12sp SRAM indexing woes?

Got a new bike that came with 12sp NX mech and shifter and GX cassette, after a couple of rides it was jumping a bit and then all the time, so stripped everything down, checked it all and tried, for quite a while to get it working, but it did the annoying top 6 work fine, then jumps around the 3rd from bottom, or the bottom 6 work fine and it jumps around the 3rd from top, no matter what i did, it just moved the problem from top to bottom, or vice versa.

After another strip, clean and rebuild i fettled again, finally getting it to work, but confidence is not high it’ll stay that way.

I see to remember this being an issue the last time i had 12 speed SRAM, i’ve lived with 11sp shimano for the last year and a bit and it’s been faultless on two bikes, so this is not increasing my love of SRAM!

Just to narrow it down, things i’ve done to try and fix were: check cable, reset all tolerances on the mech (low/high/b screw and checked the clutch), checked the mech alignment, checked hanger alignment, checked torque on hanger and mech, cleaned all parts of drivetrain, lubricated all parts, checked chain length, checked cable wasn’t snagging, checked hub, freehub and cassette for any issues and probably a few more bits.

This of course is on a bike that’s less than a month old and hasn’t seen rain or mud yet, or been crashed in any way, bar a couple of low speed front wash outs (we’ve all been there with the trails as dusty and loose as they are?!) that were left sided, so drivetrain not going near ground.

Did you check the derailleur hanger with a hanger alignment tool? Are the jockey wheels properly fastened? Cassette lockring done up tight? Is the derailleur cage straight?

Mine does exactly the same, and did since new. Took it back after a week, had a brand new mech fitted FOC under warrenty, worked fine for a ride, now all over the place again. There’s also an alarming amount of play in the mech cage for something with only about 150km in it. Asked a few mechanics, response seems to be ‘it’s Sram, thus it will be shit’. Considering ditching the mech and shifters for 12speed SLX.

i can only say how nice my GX is
check the b tension with the tool
also, don’t suppose there’s any chance you are running the wrong offset chainring or anything?

Check for excessive play in the top jockey wheel.

I’ll save you some time.

Entry level 12sp SRAM stuff is woefully fussy to set up and worse, needs almost constant fiddling to keep it running even “mostly alright” once you’re past the first say, 100/200km of use.

Most GX Eagle sufferers have their own theory on why, it’s the jockey wheels, it’s the B Screw, it’s the B-Bolt, it’s the chain line, it’s the derailleur, it’s the chain, it’s in the inner, it’s the outter etc etc. You need to swap to a XXXXOOX1 shifter, or Derailleur.

I don’t think it’s any of those things, I think it’s a fundamentally flawed product and even though they quietly revised it a few times, it just doesn’t work very well if ANY of the above is slightly worn, because SRAM was more interested in bringing a ‘cheap’ mega-range 12sp 1x system to market before Shimano did.

SRAM recommended you change the chain, cassette, front ring and jockey wheels, seemingly every other time you use it.

Its so fussy about everything. Hanger has to be perfect, mech has to be perfect with no wear, cable has to be perfect. Jockey wheels seize up. Its almost not fit for purpose.

Tweak it on a rock and thats it, it will never work perfectly again.

I’m going Shimano next time I clip the rear mech.

Didn’t know that Shimano and Sram 12 speed was compatible, might go that way myself soon as my 18 month old gx rear mech is doing the same thing and has done it since it was about 12 months old. It’s only really been used when the weather was decent as I have other bikes for the slop.

Shame as I like the shifter action.

After looking at the jockey wheels and they are pretty worn and the mech has a fair bit of sideways movement too.

I’ll try new jockey wheels and see if that works as that’s quite a cheap fix.

Installed XT M8100 12 speed on my Tallboy earlier in year. After doing a fair few Eagle installs, was amazed with how incredibly easy it was to setup and index by comparison. Barely more difficult than 11 speed Shimano, which was already the easiest configuration on the market today.

Highly recommended and I don’t doubt that the SLX and Deore options are also excellent.

Anyone with experience of the superstar components alloy jockey wheels?

Isn’t the sram shimano thing the same as it always has been

Shimano patented indexing with a floating top jockey. Everyone else has to muddle through without that key part.

Frankly I’m relieved that mine isn’t worse than it is after reading this

Anyone with experience of the superstar components alloy jockey wheels?

Yeah they’re beautifully made, bit noisy be work fine…. if it wasn’t for the fact they’ve made both top and bottom narrow-wide and the top have a habit of jumping off, so you end up with it on the wrong tooth making a lot of noise and fuss.

Ordered SLX shifter and mech, will change it over as a 3 ride old mech and shifter being this fiddly doesn’t bode well, at least it made me clean and check over the entire bike, i’ve encountered almost every problem known in over 20 years of biking, but SRAM 12 speed just seems to be something that isn’t suited to me, shame as i hate changing bits that shouldn’t really need changing like this.

Let us know how you get on. 👍

Think P-Jay is right. This stuff just wasn’t ready or tested properly before hitting the market.

Myself and others have had the chain come off the lower jockey wheel and get wedged between the cage and jockey multiple times for no reason. Drivetrtain stops dead, mech bent, no longer shifts properly. They now come with a revised jockey wheel design.

At just over 1000miles I had the chain snap, no the links didn’t pull apart, it snapped. Upon closer inspection it was cracked in 2 other places. I’ve never seen anything like that. This is a chain that’s rated to hold up the weight of a Toyota Prius.

Wear in the jockey bearings and mech rivets results in play that causes poor shifting. Never had a Shimano mech develop play in the rivets.

I believe Shimano still have a lot of the patents on shift ramps so the Sram stuff won’t shift as good anyway.

On the whole, fiddly to set up with slow and clunky shifts.

Going to curse myself now and say that I’ve got GX 12 speed set up on 4 bikes in our house and it’s been fine. Missus damaged a mech when a stick got caught and that’s it in 2 years.

So next week, they’ll all go to shit now and I’ll be starting a thread about the best place to buy Shimano 12 speed 🙂

My hard tail was suffering from slow shifting until I changed the gear cable. Somehow it had managed to kink in the middle (about an inch long) and when the outer hit the kink, the shifting became sloppy.

I’ll keep it on until it potentially goes awol again, but will have the SLX in the background keeping the NX on its toes!

I just have little confidence in that rear mech, the more i look at it and check it over, the less i feel it’s been built to any real tolerance, hopefully i’ll be proved wrong and it stays on for a while, but i just can’t believe something that does a job such as a rear mech has been designed with so much lateral movement through compounding of 3 or 4 areas of the mech.

I has this issue with mine ages ago and so I bought the red plastic tool to set the jockey wheel to cassette distance and it has been fine since.