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  1. #1
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    SRAM 10 speed Front Derailleur Mountain Road Compatibility

    For some time, I had a touring bike built up using a mountain bike frame w/drop bars + STI shifting. While a 9-speed Shimano mountain rear derailleur works fine with STI, in order to get the (mountain) front derailleur to work with the shifters, I needed to use a jtek ratio changing pulley because in the 9 speed world, road shifters pull less cable than mountain shifters w.r.t. the front derailleur. An alternative would be a top-pull road derailleur but those are non-existent (yeah, I know about the umlenker and cyclocross pulleys, more on that below).

    Fast forward to now and I'm switching this bike to 2x10 and using largely SRAM components. SRAM X-9 rear derailleur mates fine with SRAM Force shifters. Now, I'm in the process of trying to select a front derailleur.

    Two things I've tried:
    1) Use my existing 9-speed mountain front derailleur and a pulley. This works okay, but I'd like to lose the pulley if possible. Furthermore, the tension on the shift cable is pretty extreme.
    2) Try using a road front derailleur. I combined a SRAM Force front derailleur and an umlenker. Getting this to work with my setup (crankset) is troublesome and requires serious dremmeling of the derailleur "limit" mechanism to allow it to move further outboard. It works, again, just okay, and because it is so far outboard beyond the normal tolerance, you are really pulling against a pretty taut spring - again lots of extreme cable tension.

    What I'd like to know/try:
    Are SRAM 10 speed (2x10) mountain/road FRONT derailleurs compatible in terms of how much cable pull they expect. That is, can I use an X.9 2011 2x10 front derailleur with SRAM Force shifters??

  2. #2
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    bump. I'd like to confirm this as well for an upcoming monstercross build.

  3. #3
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    I spoke to SRAM about this and they told me it wouldn't work. So, I ended up sticking with the old 9-speed (mtn) derailleur and a pulley. I would still love to lose the pulley if there is a combination that would work.

  4. #4
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    Hello.....

    Quote Originally Posted by arnobarno
    I spoke to SRAM about this and they told me it wouldn't work. So, I ended up sticking with the old 9-speed (mtn) derailleur and a pulley. I would still love to lose the pulley if there is a combination that would work.
    I'm in the same situation here using a SRAM Force shifters on a mountain bike frame. Did they say specifically why this would not work?

    Which 9-sp mtn derailleur are you using on the 2x10 crank?

    Thanks,

    EndUser
    My advice and $3 will buy you nothing more than a tunafish sandwich.

  5. #5
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    I'm using a 9 speed XTR front derailleur with a 34-48 XT mountain "trekking" crank (originally comes as 26-36-48 but I removed the 26 and swapped the 36 for a 34). This is sold as a 9 speed crankset but works perfectly wtih a 10 speed chain.

    This crank has its own issues - mostly in the way Shimano puts a spacer on the axle to shift the rings outboard so as to not interfere with the frame. But, of course, this puts one leg further outboard than the other and not even. If your frame has clearance, you can play around with the bb spacers to compensate for this problem.

    FWIW - This entire setup works well with no problems. I just completed a 500 mile self supported tour with some tough grades (sustained 12-22%).

  6. #6
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    The reason they said it won't work is the cable pull ratios are not the same.

  7. #7
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    Sram's 10 speed lineup - both road and MTB, use exact actuation technology. Its still their "1:1 ratio" but the exact actuation is more precise. The 9 speed stuff is "1:1" as well, but doesn't use exact actuation.

    Exact Actuation is more precise for the narrower 10 speed stuff, where the 9 speed doesn't need it.

    You can use 10 speed MTB derailleurs with 10 speed road shifters though. And vice versa.

  8. #8
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    Err, actually, you can mix and match road/mtb rear derailleurs. You cannot mix and match front derailleurs as there is still a SUBSTANTIAL difference in cable pull between road and mountain.

  9. #9
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    This is how I interpret mixing parts

    Quote Originally Posted by arnobarno
    Err, actually, you can mix and match road/mtb rear derailleurs. You cannot mix and match front derailleurs as there is still a SUBSTANTIAL difference in cable pull between road and mountain.
    Thanks for the info.

    I'm planning on using a SRAM XO 2X10 Crank and trying a front Force road derailleur (like you attempted) in combination with Force road shifters. I don't have the cranks yet, but I appreciate the issue you experienced with the wider Q-factor of the MTB cranks and use of the road derailleur. I'm hoping that the outer ring is closer in board on the 2X10 than the traditional 3X9 crank and that the road derailleur will stretch enough to work.

    I gather from your message that you did not try a SRAM 2x10 Mountain Front Derailluer with your force shifters just to see what would happen? I'm still curious because the chain-ring gap should be the same on a 2X10 road system as they are on the 2X10 mountain system. How different could the cable pull actually between Mountain Road front derailleurs? I'm going to have a chance to try this (along with the force front)..... guess we'll see....

    Thanks again,

    EndUser
    My advice and $3 will buy you nothing more than a tunafish sandwich.

  10. #10
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    you can make it work with the right front derialleur/crankset

    We had a reader have a similar question. You can mix and match SRAM 10 speed road / mountain front shifters/derailleurs, and we confirmed this with SRAM. The thing you have to be careful of is using a mountain front derailleur with a SRAM 2x10 mountain crankset, or a road front derailleur with a road crankset. If you want to go top-pull, this would require a SRAM mountain crankset to get it to work "as designed" because as you mentioned, the front derailleurs do move a different amount for each mm of cable pull. Of course you could experiment to see if a Shimano 2x10 crankset would work but SRAM does not endorse this obviously.

    More on top pull front derailleurs in a cyclocross application is here.

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