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  1. #1
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    Question on cranks

    Does the m8000 1x crank only come with 1 option for a front ring? I am currently running a 2x XT crank and have a single ring mounted outboard (104 bcd). I would like better Chainline, and am curious if the newer xt crank in the 1x option actually moves the front ring closer to the frame?

  2. #2
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    I assume you have a previous model XT 10 speed which was BCD 104/64. The current M8000 XT is 11 speed and is offered in 1x, 2x, and 3x. BCD is now 96/64. The 2x chain line for the prior XT 10 speed and current M8000 XT are the same at 48.8. Because of how chainline is measured for 2x that is the distance to 1/2 way between the 2 rings, so if you run the 2x crank as 1x the actual chainline will measure larger. The M8000 XT has a chainline of 50.4 (measured to the middle of the single ring). Effectively the chainlines will be the same for 1x and 2x run as a single ring; the difference is artifact from how the measurement is taken.

    If you have a narrow/wide or other after-market single ring it won't fit the M8000 assuming you're using the 104 BCD, because the M8000 is 96 BCD. Spending for the M8000 just to change the chainline is not worth it, and won't help. If there are other reasons, of course, that's another matter.

    If your BB shell is threaded 68mm, try moving one of the two spacers from the drive side to the non-drive side. That will move everything over by 2.5 mm. One Up, and others probably, make shims to go between the ring and crankarm you can use to move the ring over. Other companies, Race Face for one, are making single ring cranks that move the chainline over.

    Or, you can keep running it as is. Are you having shifting, grinding or other issues? If not, save your money unless you're looking for a new crankset for the holidays. Make sure to maintain your chain and replace before it's shot.

  3. #3
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    Quote Originally Posted by shortnangry View Post
    I assume you have a previous model XT 10 speed which was BCD 104/64. The current M8000 XT is 11 speed and is offered in 1x, 2x, and 3x. BCD is now 96/64. The 2x chain line for the prior XT 10 speed and current M8000 XT are the same at 48.8. Because of how chainline is measured for 2x that is the distance to 1/2 way between the 2 rings, so if you run the 2x crank as 1x the actual chainline will measure larger. The M8000 XT has a chainline of 50.4 (measured to the middle of the single ring). Effectively the chainlines will be the same for 1x and 2x run as a single ring; the difference is artifact from how the measurement is taken.

    If you have a narrow/wide or other after-market single ring it won't fit the M8000 assuming you're using the 104 BCD, because the M8000 is 96 BCD. Spending for the M8000 just to change the chainline is not worth it, and won't help. If there are other reasons, of course, that's another matter.

    If your BB shell is threaded 68mm, try moving one of the two spacers from the drive side to the non-drive side. That will move everything over by 2.5 mm. One Up, and others probably, make shims to go between the ring and crankarm you can use to move the ring over. Other companies, Race Face for one, are making single ring cranks that move the chainline over.

    Or, you can keep running it as is. Are you having shifting, grinding or other issues? If not, save your money unless you're looking for a new crankset for the holidays. Make sure to maintain your chain and replace before it's shot.
    yes, I currently have a 10 speed xt 104/64. So if I read you correctly, by moving to an M8000 1x crank, my chainline should reduce basically 1/2 the distance between my 104 ring and 64 ring on my 2x crank, correct? Or are you saying the 2x m8000 has the same as the 1x m8000, as far as where the actual ring is mounted? If that is the case, that would help a lot. I am running a 73mm threaded chris king bb, and have moved the one drive side spacer to the non-drive side. I have the 32t oval from absolute black for a front ring, that has a 2mm spacer built into it, and there is no way to shim this ring anymore due to the spacers interfering with the teeth on the ring. I use my 42t a lot, we have steep climbs where I ride. I do suffer from the back pedaling issue, and there is a tad bit of noise in the drivetrain running it on the 42t. Unfortunetly no one makes a 32t oval in 64 bcd, so I can't use my smaller ring.

  4. #4
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    Ok, I think I understand what you are saying, in reality, my current set up, lets say the front 104 bcd ring is 2" offset from center of my frame, and the current m8000 1x the single ring is exactly the same distance away, 2", correct? That is crazy how chainline is measured, how confusing to someone who is not that educated in the sport, and frustrating as hell!

  5. #5
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    Yup, beware of chainline measurements because 1x, 2x, and 3x are measured differently. The XT 1x and 2x, when run as 1x, will effectively have the same chainline. You won't be able to run your oval ring on the M8000 XT because I assume the ring is 104 BCD.

    I assume you're using an add-on 42t cog behind a 10spd cassette. That may be why you're having some issues. That combined with the oval ring, maybe. Have you fiddled with the B screw? The M8000 isn't going to give you a better chainline. I'm not even certain your issue is chainline given that you've already moved everything over by flopping the BB drive side spacer.

    I'd rule out everything else before I spent for a new crankset. If you're still looking at a crankset, I'd then look at Race Face or other spider less crank with a corrected chainline. The M8000 won't change your chainline and won't fit your oval ring.

  6. #6
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    I am running an xt m8000 11x42t, with a m8000 rear derailer. I understand I would need a new front ring, and don't mind replacing it if need be.
    I know my issue is due to the xt 11x42 and the fact they moved the 42t inward towards the spokes, making chainline worst!

  7. #7
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    I'm running the same drivetrain, M8000 cassette and derailleur with 10 speed XT 2x as 1x, but with 32t n/w ring, and haven't had any problems. For what it's worth, and it may not seem like it now, you made a good choice. It may be a problem with chainline, it's always hard to know via online posting, but I'd really check whether it's a B screw adjustment, chain length (sometimes tricky with oval ring or full suspension) or something with the oval ring. I take it you're running an 11 speed chain; is the chain ring compatible? A slightly bent derailleur hanger can also cause weirdness.

  8. #8
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    Quote Originally Posted by shortnangry View Post
    I'm running the same drivetrain, M8000 cassette and derailleur with 10 speed XT 2x as 1x, but with 32t n/w ring, and haven't had any problems. For what it's worth, and it may not seem like it now, you made a good choice. It may be a problem with chainline, it's always hard to know via online posting, but I'd really check whether it's a B screw adjustment, chain length (sometimes tricky with oval ring or full suspension) or something with the oval ring. I take it you're running an 11 speed chain; is the chain ring compatible? A slightly bent derailleur hanger can also cause weirdness.
    Brand new chain, brand new frame and hanger. I tired a KMC 11 speed chain, and it was bad, switching to a sram 11 speed chain helped a lot, I can get 1 full pedal revolution before it jumps off.

  9. #9
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    You could run a 30t on the 64 bcd position and have a very nice chainline.

  10. #10
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    Quote Originally Posted by J.B. Weld View Post
    You could run a 30t on the 64 bcd position and have a very nice chainline.
    I know, it's just I would hate to give up my oval.

  11. #11
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    I wasn't aware they didn't make the oval in a 30t. As mentioned you could get a little narrower if you went with a direct mount crankset, I've heard good things about Garbaruk rings with variable chainline (depending on ring size).

  12. #12
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    Quote Originally Posted by J.B. Weld View Post
    I wasn't aware they didn't make the oval in a 30t. As mentioned you could get a little narrower if you went with a direct mount crankset, I've heard good things about Garbaruk rings with variable chainline (depending on ring size).
    Yea, I think I'm going to stop stressing over it. Straight chain puts the chain on the rear cassette at the 6th sprocket, damn smack in the middle of the cassette. Maybe once the chain wears a bit it will settle in. I can get 1 full back pedal without it shifting down. This is what happens this time of the year with loss of bike rides during the week, too much time on the forums stressing over minor stuff, LOL.

  13. #13
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    Quote Originally Posted by J.B. Weld View Post
    I wasn't aware they didn't make the oval in a 30t. As mentioned you could get a little narrower if you went with a direct mount crankset, I've heard good things about Garbaruk rings with variable chainline (depending on ring size).
    Addressed to you JB since you always have the straight scope on things, and don't mean to poach in on the OP, but since I have an xt m8000 1x crank waiting in the wings wondering what I'm going to be up against chainline wise on my future setup. Interesting that the chain lines is the same in 1x/2x mode. How is that achieved? Offset changes with the ring design on 2x?

    Thanks in advance
    Wait whuuut, who did he tell you that!?!?....

  14. #14
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    Quote Originally Posted by JMac47 View Post
    Addressed to you JB since you always have the straight scope on things, and don't mean to poach in on the OP, but since I have an xt m8000 1x crank waiting in the wings wondering what I'm going to be up against chainline wise on my future setup. Interesting that the chain lines is the same in 1x/2x mode. How is that achieved? Offset changes with the ring design on 2x?

    Thanks in advance
    I'm no authority on them but as mentioned chainline on the 1x is 50.4mm, not great IMO. The chainlines aren't identical for the 1x and 2x models, the 2x is 48.8 (measured between the rings) so that should put the outer ring closer to 51mm.

  15. #15
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    The chainline of the XT M8000 1x is effectively the same as the XT 2x if the 2x is run as a single ring with the ring in outer position. The chainlines of the 1x and 2x are listed as different because the chainline for 1x and 2x are measured differently. The chainline for the 1x is measured to the middle of the single ring. For the 2x it's measured to 1/2 way between the outer and inner rings. Once you run the 2x with only one ring in the outer position the measurement is now pushed outwards. So, the chainlines are different for 1x and 2x but when the 2x is run with a single ring in the outer position the chainlines are effectively the same.

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