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  1. #1
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    2 x 10 drivetrain weight vs. 3 x 9 drivetrain weight

    Until discussing the topic with a riding buddy of mine last evening, I was under the impression that the new SRAM & Shimano 2 x 10 XX/XTR drivetrains (shifters, crankset, chain, cassette) are lighter than the pre-existing 3 x 9 XO/XTR drivetrains. That's when I realized (duh) that taking a cog away from the front and adding one to the back, cancels out most weight savings. This true??

    A primary reason I would consider in a drivetrain "update" is to shave weight. Otherwise, the change- for me -would be a solution to an issue I don't have.
    It's not dirt in my apartment --it's Earth.

  2. #2
    Hike it or Bike it!
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    Quote Originally Posted by awai04
    Until discussing the topic with a riding buddy of mine last evening, I was under the impression that the new SRAM & Shimano 2 x 10 XX/XTR drivetrains (shifters, crankset, chain, cassette) are lighter than the pre-existing 3 x 9 XO/XTR drivetrains. That's when I realized (duh) that taking a cog away from the front and adding one to the back, cancels out most weight savings. This true??

    A primary reason I would consider in a drivetrain "update" is to shave weight. Otherwise, the change- for me -would be a solution to an issue I don't have.
    Somebody did a nice write up on their blog with a link here to the weights of the new 2 x 10 XX, X.O and one of the Shimano 2 x 10's as well. And you're right - not that much in savings if at all.

  3. #3
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    but you're taking away a large part and replacing it with a smaller part.
    And if done right...the crank will be a little lighter because it doesn't need the material to mount a 3rd ring.
    Small saving.....but they add up

  4. #4
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    Ah, thanks for the replies. I guess I can wait until I build up another mountain bike from scratch to consider the 2 x 10 drivetrain. Sure, the smaller weight savings add up, but probably not enough to justify the current cost premium over last year's 3 x 9 models. At this point, my wallet may be the more likely component to get lighter with a 2 x 10 drivetrain!
    It's not dirt in my apartment --it's Earth.

  5. #5
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    Weight loss is the wrong reason to go 2x when compared with 3x. The right reasons are:

    Narrower q-factor cranks
    Better front shifting
    Better chainline

    The technology has not changed, just refined to meet 2 chainring needs. Only upgrade if you spend almost no time in granny ring.
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

  6. #6
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    Quote Originally Posted by AlexRandall
    Weight loss is the wrong reason to go 2x when compared with 3x. The right reasons are:

    Narrower q-factor cranks
    Better front shifting
    Better chainline

    The technology has not changed, just refined to meet 2 chainring needs. Only upgrade if you spend almost no time in granny ring.
    The right reason is you don't need the range of 3x. The three reasons above are pretty questionable considering how much benefit is actually delivered. The real question with 2x is whether you choose the wide range, purpose built 2x crankset or you REALLY improve the chainline by converting a 3x crankset with a bash.

  7. #7
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    Quote Originally Posted by awai04
    Ah, thanks for the replies. I guess I can wait until I build up another mountain bike from scratch to consider the 2 x 10 drivetrain. Sure, the smaller weight savings add up, but probably not enough to justify the current cost premium over last year's 3 x 9 models. At this point, my wallet may be the more likely component to get lighter with a 2 x 10 drivetrain!
    You can change to 2X set up on the cheap.
    I'm guessing you have a 9 speed set up now and a 64/104 crank??
    Pick a small chain ring size and buy it in the 64 bolt pattern...and do the same for you Middle ( which will now be your big ring) ring...and buy some shorter bolts for that ring.
    Set your front deraileur stop so it won't shift past the middle.
    Done....and you saved the weight of the big ring...plus have simpler shifting.

  8. #8
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    Quote Originally Posted by the mayor
    You can change to 2X set up on the cheap.
    I'm guessing you have a 9 speed set up now and a 64/104 crank??
    Pick a small chain ring size and buy it in the 64 bolt pattern...and do the same for you Middle ( which will now be your big ring) ring...and buy some shorter bolts for that ring.
    Set your front deraileur stop so it won't shift past the middle.
    Done....and you saved the weight of the big ring...plus have simpler shifting.
    Do it this way and odds are that you will have gearing better suited to your uses and a better chainline than any dedicated 2x crank. It's a win-win.

  9. #9
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    Yeah, thanks guys. I was thinking the same! I may even pick up some of the last generation (& now discounted) XTR cranks to do just that with a 29er project I have in mind.

    Quote Originally Posted by the mayor
    You can change to 2X set up on the cheap.
    I'm guessing you have a 9 speed set up now and a 64/104 crank??
    Pick a small chain ring size and buy it in the 64 bolt pattern...and do the same for you Middle ( which will now be your big ring) ring...and buy some shorter bolts for that ring.
    Set your front deraileur stop so it won't shift past the middle.
    Done....and you saved the weight of the big ring...plus have simpler shifting.
    It's not dirt in my apartment --it's Earth.

  10. #10
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    Its a no-brainer for me...

    ...the shiftng performance of this setup is outstanding compared to the triple.
    Dura-Ace derailleur
    Campy road triple crank with big ring removed
    40 / 28 or 42 / 28 gearing depending on the course.

  11. #11
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    Quote Originally Posted by awai04
    Yeah, thanks guys. I was thinking the same! I may even pick up some of the last generation (& now discounted) XTR cranks to do just that with a 29er project I have in mind.
    I wish the m970s were discounted now, but they seem to hold their value even used. I would even go as far as to say they were cheaper 6 months ago.

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