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  1. #1
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    Is new XT double crank (M785) 88bcd?

    Does the new XT double crankset have the same 88bcd bolt pattern as the XTR double?

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    Thanks. I was confused because in the photos the spider portion of the cranks looks different between the double and the triple. Are they actually different?
    Attached Thumbnails Attached Thumbnails Is new XT double crank (M785) 88bcd?-xt-double.jpg  

    Is new XT double crank (M785) 88bcd?-xt-triple.jpg  


  4. #4
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    Yes the 2x10 cranks are different from the 3x10s. They are a dedicated 2x10 crank, unlike the 26/38 XTR crank which is the triple with the inner and middle positions used.

    The nice thing about the XT 2x10 is that it will have a 48.8mm chain line so you don't need to worry about the fit of the cranks like you do with 26/38 XTR cranks.

    http://spokemagazine.com/2011/04/14/...onent-line-up/

  5. #5
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    So, since the XT 2x10 26/38 crank has a 104/64 pattern, then I could put a 22 or 24T small ring on it, right?

    I want a 2x10, but a want a lower granny than a 26T. I could just remove the large ring from a triple (or replace it with a bashguard), but if I can put a smaller ring on the double then I should have a more optimal chainline for 2x10. Do I have this right?

  6. #6
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    Quote Originally Posted by jabrabu View Post
    So, since the XT 2x10 26/38 crank has a 104/64 pattern, then I could put a 22 or 24T small ring on it, right?

    I want a 2x10, but a want a lower granny than a 26T. I could just remove the large ring from a triple (or replace it with a bashguard), but if I can put a smaller ring on the double then I should have a more optimal chainline for 2x10. Do I have this right?
    Yes that is correct. Any 64 BCD chain ring should fit. Now how it shifts could be a different story. If you get too big of a spread between the chain ring sizes you can run into shifting issues. Best thing to do is to test it, especially if you already have a 22T from another crankset.

  7. #7
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    Quote Originally Posted by jhymel View Post
    Yes that is correct. Any 64 BCD chain ring should fit. Now how it shifts could be a different story. If you get too big of a spread between the chain ring sizes you can run into shifting issues. Best thing to do is to test it, especially if you already have a 22T from another crankset.
    Yeah, what I want is the 2 inner rings from the triple on the double crank arms, so I'd have a 24/32 or a 22/32 with a better chainline and better appearance than if I just removed the big ring from a triple crankset.

    I had a 22/33/bash on another bike (29er), and I liked the gearing for the trails I ride. It shifted great with a 2x10 front derailleur, so the triple vs. double crank arms is splitting hairs, but I might as well go with the more optimal chainline if I can.

    Shimano calls the 26/38 a "trail" double, but for a whole lot of people a 26T isn't a low enough gear for hilly trails, especially on a 29er. I guess they figure those folks should just buy the triple crankset.

  8. #8
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    Quote Originally Posted by jhymel View Post
    Nope its the 104/64 pattern.
    Which is SOOOOO much better.

    SRAM wants to take our low gears away with stupid bigger BCD's on the 2x10 set ups. Very stupid. Especially with the 29er boom.

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    Quote Originally Posted by smilinsteve View Post
    Which is SOOOOO much better.

    SRAM wants to take our low gears away with stupid bigger BCD's on the 2x10 set ups. Very stupid. Especially with the 29er boom.
    The workaround for this is to use one of their triples and get rid of the big chainring. The Stumpjumper FSR Expert 29er comes with the triple X.0 crankset with the big chainring replaced by a bashguard, creating a 22/33/bash. Although chainline might not be theoretically optimum for a 2x10 setup, the front shifting was excellent and I didn't notice any chainline issues.
    Attached Thumbnails Attached Thumbnails Is new XT double crank (M785) 88bcd?-stumpy%2520cranks.jpg  


  10. #10
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    Quote Originally Posted by jabrabu View Post
    The workaround for this is to use one of their triples and get rid of the big chainring. The Stumpjumper FSR Expert 29er comes with the triple X.0 crankset with the big chainring replaced by a bashguard, creating a 22/33/bash. Although chainline might not be theoretically optimum for a 2x10 setup, the front shifting was excellent and I didn't notice any chainline issues.
    YES! I have a buddy with a lot of money but not a lot of bike knowledge I've been telling to do that exact thing. He is buying a high end Tall Boy and the shop is telling him to go with the SRAM 2x10 because "that's what everyone is going to now". There is no upside in my mind to the 2 speed cranks, and a giant downside. Although the shop says the 2 plus bash won't shift as well, that is really minor and trivial in my mind.
    If you live in the flatter parts of the country, which many people do, then you probably have no issues with the new 2x cranks, but with a 29er, in Colorado, for an older guy, low gears are key.
    I have a feeling SRAM will realize the mistake and change their BCD's, which will really piss of the people who buy this first go at 2x10.

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    Quote Originally Posted by jabrabu View Post
    The workaround for this is to use one of their triples and get rid of the big chainring. The Stumpjumper FSR Expert 29er comes with the triple X.0 crankset with the big chainring replaced by a bashguard, creating a 22/33/bash. Although chainline might not be theoretically optimum for a 2x10 setup, the front shifting was excellent and I didn't notice any chainline issues.
    The chainline of the 2X cranks and triples with the outer ring removed are STILL further outboard of the "proper" 45mm chainline for the cassette.

    Current mtb crank chainlines are about tire and FD clearance, not ideal alignment with the cassette.
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  12. #12
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    Quote Originally Posted by smilinsteve View Post
    I have a feeling SRAM will realize the mistake and change their BCD's, which will really piss of the people who buy this first go at 2x10.
    What timing Steve! According to this article SRAM will be releasing a line of 2x10 cranks with "All Mountain" gearing on what appears to be a traditional 64/104 spider bolted to the same crankarms. Gearing will be 22/36 and 24/38. The racier 2x10 gearing doesn't appear to be going anywhere as a lot of people do like it or even prefer it, but they're providing more options now. The article even says the spider and rings will be available as an "upgrade" kit without having to but a whole new crankset

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    Quote Originally Posted by boomn View Post
    What timing Steve! According to this article SRAM will be releasing a line of 2x10 cranks with "All Mountain" gearing on what appears to be a traditional 64/104 spider bolted to the same crankarms. Gearing will be 22/36 and 24/38. The racier 2x10 gearing doesn't appear to be going anywhere as a lot of people do like it or even prefer it, but they're providing more options now. The article even says the spider and rings will be available as an "upgrade" kit without having to but a whole new crankset
    Funny! I knew it! Taking away low gears just smelled rotten from the first time I heard it. Plus, I think SRAM wasn't thinking of 29ers when they came up with the idea. They figured a 26 small on the front was small enough if you make up for it with a 36 in the back, and that would work for a lot of people especially on 26ers, but for 29ers that still doesn't put you close to the equivalent of the standard 22x32 of a 26er. 22x36 on 29er= 22x32 on 26er.

    Thanks for the link.

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    Another article about the new all mountain chainrings here:
    http://www.spoke.ie/2011/04/sram-int...-x0-in-silver/

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    Quote Originally Posted by jabrabu View Post
    Another article about the new all mountain chainrings here:
    http://www.spoke.ie/2011/04/sram-int...-x0-in-silver/
    thanks, I guess i missed that announcement the first time because apparently it's old news.

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    Quote Originally Posted by boomn View Post
    thanks, I guess i missed that announcement the first time because apparently it's old news.
    I missed it too. After seeing your post above I did a search and found it. I'm glad to find this out because it looks like the perfect choice for my next bike build. Unfortunately, from another thread here it sounds like it won't be available until mid-September.

    It's also nice to see that it will be available as a spider/chainring upgrade. I could just get an X.0 triple in the meantime and upgrade to the 22/36 double later.

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    Maybe I'm computing something wrong, but if you are going to use a 22 or 24 teeth granny ring I think that removing the big ring from a 3x10 will give you a better chainline than a 2x10 crank.

    The 3x10 XT has a 50mm chainline measured from the middle chainring. Removing the big ring moves the chainline between the granny and the middle at 47.5mm, which is closer to the 45mm ideal than the 48.8mm offered by the 2x10 XT crankset.

    As a drawback of course you'll have less clearance for a larger granny rings though.

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    Quote Originally Posted by smilinsteve View Post
    Funny! I knew it! Taking away low gears just smelled rotten from the first time I heard it. Plus, I think SRAM wasn't thinking of 29ers when they came up with the idea. They figured a 26 small on the front was small enough if you make up for it with a 36 in the back, and that would work for a lot of people especially on 26ers, but for 29ers that still doesn't put you close to the equivalent of the standard 22x32 of a 26er. 22x36 on 29er= 22x32 on 26er.

    Thanks for the link.
    I dont think having a 26T on a 26er works either. I live in Socal and ride some pretty steep techy trails. Sure i can suffer up some of these trails with a 26T, but using a 24T would be much better when paired with the 11-36t cassette.

    I just got my bike (26/38t XT) and i am wondering if anyone has successfully replaced the 26t with a 24t. The 26T is not the right option for the trails i ride on a 30lb AM bike.

  19. #19
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    Quote Originally Posted by Redley78 View Post
    I dont think having a 26T on a 26er works either. I live in Socal and ride some pretty steep techy trails. Sure i can suffer up some of these trails with a 26T, but using a 24T would be much better when paired with the 11-36t cassette.

    I just got my bike (26/38t XT) and i am wondering if anyone has successfully replaced the 26t with a 24t. The 26T is not the right option for the trails i ride on a 30lb AM bike.
    I just realized that i am running a 11-34 cassette with my 26T front ring. Maybe this is why i am having such a problem with steep trails that i used to kill. Ive only ridden the new bike twice, but it has been a PITA.
    Would it be better to solve my dilemma by going with a new cassete 11-36, or by dropping the front ring down to a 24T? (The cheaper option isnt necessarily what im looking for.)

  20. #20
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    Gearing , 3x , 2X, 1X and 29'ers is an issue much discussed in this and the 29'er forum over the past few years, and it really blows my mind that the big companies like Shimano and SRAM are STILL leaving it to small companies to give the public a solution. You've got Anderson Machine which has figured out how to jam a 30T on 104 bcd ranks (but you have to grind your spider) and Middleburn which sells a 5 arm micro drive crank in 94/58 bcd, 20T-30T- 40T, advertised as 29'er specific. With that gearing up front, you don't need 36T cog in back, either 10 speed or modified 9 speed.

    I have a 26'er converted to 650b 1x 9 and bought a 31T ring from Homebrew to put the gearing where it was with a 32T up front on 26", again without having to change the cassette (11-34). I also have a 650b specific trailbike 2x 9 which I run bash- 32T- 22Twith 11-34T cassette. That works fine.

    But if I had a 29'er, no way I would run anything other than 9 speed with the 94/58 bcd crank. How come the big companies can't figure this out?
    Old enough to know better. And old enough not to care. Best age to be.

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    [QUOTE=dwt;9277702]With that gearing up front, you don't need 36T cog in back, either 10 speed or modified 9 speed. QUOTE]

    Uh, yes i do! I dont ride flat XC trails. I can ride my 37lb DH bike up these steep trails with a 24T- 11-34 cassette, much better than i can a 30lb AM rig with a 26T front and 11-34T cassette.

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    Quote Originally Posted by Redley78 View Post
    Uh, yes i do! I dont ride flat XC trails. I can ride my 37lb DH bike up these steep trails with a 24T- 11-34 cassette, much better than i can a 30lb AM rig with a 26T front and 11-34T cassette.
    Respect for riding that bike uphill.

    My 1 x 9 HT is a 24 lbs XC bike, but it goes up steep hills, I promise. With THAT bike weight, I'm geared fine. My trailbike is 5" suspension @ 30lbs. That's about my limit for going uphill and down. I would be lost on a 6" AM bike, either direction. Just being honest.
    Old enough to know better. And old enough not to care. Best age to be.

  23. #23
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    Swap tripple XT cranks for double?

    Quote Originally Posted by frenk View Post
    The 3x10 XT has a 50mm chainline measured from the middle chainring. Removing the big ring moves the chainline between the granny and the middle at 47.5mm, which is closer to the 45mm ideal than the 48.8mm offered by the 2x10 XT crankset.
    I'm trying to figure out wether to swap the M780 tripple for the M785 double. I dont see how removing a ring affects the chainline. The closer chainline on the M785 seems like a main reason to switch cranksets vs just removing the big ring.

    I also see mixed messages on wether one needs to 2x10 specific front derailleur if you switch to the M785 double. I know you don't need to swap out the front shifter as it has 2x10 or 3x10 option (i'm guessing to compensate for the chainline of the M785 crankset).

    I'd love to hear from anyone who really knows the answers. Speculation is not helpful.

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    Quote Originally Posted by jkidde View Post
    I'm trying to figure out wether to swap the M780 tripple for the M785 double. I dont see how removing a ring affects the chainline. The closer chainline on the M785 seems like a main reason to switch cranksets vs just removing the big ri
    Actually you get a worse chainline with the 785 than the triple with big ring removed (both being further out than the ideal chainline). That's because the goal of the 785 is to allow larger rings that would hit the chainstay/FD on the triple crank.

  25. #25
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    With a 2x10 crank, does running small/small & big/big still an issue? Meaning those gear combos should not be run.

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