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Discussion Starter · #1 ·
My Eagle its starting to give me some headaches as in the latest weeks I have spent more time adjusting than riding.

I have 142 rear with a GX drivetrain that used to work pretty good until recently.
Wear chain measured with Parktool gauge is between 0.25 and 0.5.
I did a disassembly of the rear derailleur because the drive-train was getting noisy, cleaned and lubed the jockeys but I can make it shut-up to run quietly anymore.

I can make it shift pretty well(not as smooth as before) but biggest concern is no-matter what I do the chain has a repetitive tick or click when backpedaling, especially on the 10t.
I've realigned the jockey as per SRAM recommendations a little towards the outside of the smallest cog but it still clicks.

At a certain point it seems that that chain goes on top of a tooth of the 10T for a bit and after that the chain slips onto its normal position thus making that noise.
This is present on the other small cogs but to a less extend than on the 10T, on 10T being most noticeble.
B tension is at ~15mm, I've installed new cable, cleaned derailleur, tried new chain.

Do you guys have any other ideas of what else I could try?
Thanks
 

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Have you checked hanger alignment? Hanger could be off a little or the derailleur cage assy could have a slight twist causing misalignment. This happens a lot with these long cage Eagle derailleurs if you ride in areas where trail debris can get pulled into jockey wheel. I'm on 3rd derailleur and 2nd hanger due to debris 'events' in the last 1.5 years.
 

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Discussion Starter · #3 ·
27.5 and Eagle are not a great combo :)

I did got a twig into the jockeys and the upper one has some scuffs that are not very pretty. I think I will order a pair of jockey wheels for start.

I kinda knew hanger alignment would come up and I would have tried it but I don't have a service close to me so this step will have to wait.

Your replacement history worries me :(

Thanks for help
 

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When forward pedaling, the RD guides the chain onto the cassette. As you saw, there's nothing to guide the chain onto the cassette when back pedaling so the chain can catch on the adjacent cog. Nothing you do the RD will affect the alignment of the upper run of chain where it contacts the cassette.

My advice is to not back pedal. 1/2-3/4 turn of the crank should be all you need to phase pedals.
 

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Make sure you've tried all of things mentioned in this thread:

https://forums.mtbr.com/drivetrain-...st-gear-10th-second-highest-gear-1108281.html

Did you set B-screw with the bike at sag position?

Start with Hanger alignment...it seems like an obvious issue at this point. Buy a tool, you'll use it for the rest of your life.. The website CyclingTips.com did a review of the main options.

Then move to setting the lower limit screw. This is the best technique I've seen, watch from 3:15

It'd be interesting to see a photo of the bike in the 10t cog, taken from directly behind at the level of the cassette
 

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Discussion Starter · #6 ·
@Lone Rager I know that and its not like I'm backpedaling all over but its a sign of things not being great there and as long as I know it was silent or more silent before, in my book something is not alright so I am trying to fix or improve it. Also the transmission its not as smooth as before even if it shifts ok, so I can feel and hear some thing are not right.

@PuddleDuck I know Greg's mechanic, always seems a bit dodgy to me but I ended up using his brake bleed technique before and its good :)
In this video all he is using is common sense, al I have tried.
I don't have the b gap tool but I did what SRAM recommended, 14mm and than added 1mm for sag(the 1 mm is just me). To exclude the b gap adjustment I have tried by going in to less than 10 mm to up to 20 mm but the problems on the smallest cog was still there.
Also tried a boost chainring to improve the chainline for the small cogs and it helps a bit
Uisng the boost chainring(on a 142 rear) doesn't seem to affect the shifting on the big cogs, it shifts ok up to 50t and the chain doesnt drop when i am backpedaling.

My main suspect at the moment is the upper jockey that is looking battered, it has some scuffs in it and after I cleaned it, repacked the bearing with grease and filed down some of the little plastic bits seems a tad better. It had some plastic bits on it similar to what you have on a new tire.

I will take that picture of the rear cassette/derailleur and get back here with it.
 

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Hi adyamg, Thanks for the photo's. From that angle it seems that the bottom of the cage *might* be bent to the outside of the bike.

What brought on the noise and shifting issues? I assume from your first post that it developed slowly? It could be set-up or it could be wear, or it could be a combination of both.

Given that Eagle is VERY sensitive to set-up issues, I have to re-iterate what I said in my original post.
1. confirm that the hanger alignment is spot on. That includes checking that any new hanger is aligned.
2. use SRAM's red tool to set the b-gap to their specs, with the rear suspension sagged

Random thought: how much play is there in the rear mech? Check these two threads to see if they resonate:
https://www.rotorburn.com/forums/index.php?threads/gx-eagle-shitty-shifting-solved.315442/
https://forums.mtbr.com/drivetrain-...nks/xo1-derailleur-bolt-gx-eagle-1102087.html

Really random thought: what condition is your chainring in? Is it damaged in any way and "hanging on" to the chain as the chain tries to release from the teeth??
 

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I have the same problem on my Capra.
In my case the cassette is the culprit.
The previous owner of my bike completely set up the drivetrain wrong.

The L and H-screws, the cable tension and especially the B-screw were pretty off.
And he is even more than 30kg heavier than me and used a 28T chainring.
The drivetrain at the time were only 300km old and I had this clicking and jumping on the smalles 3 cogs.

I put on a new chain and adjusted the drivetrain myself so know I only have this on the smalles 10t cog.
But the 10t cog for sure got a fair beating.

How do I know it's the cassette?
Because if I put on my X01 cassette, or the whole wheel from my other bike the problem is immediately gone.
And if I put on the wrecked GX cassette on my other bike than I have the same issues on my X01 drivetrain.

How do I deal with it?
Nothing! Other than that 10T problem the drivetrain shifts and works fine and cassettes are too expensive.
And I got to admit that this problem isn't really that much of a big deal since if I do need to backpedal for climbing, than it won't be the 10T cog for sure.

Heck! I have a 32T chainring now so even in bike park I never use the 10T cog.
I mostly use it for cruising around.
 

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Discussion Starter · #10 ·
Thanks for the opinions and suggestions guys.

Its not very clear to me when it started or I cant pinpoint a moment where I could say, this is the moment it started to tick/click.
When I disassembled the derailleur and inspected it, no obvious bends are visible.
What is obvious to me is that the upper pulley had some marks and scuffs on it. Including the 2 upper pulley shims(they are correctly installed, flatter shim on the inside) have some scratches on them. Also after tinkering with upper pulley i do think there is a small improvement.
In the picture its the old chaining but I have a new one installed and its the same in the back with both rings.
There is a pretty good amount of play in my GX but its nothing others haven't reported.

Closest service that I know have a derailleur hanger adjustment tool is about 250km away from me but I might get in that area for a mountainbike adventure trip and I think I will take it in for check even thow I am pretty sure the b-gap and hanger are alright but I have seen many reporting bent hanger from new. So to exclude these i will do a b gap and hanger adjustment..

As a side note I think that now that Shimano has launched the cheaper 12sp drivetrains, SRAM might be forced to drop the prices on these rather expensive eagles :)
 

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Looking at photos, your drivetrain looks clean and fairly new. Regarding scuffs/marks on jockey and spacers, I don't think the system is so touchy that this would be the issue but could be wrong. I bought a Park hanger alignment tool for $70 and it showed up at my door. I use it all the time...may want to consider this if a shop is so far away.

My current Eagle der (#3 in the last 1.5 years!) is not long for this world. Like the others debris has caused cage to be twisted. I've gotten pretty good and disassy, straightening it out, aligning hanger, and getting things to shift OK but it's time to move on. I have new 11spd drivetrain with a med cage Shimano der ready for the next failure.
 

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Discussion Starter · #12 ·
Hello,
I think the problem got sorted out ... by chance so thanks for all the suggestions.
Yesterday Ive replaced my wheels and the problem is like ... gone. No more tick, click free backpedaling so I am very happy.

My old Bontrager Duster Elite where a bit tired but no noticeable play in the axles but now that I've got a new pair Easton ARC's everything is smooth again so I am guessing the old hub/freehub were busted! But this Eagle is so sensitive ... dooh.

Cheers
 
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