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  1. #1
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    XT M8000 moves chain when pedaling backwards on lowest gear. Any suggestions?

    This happens on the largest cog. I'm a born again beginner, so I'm not sure if this is common. When I brought it to the bike shop where I bought the bike, the mechanic said it's just how this bike and gear set was. It's not a huge deal, but kind of annoying when I'm moving the bike around indoors and washing the chain.

    I'm guessing it doesn't matter, but it's a...
    2016 Giant Anthem - 1x11 - All XT components

    Thanks in advance!

  2. #2
    NedwannaB
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    Do you mean when you backpedal when in biggest cog on cassette(granny) the chain drops down to the next cog?
    Wait whuuut, who did he tell you that!?!?....

  3. #3
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    I have a 1x11 Sram and that happens to me too. Its has to do with the chainline. If you can figure out where the absolute straight chainline cog is, you can try to figure out a different shim stack up on your bottom bracket to move the chainline towards your biggest cog. Be careful though because if you do do that then your crank moves in and has a potential to hit you chainstay. Or your shoes may hit as well.

    The good news is when your riding there not really a need to pedal backwards especially when your at your largest cog. I back pedal when I'm pointing down for foot placement but typically you're not bombing downhill on your largest.

    Kind of a crappy answer but there's not much you can do about this...
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  4. #4
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    Quote Originally Posted by JMac47 View Post
    Do you mean when you backpedal when in biggest cog on cassette(granny) the chain drops down to the next cog?
    sometimes it drops down two cogs, but yes, that's what it does.

  5. #5
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    Quote Originally Posted by Junersun View Post
    I have a 1x11 Sram and that happens to me too. Its has to do with the chainline. If you can figure out where the absolute straight chainline cog is, you can try to figure out a different shim stack up on your bottom bracket to move the chainline towards your biggest cog. Be careful though because if you do do that then your crank moves in and has a potential to hit you chainstay. Or your shoes may hit as well.

    The good news is when your riding there not really a need to pedal backwards especially when your at your largest cog. I back pedal when I'm pointing down for foot placement but typically you're not bombing downhill on your largest.

    Kind of a crappy answer but there's not much you can do about this...
    I figured the mechanic knew what he was talking about, but I just wanted to double check with you guys. Thanks!

  6. #6
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    I just installed a m8000 1x11 cassette on my WFO, and it does this as well, only when on the 42t sprocket. I chalked it up to chainline, glad to hear others are experiencing this as well, and I assume it's a non issue on the trail.

  7. #7
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    It only becomes a issue if you stall out on a climb or have to ratchet your cranks to pop over an obstacle while in the 42t. Some rides it'll never happen, but when it does its very hard on the chain and cassette.

    IMO a 50mm chainline is terrible if you're in the lower part of the cassette often. The increased inwards offset of the XT 11s cassette just makes the chainline that much worse.

  8. #8
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    There has to be a fix to this issue, it's rather annoying on my ride today.

  9. #9
    ups and downs
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    How fresh are the 1x11 drivetrains? 2x10 was bad for this when the chain was new but it became less of a problem once the chain has a few hours on it and was bit flexier sideways
    I'm a member of NSMBA and IMBA Canada

  10. #10
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    KMC chain has 1 ride on it. I have heard some have had better luck on sram chains.

  11. #11
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    well, I moved the bb spacer to the non-drive side, didn't help. I then installed a sram chain, and that helped a lot, I can get 3 full back pedals before it jumps off the 42t, and I am very happy with that!

  12. #12
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    Quote Originally Posted by jdaigneault View Post
    well, I moved the bb spacer to the non-drive side, didn't help. I then installed a sram chain, and that helped a lot, I can get 3 full back pedals before it jumps off the 42t, and I am very happy with that!
    There is something wrong with the set up of your derailleur. Limit screw or B or something bent. M-8000 works perfectly fine with 1140 or 1142, and certainly works fine with Shimano chains (why would the chain make a difference?!). It actually works great with 1145 with which I never had a problem backpedaling or otherwise.

  13. #13
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    Quote Originally Posted by Davide View Post
    There is something wrong with the set up of your derailleur. Limit screw or B or something bent. M-8000 works perfectly fine with 1140 or 1142, and certainly works fine with Shimano chains (why would the chain make a difference?!). It actually works great with 1145 with which I never had a problem backpedaling or otherwise.
    This is a brand new derailer, I think it may have more to do with frame geo - chain stay length. The b screw adjustment or the high low adjustment made no difference.

  14. #14
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    Just in case anyone else has this issue, I found a solution for it on my bike, which didn't have any room on the BB spindle for any spacers. I simply got some chainring spacers and put them on the crankarm side of the chainring. I tried a few different sizes: 3.5, 4.3, and 5mm. All helped, but 5mm ended up being the best in terms of moving the chainline in for a smoother spin on the largest cogs without having any noticeable effect on the spin on the smallest cogs.

    The only issue with this fix is that I ended up needing to buy longer chainring bolts (stock is about 10-11mm, and I ended up getting 17mm, though I think 15-16mm would be fine).

    Maybe the chain loosening up would help this eventually, but I was getting some serious grinding when the chain got some grit in it. Sounded awful. This created a huge improvement.
    Last edited by sgniwder99; 12-12-2015 at 04:51 PM. Reason: proofread

  15. #15
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    its a chainline/chainstay issue. it happens on my yelli screamy, m8000 42t, 1x ab oval 32t. i don't mind... i don't think anyone will back pedal on low gear... ie, why bother?
    Canfield Yelli Screamy

  16. #16
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    Quote Originally Posted by spyghost View Post
    its a chainline/chainstay issue.
    Yes, well established already in about 4 posts in the thread, and

    Quote Originally Posted by spyghost View Post
    i don't mind... ie, why bother?
    Congratulations on not minding. Some people do. Someone in the thread requested a fix, so I posted an easy one.

    Have a nice day.

  17. #17
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    You can try a cassette spacer on the freehub to move the cassette outboard a little too.
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  18. #18
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    I don't think it's a chainline issue. I'm using a ring with a 49mm chain-line on a Boost bike, so my chain-line should be really good.

    I mean, maybe it is chain-line related, but it shouldn't happen at standard spacing, let alone inboard spacing.

    Everything was new from the beginning, and it hasn't changed since.

    Kinda annoying when you're sessioning tech climbs or have to ratchet.
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  19. #19
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    I have m8000 on one bike and m7000 on another. The m7000 does not drop when pedaled backwards in biggest cog but the m8000 does. Same chain rings on both bikes same cassette ratio also. 30x11/40. What I noticed is the 8000 cassette is ramped differently than the 7000. The 8000 has three teeth in three places along the cassette that are cut away on non drive side on the largest cog. I would assume this is so when you shift up to the largest cog it can grab the chain and cause it to shift up. The 7000 cassette is ramped similarly except the teeth are not as aggressively cut away. When I back pedal the 8000 cassette it always drops the chain at the same place on the cassette, right where the teeth are cut.

  20. #20
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    it's not an issue guys, if you take a good look at your bike and think about why the chain is actually moving when shifting gears it's pretty obvious this behaviour is normal

  21. #21
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    Kind of interesting...I have a 2016 Mojo HD3 with boost and had the problem where when I peddled backwards on the M8000 42 cog the chain would drop. Went through 3 chains with this cassette same thing no matter what. Moving forward to this week 1100 miles time to change the cassette, new M8000 cassette 42 Cog has some different chamfers on it...problem is gone...can peddle backwards without chain drop.

  22. #22
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    Ok, I had the same problem with m8000.

    Tried messing with the limit screws etc and never got anywhere, chain also sounded rough in the larger gears on the cassette.

    Took it apart and noticed that my adjustable rear drop outs were not perfectly even. They were out by a couple of mm on one side resulting in the wheel being 3-4mm out where the wheel went through the stays (rough measurements). I adjusted so they were exactly the same distance (micrometer), tightened everything up and now the chains runs backwards on the stand no problem, got to wait to ride again and will post once ride checked.

    Also if your using a shimano chain, some of them are not symmetrical so check on the installation instructions which way round they need to be installed.

    My two cents.

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