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  1. #1
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    2012 Shimano XT chainring options?

    Hello Everyone,

    I'm planning on upgrading the drivetrain on my 2012 Trek Marlin (29er). I've been interested in the 2x10 Shimano XT group, and was really interested in the SRAM XX1 1x11 group until I saw the expected retail price for it (yikes!). So now I'm back on the Shimano train

    I'm planning to wait for the new XT 24-38 crankset option to be released when I buy the group.

    Anyways, my question is, are there different chainring options that I can use, without breaking the "Dyna-sys" functionality? Like 34t, 36t.
    Are there Shimano options? or stirctly have to look at 3rd party (I've been reading references to "Blackspire")
    And if there are options, is it easy to change the chainring? (like how XX1 allows to change without having to remove the crank arm)

    Thanks and I appreciate the advice,

    foujin

  2. #2
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    There are VERY few official options - from what I can find the Shim XT DynaSys comes with three supported chainring sets

    3x 24/32/42
    2x 26/38
    2x 28/40

    I have a 3x crank, and I have successfully used the 2x parts and made a 28/38 combo. It's a little high geared for me right now though so I'm trying to figure out a way to make a 24/36 or 24/38 combo work out. I like the high gear range with the 38t ring, but need the lower range a 24- or 26- would give me (I have some painful steep extended climbs in some of my rides).

    You may get some other options using M980 XTR rings (the M980 crank uses 64/104 BCD), but be advised that the rings have a different mount profile, I assume the crank spider is significantly different.

    For example the XTR DynaSys 26t ring offsets the teeth ~2.5 mm in-board. I tried one out on my bike and had to use a couple spacers between the crank and BB to shift it over. I also had to add chain-ring spacers between the middle ring (38t) and the spider to close the gap. It was a finicky setup but did mostly work. I'm not sure I like needing the chainring spacers though.

    FYI,
    I have tried other granny's with the 38t ring and the front shifting s**ks b**ls in that case.

    Using a non-ramped middle ring with the dyna-sys chain is just unhappy. I think the outer link plate sculpting really gets in the way. It's a theory anyway.

    On my bikes for the previous 10 years I've run 2x9 with DH rings in the middle position and had no problem up-shifting from granny with 24/36 so this really surprised and frustrated me. I am probably abandoning the dynasys chain the next time I need a replacement ... or this weekend ... depends how frustrated I get with it.

  3. #3
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    Quote Originally Posted by bear View Post
    On my bikes for the previous 10 years I've run 2x9 with DH rings in the middle position and had no problem up-shifting from granny with 24/36 so this really surprised and frustrated me. I am probably abandoning the dynasys chain the next time I need a replacement ... or this weekend ... depends how frustrated I get with it.
    Thats the opposite of what I've done on doubles. Normally I run a straight cut steel granny with a ramped/pinned middle ring/big ring. Ramps and pins help a lot with shifting speed and precision.

  4. #4
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    Quote Originally Posted by GTscoob View Post
    Thats the opposite of what I've done on doubles. Normally I run a straight cut steel granny with a ramped/pinned middle ring/big ring. Ramps and pins help a lot with shifting speed and precision.
    They do, but they also increase chain suck potential in adverse conditions. Previous drivetrains haven't had a problem shifting - just not quite as lightning quick as the fancy rings - never just sat there with the chain hitting both rings though like the stupid dynasys one does.

    Ramped/pinned also tend to wear faster - but I'm willing to give RaceFace and Blackspire rings a go, they've treated me well in the past. I have a RaceFace Turbine 10s ring coming. ;^) If that one doesn't work out in the long run maybe I'll try one of the XTR middle rings - carbon-reinforced titanium. $$$ but maybe it'll work and be worth it by providing long life.

  5. #5
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    The Dyna-Sys shifting is really, really good. I'd try and stick with one of the combos that Bear mentions above. 26x36 is a very low-gear. But if you are thinking of going lower, I'd ask do you ever out-run a 32x11 gear? If the answer is no and you want to be sure of enough low-end, just go w the 24/32.

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    Thanks for the replies guys,

    I'll wait for the official release of the XT 2x10, 24-38 chainring combo (LBS says end of August it should be available for order). The new 2013 SLX already has the 2x10 24-38 combo (available now), but figured I'd just wait for XT to come out with that.

    I think I should be able to handle the 38t ring, as it's mostly flat, with short climbs here. I just wanted a "backup" plan to a 36t if it was too hard.

  7. #7
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    I think the Shimano combinations are sorely lacking in options, myself.

    I've tried and gotten equivalent shifting performance from the RaceFace Turbine ring, and with RaceFace you have more options.

    Also, there's nothing magical about the rear shifting, the SRAM 1031 on my bike now shift just-as-if-not-better than the dynasys chain it replaced on the same cassette.

    I'll probably use a pretty KMC next since it has a reusable quick-link.
    Last edited by bear; 08-13-2012 at 03:00 AM.

  8. #8
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    My Setup...

    I just bought an 2012 XT-Triple crank (FC-M780) and it came with 24/32/42 rings. I swapped out the 24t for a RF 22t, the 32t for a Blackspire 32t, and the 42t for a RF bash. I'm running a 10-sp XT cassette, a KMC 10sp chain, a SRAM X9 RD, and a 2008 XTR FD - and it all shifts perfectly together!

    Bottom-line... don't let Shimano corporate dictate your riding life! Get what works for you!
    "The secret of joy is the mastery of pain." (Anaïs Nin)

  9. #9
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    Hey Foujin and Bear,
    I've been searching through the threads as I have been having an issue which relates to the above.
    For a good few years I have been riding my 5 spot with double and bash 2x9 with 36t and 22t rings. This has worked flawlessly and only with the onset of 10 speed equipment have I chosen to change it.
    So here's the thing, 10 speed sram x9 rear der. and shifters, SLX 9 speed front mech and an xtr 10 speed chain with XT cassette 11-36 all running on 38t and 24t rings (the 24 being xtr and the 38 being a gamut single ring, no pins and things).
    Again all worked no problem until my front mech took a hit.
    So I replaced with the new XT 10 speed front mech, will this work?
    Will it hell.
    So conclusion is the 10 speed dynasis chainrings are only compatible with the new front mech's and as such you will need to run an older 9 speed double specific mech to enable smooth operation on anything else. At first I thought the chainring ratios were too wide but shimano assure a max 14t drop which this is bang on.
    So as you have already said waiting for the new xt 38t,24t double chainset seems to be a winner..... or simply wait for the chainrings to be available and retro fit to any compatible cranks to have perfect shifting and compatibility with dynasis 10 speed front mechs.
    38, 24 is a great combo too!

    Rick
    God....whatever i feel like doing!!!

  10. #10
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    Is there any harm in going with a SRAM x9 3x10 crankset with a Shimano Dynasys triple system? My bike came with a crappy OEM crankset and I prefer the gear range of SRAM cranks (22x33x44) over Shimano XT (24x32x42).

  11. #11
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    Shimano definitely wants you to run the entire "system" no question.

    I may try the 24/38 next spring when things start drying out again, but for now my 24/36 works great. The additional 2t just is not a big win for me considering how finicky my setup has to be (direct mount low type front d).


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  12. #12
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    I've been running one of the new 24/38 XT doubles and a shadow plus RD for a month now, and its the best shifting I've ever experienced! And that's coming from a doubter, who was hanging onto his 2x9 SLX drivetrain for as long as possible!

    But, I'd agree, the newer Shimano stuff isn't so forgiving of the mix-n-match approach. I used to run SRAM cassettes and KMC chains on my old setup, but have gone full Shimano for this one - but when it all works so well together, why not!

  13. #13
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    FAIL: mix & match XT chainring experiment failed, now time to fix it

    I tried 22 chainring from XT 3x10 on my 2x10 swearing I'd not use the small ring with the big cogs in the back until I got a good 34 or 36t replacement for the outer chainring so I could shorten the chain.

    But on my last ride I had a FD ghost shift and shifted down in the back and sucked my chain into the RD cage and snapped the XT M785 shadow+ RD in 1/2.

    (for details see the my post " Beware of the 14t limit: Don't add a 22t chainring to Shimano XT 26x38 2x10" on the "Shimano XT FC-M785 Crankset 38X26T - 24t possible?" thread.

    I have a few questions: has anyone sourced a good 36 or 34t front chainring REPLACMENT that will fit & work with my XT cranks to swap out the 38t and keep in the 22t?

    If I do finally get a outer chain ring with 36 or 34 teeth, which XT rear derailleur would be most appropriate, long cage or medium?

    Finally, I'm considering a e13 TRS+ dual chain guide when I get everything else dialed in. DO you feel it adds protection beyond a shadow+ rear mech once I fix the front cranks to no longer disobey the 14t rule!


    Thanks!

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