Struggling to index SRAM AXS

I can’t seem to get my Sram Apex 1x AXS setup to index correctly. It’s a 1x mullet setup on a gravel bike based on an Apex chainset, Apex AXS brifters and an X1 rear mech with 11-50t NX cassette (HG freehub body).

Things i have done are:

• Fully clean and re-fit the whole system
• Align the mech hanger with Park Tool DAG 2.2
• Replace the mech hanger with a new one and align that with the tool as well
• Set the B screw position using the Eagle tool, but also adjusted it outside the recommended position to see if that would help
• Set the micro adjust using the app, none of the positions available gave clean shifting in all gears
• Taken off the cassette and checked all spacers were present between cogs
• Updated the firmware on all components
• Cleaned and lubricated the mech pivot points and spring

I am at a total loss as to what else could be the issue. It either overshifts or undershifts between the cogs depending on which gear it is in, so micro adjusting it one way results in worse shifting in other gears. I have noticed that in one cog the chain catches a tooth on the next cog and there just appears to be hardly any clearance between the gears which i guess is to be expected of 12 speed but how i would rectify this i don’t know. Chainline issue maybe with it being a mullet setup? Fake chain?

My first thought would have been a bent mech? As if you know everything else is okay, i can’t really see much else that could be wrong.

We have had a few MTB AXS mechs that have bent, and then the shifting is never great.

Just a small thought, you’ve never had a front mech connected within the system?
Thats confused many people we’ve dealt with, and you just need to re-pair the system to ‘forget’ the front mech.

Set the micro adjust using the app, none of the positions available gave clean shifting in all gears

I had similar issues with a GX AXS mech last year, it would shift through all gears when the chain was fitted but at least a couple would be shifting up and back down when pedalling no matter what I did with the micro adjust on the app. After removing the chain it was obvious that the mech was only going to 10th gear when set to 31 on the micro adjust, it was replaced on warranty in the end. The replacement mech shifts perfectly set at 16 on the micro adjust

All new kit, or used? I find GX AXS goes to shit with worn top jockey bearings, and the older the chain, the worse it is.

It sounds like you have been thorough.

Id check the chain ring for being true as well as the bottom bracket nice and tight.

As above is the chain new and correct (flat top)

Check the smallest cog on the limit screw and check each gear change individually.

It’s done this from new although has 700km on it now. Not sure how i’d approach a warranty claim at this point but will bear that in mind.

Regards correct chain, it came with a flat top chain but i was advised this is not correct due to it being a mullet setup and having a GX mech and NX cassette, maybe this is incorrect afterall though?

It’s done this from new although has 700km on it now. Not sure how i’d approach a warranty claim at this point but will bear that in mind.

Mine had done over 1000km when it was replaced, I’m fairly sure it was faulty when I bought the bike but got gradually worse. I took it back after speaking to a lad from Whyte at a demo day and he said it wasn’t right after around 15 seconds of riding the bike, there was no argument at all from the shop when I took it back. It did take around 7 weeks to get it replaced tho

Interesting, thanks.

I think i’ll see what the shops says then, it’s a Sonder Camino and there’s a local alpkit shop here.

Not sure how i’d approach a warranty claim at this point but will bear that in mind.

warranty might be an approach but you have statutory rights for things to be fit for purpose when you buy them.

t came with a flat top chain

I thought the flat top chain was only for T-Type mechs, have you tried it with a normal chain?

My GX AXS mech is doing the same as yours. I’ve tried everything except a new mech…

Yes I had them replace it with a regular Eagle chain straight away but it’s no better.

Tempted to ditch the system off entirely except the brakes and fit 3×9 with bar end shifters instead ?

Any slop in the parallelogram pivots?

I warrantied 2 XG1275 10-50 cassettes for exactly the same issue. Mine were both bent. I posted about it at the time but you know, the search. I switched to X0 in the end.

Yes there’s slop in the pivots on the parallelogram. From a bit of searching this sounds normal which is disappointing.

My AXS system was a pain to setup but got there eventually. Mine seemed to be very sensitive to chain length and couldnt get it to work with the recommended sram chain length. Mine is running on a normal (non flat) chain.

Have you looked at the bottom of the parallelogram?

4 bolt bolts 6, 3 have bolts in, one empty, but tapped for a bolt

Find a bolt that fits – that may well sort it 

^ yes, that has a bolt in it already thanks. The rest of the pivots are still pretty sloppy though, to be honest. I can move the cage quite far just from the amount of slop.

Aha. If it’s still in warranty, try and get SRAM to replace it, or use the Leap Components bush kit… Should fit the Apex. I used it on a GX mech and it’s cock on now

SRAM AXS Derailleur Bushing Repair Kit

I had problems with Rival on my gravel bike for a while.  Turned out to be movement of the hub and freehub relative to the axle.  Once sorted it was fine.

I know it may not be relevant but I had those symptoms on a mechanical setup and it turned out to be a partially cracked outer plate on the chain.  It was hard to spot as it was cracking around the pin and a bit dirty.

Might just be worth a few minutes.

Have you got the 1.85m spacer behind the cassette? Id that’s applicable on hg one?