Eagle GX 12 spd shifting issue- Mtbr.com
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  1. #1
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    Eagle GX 12 spd shifting issue

    Evening all,

    I have an Intense Tracer that came with a 12 spd GX Eagle 10-50. The bike has no more than 50 hours on it and hasn't been riddin hard at all. "Thats what she said". Couldn't resist, sorry.

    Anyway, I've been running Finish-line dry lube with much success this summer. Recently, I've noticed that the noise in the upper two large cogs is sometimes excessive. The bike shifts fines otherwise. I set the upper and lower limits just like I've seen on every video out there. I set the B gap with my SRAM tool while at proper sag just like instructed. On the stand, the bike is quiet and smooth in every gear except for the two top large cogs SOMETIMES. I say sometimes because if I go up and down with the chain trough the gears, the issue goes away.
    The issue is usually going UP into the 2nd or 1st 50 tooth gear from the third largest. It seems like the chain does not want to fall into the cog teeth all the way and as it leaves the derailleur from the bottom heading up to the cogs it sometimes rides on top of the cog teeth (NOT aligned). As the chain gets to the top of the cog(12 o'clock) it then seems to fall into the cog teeth. Sometimes when pedaling in the second to largest cog, the chain just rides along on top of the teeth, not aligned. If I shift down and back and forth, it goes away and everything meshes just fine on all gears. At the upper and lower limit, the derailleur lines up just fine. No bent derailleur either or the hanger. I checked chain stretch with my park tool, its perfect. No stretch at all.

    One more thing I've noticed, pedaling backwards in the those larger cogs is never smooth. Chain alot of the times wants to jump down.

    I am at a loss for what the heck is going on. Any suggestions are more than welcome.

    Thanks

    Sid
    Last edited by cityjackit; 1 Week Ago at 05:29 PM. Reason: Spelling

  2. #2
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    backpeddling and having chain fall off, is normal on larger chainrings, on smaller chainrings they run a bit smoother.

    the shifting issue is hard to diagnose and it sounds like a cable issue, from what i can tell derailleur is not stopping in same spot on 2 largest cogs.

    so these derailleurs have an issue on some where the pivot bolt has excessive play, and it can be checked if you wiggle the cage and wheels and see if there is slop in said bolt

  3. #3
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    From everything you said if it were me at this point I would remove the cable from the derailleur bolt and start from scratch with cable proper tension and indexing. Only takes a few minutes and can be the culprit of many shifting issues. Park tools has tutorials if you need help.

    If you haven't done this in the 50 hours or so since riding the bike from new then I feel even more confident this might be the problem. Cable housings and ferrules settle into place and change the tension on the cable. That's why the LBS always tells you to come back after a month or two or three for a tune-up. That's really what they're doing.(among other simple things)

  4. #4
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    Its not uncommon for the chain to ride this way in the stand. But work properly when at sag.

    Shifting tension on the cable is meaningless.

    You have a clutch on the derailleur that sets chain tension and it has a spring that pulls the tension on the cable.

    The barrel adjuster on the shifter sets the final position of the shift.

    Find your straightest chainline gear and sight the position of the derailleur. It should sit dead center and there should be no tick or chain catching on a tooth. Adjust the barrel until its dead center.

    If your not shifting perfectly from there, the hanger is bent or you have a kinked inner cable and it needs to be replaced.

    This should cover almost all cases of this issue.

    Chain length must be right and so must b gap.

  5. #5
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    Eagle GX 12 spd shifting issue

    Hereís link to the manual, itís better than video. I have had same issue.
    Fixed it in 15 minutes this past weekend .

    Hereís the story;
    Your index shifter has 12 positions on it, the starting point is set by how you set the high cog (smallest one) .
    It does matter, if you donít set it as shown, then all the shifts will be slightly off. It does not matter except the lowest gears, the biggest ones.
    They will act up.

    Read the manual, un-screw your cable bolt, follow the steps, and reset it all.



    Then, when you test it, I ride on grass with brakes slightly - itís like uphill - applied while shifting, and one click cw or ccw to dial in the last big gears.
    Itís in the manual , see below




    https://www.sram.com/globalassets/do...erailleurs.pdf

    My ride;



    Sent from my iPhone using Tapatalk

  6. #6
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    LBS vs MTBR

    Evening guys,

    Thank you a ton for your guys' input. But now I have even more questions.
    Before I read all what you guys wrote, I spoke to my LBS who are pretty good people and mechanics. Or at least in my rookie MTB life, I think they are good mechanics.
    I described to the owner exactly what I described to you all and he knew exactly what I was talking about. He described it to a T. He said he sees this on the SX, NX, and sometimes the GX, but never on the X1 or X01 or whatever the two upper end SRAM sets are. He said he only sees it while on the stand, and never experiences anything while riding. Thats my story as well. He told me he even mentioned it to his SRAM rep and they said they've heard about this more than a few times and will pass it on to SRAM. For what ever thats worth.

    Now I went to the SRAM owners manual for my Eagle GX 12spd. I had the manual saved in my docs. already, but thanks for the link.
    I do have a 12 spd for starters and I do have what I thought was the correct B gap tool from SRAM. But their manual says the one I have, its for the 1X11, 1X10, and the 1X7. It says I should be using the 1X12 tool. The one on the top left in the attached pic. Every video I watch on how to set the B gap always shows the middle purple or magenta tool that I have. Never have I seen the 1X12 tool. Am I screwing up my B gap adjustment? Also, the instructions from SRAM say to be in the 2nd largest cog, NOT the largest or lowest gear. Again, every video I watch says to be in the largest cog.
    I do not know where to begin now. Wrong tool? Wrong gear for setting the gap?

    FUSE6F... Are you saying to set the limits correctly first with the barrel adjuster one turn out, THEN go to the gear that provides the straightest chainline and make sure everything is good there as far as noise and chatter? Adjust out any chatter or chain jumping with the barrel adjuster only? I like this method.

    Again, not sure if I'm using the correct B gap tool.

    Thoughts on the LBS' comments? See attached pics of manual.

    Thanks

    Sid
    Attached Thumbnails Attached Thumbnails Eagle GX 12 spd shifting issue-0729201943.jpg  

    Eagle GX 12 spd shifting issue-0729201944.jpg  


  7. #7
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    I donít have that gage, so set it via this method with chain on.




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  8. #8
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    Manual?

    Hey mtbdudeX,

    Where did you get that 1X12 14mm gap from? Which manual? The SRAM manual I have says 3mm when on the 2nd to largest cog and then it says 14mm on the largest cog, but only for 1X11.

    Confused, I am.

  9. #9
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    Eagle GX 12 spd shifting issue

    Hereís file I downloaded from SRAM site a few months back
    Uploaded via tapatalk so you can download it
    http://cloud.tapatalk.com/s/5f23098f...erailleurs.pdf

    Sent from my iPhone using Tapatalk

  10. #10
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    Just put the chain on the largest cog, and measure 15mm from cog to derailleur jockey wheel.

    it says 14 but its better to be a hair higher then lower, my bike is set to 15 and shifts perfect.

    the red 12s sram tool will set it to that range

    the shimano derailleur is set to what 46mm from center bolt of jockey wheel to 50 or 52 cog on an eagle GX cassette [similar gap as sram]

  11. #11
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    Thats what I'll do then. Thanks again guys.

    Have a good weekend.

    sid

  12. #12
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    B gap is an independant setting

    You can set the inboard limit too far and catch the chain in the spoke
    You can set the inboard limit too short and the shifter actually doesnt have room to move and even click into the lowest gear.

    Inboard and outboard settings dont change how the shifter works. Only sets the limits for a safe shift. Proof is the fact that you set them before even mounting the cable to the derailleur.

    So do that first.

    Mount up the cable like the video says.

    Now set b gap with the red tool in the 50 tooth. It actually has the teeth outlines on the tool so when the jockey wheel is rotated into position. Everything lines up. Repeat. Everything. You can rotate the tool slightly and be off a tooth. It really does line up perfect in the correct position.

    You must sit on the bike at sag.

    I actually have a helper deflate shock then apply gradual weight onto the seat to get to sag. Then hold. I did my bikes like this but laying on the floor with the late day sun lighting things up perfectly.

    Finally. Who knows how many turns on the barrel. The video says where to start. But thats depends on how you snugged it up. So you shift to a straight chainline and sight the jockey wheel. Its fairly easy to see if its dead center. Look at the edges of the chain against the other cogs.

    a tighter cable pulls the jockey wheel towards the easy gears. So turning the barrel to make it extend from the shifter will tighten the cable and pull the jockey that direction. Do it on purpose and look at the chain edges to see how they move out of alignment from the two adjacent cogs.

    At that point things should shift pretty good. If they are massively off at either end of the cassette then something is bent.

    Make your shifts in the stand and verify it goes up and down with no hesitation Either direction. Make a slight adjustment on the barrel to Perfect the shifts.

    Expect a little wear in on a new housing and cable. As i found on mine last week. It will need a slight adjustment to tighten the cable after a few hours riding.

    I made sure my hanger was straight before starting. Which means top bottom and back edge of the wheel exactly the same distance.

  13. #13
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    To clarify, the chain is not engaging the top two cogs completely on the cassette?

    I've had this happen with X01, primarily due to the chain being stretched too far. Shifting quality, cable tension and adjustments were all fine in my case. Replacing the chain fixed the issue, along with the chainsuck that I was getting with the Absolute Black chainring.

  14. #14
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    Dang, I couldn't ask for better help. Clear cut Fuse, thanks. Heading downstairs to get it ready for tomorrow 7am. Frckin hot as heck here in NC. Gotta get it done all before 10am.

    WRC....I have a new ParkTool chain measuring tool. I cannot even get the .5 to start in the chain. The chain is perfect. I spoke to SRAM, they told me that the chain riding on top of the two largest cogs while ON the stand is normal and due to only a single shift ramp on each cog. Whatever that means.

    Have a great weekend guys and I'll report back this weekend.

    Thanks again.

    Sid

  15. #15
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    Have fun.

    actually might be 4 in the 50

  16. #16
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    Good luck Sid with dialing in your shifting, truly. Nothing more frustrating than on a ride and that happens, ugh.


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  17. #17
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    Well Fuse and MTBdude, ride was awesome this morning. Little muddy, but shifting was like butter. Quiet. Quick, up and down, and best of all........NO NOISE. Honestly, I think the straight chainline trick when adjusting the barrel helped. Went back over the gap adjustment like you both said last night. B gap was spot on.

    I have my old bike back. Now if I can keep my bike straight while doing those huge 2 ft high jumps I'm trying. More or less pushing into the face and when I rebound up and out, I always go to the right side. Just got to keep trying. For now, I'll stay away from the jump line.

    Have a great weekend guys and thanks so much.

    Sid

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