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Poor shifting: Eagle GX


Andrew Buckley
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I had poor shifting between cogs 7, 8 and 9 on my Eagle GX for a while - thought the cassette must have been damaged at some point. I have now got a new cassette and have exactly the same problem!  I have tried every conceivable adjustment, including the B screw.  I can get the 7, 8 and 9 cogs shifting ok, but then the shifting goes out on cogs 1,2 and 3.

 

Any ideas?  could it be a problem with the derailleur? anyone else with GX have this problem?

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I had poor shifting between cogs 7, 8 and 9 on my Eagle GX for a while - thought the cassette must have been damaged at some point. I have now got a new cassette and have exactly the same problem!  I have tried every conceivable adjustment, including the B screw.  I can get the 7, 8 and 9 cogs shifting ok, but then the shifting goes out on cogs 1,2 and 3.

 

Any ideas?  could it be a problem with the derailleur? anyone else with GX have this problem?

 

 

 

When last have you replaced the outer housing and or the inner cable?

 

How old is the derailleur because the guide wheel at the back of the derailleur can wear a groove in which the cable runs and that changes the pull ratio slightly to affect a few of the gears. 

 

Lastly if you ave checked these it could be a lazy return spring but that is quite rare although often blamed when its just the cable.

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Start by checking the hangar alignment. If you don't have an alignment gauge you could either try and hack something, or just take it to your LBS when they open again.

 

Then adjust the gears from scratch. If the problem persists change the cable and housing and go from there.

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Thanks for the responses.  The hanger looks straight to the naked eye, and I had the cable and housing replaced when I did the cassette.  The derailleur has at least 15000 kms on it so the worn guide wheel sounds like a possibility.

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Had the exact same issue .... one click at a time on the barrel would just move the issue up or down the range ....

 

 

Took it to my LBS.  They confirmed a very slight bend in the hanger.  Straightened it, and all was golden.

 

 

lots of dusty trails later I had issues with the inner-and-outer cable ... it "felt" different.  Almost as if it would not shift up, even though you heard the click. Had to to put a bit of pressure on the lever for it to actually go up .... on the down you had to double down, then nudge it up ....  Not a big issue as this was just before the annual service, so I had the inners and outers replaced.

 

 

Many more trails with almost no issues ..... on some rides I would have to give the barrel 1-click out after about 10km .... then on the way home I would have to undo that one click ....  Apparently this affects some of the GX systems, LBS (various different shops) knows of it, but no real solution ...

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Thanks for the responses.  The hanger looks straight to the naked eye, and I had the cable and housing replaced when I did the cassette.  The derailleur has at least 15000 kms on it so the worn guide wheel sounds like a possibility.

 

Unfortunately, straight to the naked eye, doesn't necessarily mean it's straight.

Also, check your B indexing screw. If this is not setup correctly, it has a massive impact on shifting due to the distance of the top pulley from the cassette, as well as effects the chain wrap, resulting in more or less "chain binding" when you are wanting to shift

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Thanks for the responses.  The hanger looks straight to the naked eye, and I had the cable and housing replaced when I did the cassette.  The derailleur has at least 15000 kms on it so the worn guide wheel sounds like a possibility.

 

Straight to the naked eye won't cut it for a hanger on a 12sp setup, it need so to be done with a tool.

 

That said, bent hangers usually present as bad shifting on one end of the cassette and not the other, and you can generally change which end doesn't work with a half turn of the adjuster barrel.

 

Start by checking chain length. A chain that's too long will shift badly even if the B gap is correct. Run the chain around the chainring and 50T, bypassing the derailleur, and shorten the chain to a 2 link overlap (2 full links, ie. 2 sets of an inner and outer plate). If it's a full sus, check this at the point of maximum chain growth.

 

Next up, B screw. Use the tool. If you don't have the tool, the gap between the 50T and the top pulley is 14mm. Check this at the sag point if you can. While you're there, check the pulleys for play - if there's play in the bearing your shifting will suck.

 

As per D&D's suggestion, take the cable pulley off and check for wear. If it's worn, Bikeyoke make a CNC replacement with a bearing called a Shifty, which will improve your life a bit less than the price tag would suggest. But it's cheaper than a new derailleur, and it'll outlast the derailleur so you can move it to the next one you buy when you get to that point.

 

If you're still having issues after all of this, change your inner cable - it may have a kink in it somewhere. It happens.

Edited by droo
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Had the exact same issue .... one click at a time on the barrel would just move the issue up or down the range ....

 

 

Took it to my LBS. They confirmed a very slight bend in the hanger. Straightened it, and all was golden.

 

 

lots of dusty trails later I had issues with the inner-and-outer cable ... it "felt" different. Almost as if it would not shift up, even though you heard the click. Had to to put a bit of pressure on the lever for it to actually go up .... on the down you had to double down, then nudge it up .... Not a big issue as this was just before the annual service, so I had the inners and outers replaced.

 

 

Many more trails with almost no issues ..... on some rides I would have to give the barrel 1-click out after about 10km .... then on the way home I would have to undo that one click .... Apparently this affects some of the GX systems, LBS (various different shops) knows of it, but no real solution ...

We don't give this guy credit enough for the detailed and informative responses he gives. Even if it's to the same question time and time again. Cheers!

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Start by checking chain length. A chain that's too long will shift badly even if the B gap is correct. Run the chain around the chainring and 50T, and shorten the chain to a 2 link overlap (2 full links, ie. 2 sets of an inner and outer plate). If it's a full sus, check this at the point of maximum chain growth.

 

Thanks Droo - do you mean run it around the chainring and 50T but not through the derailleur?

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I'm going to agree with Andrew here.  

My only caveat would be that SRAM Eagle is notorious for the B tension alignment issue going out.  So Occam's razor approach would be to establish that the height is correct first.  Even if the others are out and you correct them, If the b tension is out you will still be having issues both up or down.  So my process would be:

 

Measure and adjust (if necessary ) the B tension screw to establish the correct height 

Then remove derailleur and check the hanger alignment with Hangar Gauge and adjust if necessary (or replace hangar)

 

THEN I'd run through the gears using my hand to push the derailleur and (not the shifting ) to isolate the cable and it's potential friction issue.  I'd do this to check the range it gets and to see if the limit screws need adjusting and to see if the return spring (where the derailleur returns down to the hardest gear) is still allowing the derailleur to return nicely. If this seems fine, I will go ahead and starting using the shifter and see what the result is. 

If I'm having lazy shifts to the easy gears, I will adjust cable tension higher (a little bit at a time) and retest from the bottom up again. I repeat the process until I have crisp shifting, then if I have crisp shifting to the easy gears, I will test the done shift (to the harder gears) if this is lazy after all that, it means the cable friction is to difficult for the derailleur return spring to over come, so I then know that replacing the housing and cable is the reason.

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