridley Fenix (commuter & fast tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder)
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    Yes, you'll need to get a longer chain. Any 10-speed chain should work. The new Shimano 10-speed MTB chains should be optimized to work with the new cassette, and should also work well with whatever chainrings you have. Any other 10-speed chain should also work reasonably well, though.

    As said above, stay away from the DynaSys / 10-speed MTB rear derailleurs, stick with something labeled as 9-speed.

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