So, been running a full X01 12 Speed Eagle Group set for 4 months on a new long travel bike with Boost chain line (3mm offset chainring) and the shifting has been getting gradually worse to the point of distraction.
I’ve checked the usual suspects I.E. mech hanger, limit screws, B-Screw, chain wear etc and I’ve replaced the cable and played around with the cable tension, all to no avail. I can get it so it will shift nicely up the whole cassette but the mech pulls and ticks on the second to highest cog, so rotate the barrel adjuster on the shifter to get rid of the tick and then it won’t shift down. Even if you leave it with the tick it’s still not great at shifting down through the middle of cassette. The cable is shifting nicely through the outer both forwards and backwards when it’s detached from the mech so no problems with the shifter or line of the outer. It’s similar symptoms to a sticky or frozen mech or mech cable but the cable and mech is moving fine and the chain just won’t drop properly.

I’m thinking of trying a few other ideas, maybe a 6mm offset ring, an 11 speed chain and eventually a new mech just to rule a fault out, but talking to a few other riders they seem to be having similar issues. Just wondering what other people are experiencing and if there is a miracle cure ?

Cheers

Did you use the SRAM template/spacer to set the b-tension? My eagle was exactly the same as I didn’t have one of those but took it into my LBS who did and it was sorted immediately. Does seem super sensitive to b-tension.

I’m pretty sure my Boost-hubbed Eagle 12 speed set up came with a 6mm offset chainring.

…mech pulls and ticks on the second to highest cog…

Yea mine has done that since day one. X01 Eagle Mech & XX1 Eagle Cassette on Hope Boost Hub. LBS couldn’t fix it either and it was all setup with the red tool.

Friend had the same problem and his gear cable had a kink in it, replaced it and it solved the problem, but I can see you tried that.

Yep, used the template thingy and I’ve tried running with both both more and less b tension. First on the basis that more B screw would make the chain hug the cassette more and stop the ticking and then with less on the basis that it would stop the holding on to the chain and let it go (please!). Made no difference at all.

Press fit BB, boost cranks and boost hubs… Eagle boost chainring with 3mm offset. The Sram guide says it should be a 3mm offset too but might give the 6mm a try, again just to rule it out.

X01 Eagle Mech & XX1 Eagle Cassette on Hope Boost Hub

Same setup as this. I thought cable routing might be a factor and I’ve loosened all the grommets on the entry and exit ports for the internal routing so as to make sure the cable can move freely back and forth. You can get it set up and working well in the stand then when you ride it out it’s crap again, so obviously the cable length and tension under compression is a factor…. but it’s a mountain bike FFS so shouldn’t do that !!!!

I’m pretty sure my Boost-hubbed Eagle 12 speed set up came with a 6mm offset chainring.

Sorry about the 20 questions post… but what chainring is everyone using with a boost hub and crank set 3 or 6mm offset ?

3mm

Sounds like its the jockey wheel.
Check how much wobble is on the upper one

Boost is 3mm offset

I had something similar on XO1 11 speed. LBs could get it set up but it wouldn’t last long. Found out just before I sold the bike that one of the jockey wheels was back to front. Took it out, swapped it round and it was perfect. It was like that from new.

My XO1 eagle on current bike has now done 900 miles and doesn’t even need a chain yet. Had the gear cable replaced last week as I was having the bike serviced anyway but the chain and cassette are still way within tolerances, and shifting still as crisp as new.

Thanks nicolaisam and julzm, thought I had a eureka moment there and checked the jockey wheels but they’re all fine and the correct way round.

Out the box for the first few months it’s all been fine but getting gradually worse. Something is making the cassette hold onto the chain and its not the cable or screw settings.

As you said something is making the cassette hold onto chain ..

Ok I’ll say it “wear” 😥

Ok I’ll say it “wear”

There’s no stretch on the chain at all and no wobble in the mech bolt or bearings. The chain ring looks a bit worn but I can’t see it being that already. Others seem to be getting a lot more miles out of their group set than I’ve done.

I’ll be testing a replacement mech (I’ve got a spare I’ve bought for a trip away) and then I’ll try a new ring.

Definitely not wear, mine has done this since day 1. I’ve now got used to holding my thumb on the lever to stop it trying to shift.

I had the exact same problem as you, but the shop still hasn’t been able to fix it. In addition, my chain rides on top of the sprocket teeth instead of fully meshing with them in the two largest cogs (42-50). Can you check if yours does this too ?

I have a thread going on about it on MTBR.

Paul

So, just had another fiddle and got some results…

Despite the chain showing no wear at all on the gauge I tried changing
it and it immediately eliminated the pull on the rear mech. I then decided (well actually had it decided for me because I **** up a link when shortening the chain) to try running the chain with 1 less link, and that also made things a bit better in the stand once I’d gauged the b-screw again, but as soon as I took it out on the road it was a bag of shite again. So watching the action in compression I figured I needed to run the chain tighter by adding more b-screw, once I’d done that I released the cable and set it up again with 1.5 turns in the barrel adjuster.

In summary, the chain appears to wear out very quickly and the b-screw needs winding in more to compensate for the compression in the suspension.

Sram advise setting up the B-screw with the shock in its sag position for best results.

I had the exact same problem as you, but the shop still hasn’t been able to fix it. In addition, my chain rides on top of the sprocket teeth instead of fully meshing with them in the two largest cogs (42-50). Can you check if yours does this too ?

The issue is that the teeth are effectively narrow wide on the top two cogs, so unless you hit the right teeth/chain combo it won’t sit properly on the ring. The shifting ramps are located in the right place to guide the chain onto the right teeth, but this requires just the right amount of b tension to work. I would recommend:

Let the air out of your shock and compress to 40% sag, then zip tie the shock in that position. You tend to be using those cogs when your climbing, and so the shock is squatting down a little more than sagged at static, so 40% is about right.

Either zip tie or elastic band your rear brake half on so that the wheel turns but has plenty of resistance, this mimics the load on the chain when pedalling uphill.

Set the gears up while rotating the cranks slowly (the brake being half should mean thats the case anyway).

Doing these things means you get a real life set up, rather than a workstand set up which should help alot. It won’t deal with worn chains and the like, but its better out of the box than the standard set it up at 0% compression, no chain load and winding the cranks like there’s no tomorrow.

I did take sag into consideration when adjusting it by removing air and using a strap to hold it down. What do you mean by

Set the gears up while rotating the cranks slowly (the brake being half should mean thats the case anyway).

I went to a shop in the United States and the mechanic called SRAM directly (not possible in Canada); they were aware of the problem and apparently there was a production issue with one batch of cassettes. SRAM sent a new one to the shop so I should know in a few days…

The speed the chain is moving and the load on the chain when shifting will dictate how fast it shifts, you could set the b tension and find your hitting the right cog teeth on the work stand, but under load be hitting the wrong one. By applying the brake and pedalling slowly you replicate the on trail load and speed on the chain, giving you a better chance of finding the right b tension you need. Assuming you’re running you rear brake on the right though no need to strap the brake down, just pull the brake while shifting.

I was a little less scientific about it when I set it up on Saturday after changing the chain.

I set up so it was running perfectly in the stand then took the bike out, leaned on it heavily to see how much the mech moved under load then adjusted the b-screw by that amount…it meant the line on the red gauge was just about visible at the bottom of the tooth pattern when it was back in the stand.

Tested on Sunday on the trail and it’s all alot better and shifting fine but I’ve still got a slight annoying tick on the second cog from the top on the climbs. Maybe I’ll go back and try the faff of letting air out the shock and applying the brake etc. Thanks for the tips benpinnick.

There’s no stretch on the chain at all

4 months and no stretch? What chain tool are you using? I replace my SRAM 11 speed chains at .5 wear, as at .7 they wear the rings too much to mesh well with a new chain.

I’m assuming that Eagle will be worse.

I set up out the box, to the video, full compression of shock for chain growth, tool for B tension etc and had issues with it between the largest ring and the next one down.

then watched video again and picked up and asked myself why they use the mech hanger tool first. Found out though when I put a new hanger on and it worked spot on and has for 8 months.

I’m guessing the more gears on the rear is giving the chain and the clearances involved between it starting to engage/ride up to the next gear a lot less free space and therefore you need everything to be spot on or it will start to ride up or down.

I made a few discoveries about Eagle when I installed a new chain last night. I started a new thread on MTBR :

http://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/sram-eagle-design-flaw-1052658.html

sram’s manufacturing processes are shite

it’s more of a flawed design. N/W on a cassette ?? How can that possibly work all the time ?