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  1. #1
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    Shimano CS-M770 11-34 strange problem

    Hi everyone, i just bought this cassete, CS-M770 11-34, my last cassete was a Sram PG950 11-32.
    The chain is a Shimano CN7701 (XTR), the shifters and derailleurs are Sram X7, now the problem is when i'm riding on road, nothing happens, the drivetrain is just smooth, everything works just fine, when on trail, sand, dirt and so after 1 or 2 miles the cassete just starts to make a horrible noise like grinding, and i can feel on the cranks that grindind, but only on the 3rd and 4th cog, especially on those 2 cogs, it seems whenever dirt sticks on the chain there is no space for the chain to run smooth, i've tried everything, unmount cassete, mount it again, more torque on the lockring, less torque, but the problem still there, another strange thing is that after a few miles, 4 or 5, the noise go away, can anyone help me?

  2. #2
    Fat-tired Roadie
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    Did you tune your rear derailleur when you put on the new cassette?

    How's your derailleur hanger?
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  3. #3
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    Yes i did, i've adjusted b-screw, and some minor adjustments on H screw, and L screw.
    My derailleur hanger?What do you mean?
    It's normal, not bended or nothing like that.

  4. #4
    Fat-tired Roadie
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    What about your barrel adjusters? There's no guarantee that the cassette will land at the same distance from center when you switch brands. That adjustment is sensitive enough to get screwed up by a small change.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  5. #5
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    Hello, my Sram X7 rear derailleur doesn't have the barrel adjustment, only on the shifter, if i tune the barrel on the shifter like Shimano says, leaving the chain on the second cog and adjust anti-clockwise until the chain make some noise or tries to jump to third cog and then turn the adjustment clockwise until the noise stops, it shifts fine but on the lower gears it doesn't shift well, if i tune the derailleur without chain on the smalest cog, and then put the chain also makes noise, the strange thing is on the road no noise at all, everything runs smooth, on trail with dust, sand and so the noise is there, but after a few miles the noise goes away the same way it started.
    i'm going crazy with this.
    Today the noise was also on other cogs, not only on third (15T) and fourth (17T), but those two are the worse, especially the third one, it look like clicks and crackles, grinding, but on road 32 miles no noise at all, everything smooth.

  6. #6
    Fat-tired Roadie
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    The instructions for tuning the barrel adjuster are a good starting point, but they're not really the best way to keep a rear derailleur in tune, IME.

    When you're riding the bike, if you notice you have trouble shifting to a smaller cog, turn the barrel adjuster a click inwards. If you're having trouble shifting to a larger cog, go the other way. That's why they put them on the shifters.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  7. #7
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    Maybe the hub/cassette/lock ring combination isn't working. Several years back, there were compatibility problems between a Chris King hub and some of the Shimano cassettes, it took a CK lock ring to make it work. If your lock ring was not clamping the cassette completely and was bottoming out on the threads instead, it could cause the problems you're describing.

    Either that, or it could be squirrels. I hate squirrels.
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  8. #8
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    AndrwSwitch i've tried that, no good, the noise still there, and like i said i have no barrel adjustment on the derailleur itself, i don't know why.
    Dad Man Walking what do you mean " If your lock ring was not clamping the cassette completely and was bottoming out on the threads instead", the wheels are Mavic Crossride Disc 2013, when i install the cassete looking at the last cog (11T) she isn't lined up with the end of the hub, has a 1 or 2mm out of the hub, and the cassette spider has a gap between the freehub splines, if i install the the cassete spider without install the 3 last cogs, and hold the freehub body tight the cassette spider moves, it seems the cassette spider has a larger gap between is body and the splines.
    I had no problems whe i was riding with the Sram PG950 cassette, well only a strange noise when climbing on smaller cogs, like "raac raac".

  9. #9
    Trail Tire TV on blogger
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    1. did you get a new chain with the cassette? (recommended) if using the old chain it's probably worn out and too short now (going from a 32 to a 34 granny needs a longer chain) and you've stretched the derailleur and/or tested the hanger.

    2. don't say the hanger is straight,.. it's not something you can expect by eye and you need to use an alignment tool to check it. Often times a worn cassette/chain won't react as bad to lightly twisted hangers as everything is kinda loose and will flex enough to comp the issue.


    (ps, this post should be in drivetrain section not tools )


    honestly it sounds to me like you might have a bad hub bearing/bushing in the outer section of the free hub...? but noises without actually seeing/working on the bike are near impossible to figure out
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  10. #10
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    The chain is also new, the hanger i have taken it out and put it on a glass surface, i didn't see any bending, but i don't have an aligment tool to check that.
    The bearing i don't think so, the wheels are brand new, and it only makes that noise on trail, on road it runs very smooth, without problem, on trail the noise is there, after a few miles goes away the same way it started.
    Another thing, the pulleys are very worn out, especially the down one, they have 4100 miles, and the X7 body has a slight gap also, the pulleys i can put new ones, but the derailleur is still in warranty.

  11. #11
    Fat-tired Roadie
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    Is there play in your rear derailleur?
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  12. #12
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    I've included a picture of a X-7 like mine only mine is a 9 speed one, and marked where i think there is a little play, without chain, if i move the derailleur like the arrows on the picture, yes there is some play on the derailleur, it's still under warranty.
    Attached Thumbnails Attached Thumbnails Shimano CS-M770 11-34 strange problem-sram-x-7.jpg  


  13. #13
    Fat-tired Roadie
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    So stop screwing around and get a new derailleur. If there's play, you can't tune it to function reliably.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  14. #14
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    But it's not supposed to have a little bit play?
    It's under warranty, i will claim on the store if you think it is the derailleur, but why it only makes noise on trail and not on road?
    And the noise goes away after a few miles.

  15. #15
    Nouveau Retrogrouch SuperModerator
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    Shimano CS-M770 11-34 strange problem

    Quote Originally Posted by Traquina View Post
    Hello, my Sram X7 rear derailleur doesn't have the barrel adjustment, only on the shifter, if i tune the barrel on the shifter like Shimano says, leaving the chain on the second cog and adjust anti-clockwise until the chain make some noise or tries to jump to third cog and then turn the adjustment clockwise until the noise stops, it shifts fine but on the lower gears it doesn't shift well, if i tune the derailleur without chain on the smalest cog, and then put the chain also makes noise, the strange thing is on the road no noise at all, everything runs smooth, on trail with dust, sand and so the noise is there, but after a few miles the noise goes away the same way it started.
    i'm going crazy with this.
    Today the noise was also on other cogs, not only on third (15T) and fourth (17T), but those two are the worse, especially the third one, it look like clicks and crackles, grinding, but on road 32 miles no noise at all, everything smooth.
    Classic symptoms of a misaligned hanger.

    You need to check it on the bike with an alignment tool. Does not matter if it seems "flat" on the table.
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  16. #16
    Fat-tired Roadie
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    Re: Shimano CS-M770 11-34 strange problem

    Quote Originally Posted by Traquina View Post
    But it's not supposed to have a little bit play?
    It's under warranty, i will claim on the store if you think it is the derailleur, but why it only makes noise on trail and not on road?
    And the noise goes away after a few miles.
    There may be some flex. But there shouldn't be any play. At least compare it to a new derailleur or have your shop look at it.

    You keep saying the bike is under warranty - exercise it. If the shop's not too busy and the mechanic doesn't mind taking a little more time, get him to show you what he does to fix it.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  17. #17
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    The shop doesn't fix there, it's big shop with several shops in my country, they send it to a central shop where the bikes are fixed, but this friday i will take her to the shop.
    Shiggy thanks, i will take it to the shop like i said to AndrwSwitch.
    Thanks for all the help, especially to AndrwSwitch for the patience and help.
    I will post the result of the shop fix here.

  18. #18
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    Do you have the special mavic freehub spacer installed behind the cassette.

    Is there any movement on the freehub body as it uses a bush to support the end nearest the center of the wheel. the wear will cause it to wobble creating the issues with indexing which in-turn creates unwanted noise.

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