I’ve been running a XX1 setup (XO1 cassette) for a bit over 18 months now. Given the cost of the cass. I’ve been pretty paranoid about chain wear and they’ve been replaced as soon as they hit 0.75%

I stuck a new chain on 3 rides ago. The first ride it worked fine, both the other 2 (one FILTHY ride, today very clean), it’s been doing something strange in the 42T. It feels like its attempting to shift up under power. It’s not the sudden “giving way” feeling of the chain slipping on the cassette, and if I carry on pedalling, I carry on going forwards, and it’s only ever a single “snick”/lurch, as if the chain drops onto a smaller cog then climbs back up onto the 42T again.

The 42 sprocket does look considerably more worn than the others, but if I try and pull the chain away from the sprocket it moves very little.

All gear cabling was brand new yesterday, and it’s shifting perfectly. Limit screws & B screw haven’t been touched since I fitted the setup.

The only times it was playing up today was on steep technical stuff, and I never actually managed see what was going on, and being intermittent I could never anticipate when it was going to happen either.

Any ideas, before I splash a load of cash on a replacement 42T sprocket? I’m almost wondering if its the chain line causing something weird when the chain comes off the short teeth on the sprocket that make it shift easier…

Cheers,

Jon

Tight link perhaps?

I would have thought that would have manifested itself all the time in every gear?

Worn 42t ring.

The 42f ring is alloy. Material specs from SRAM :

MATERIAL 4130 chromoly steel (cog cluster), AL-7075-T6 (largest cog)

I’d suggest you put a smaller ring up front so get a better chain line and wear on the steel rings. 42t ring should be just for the odd steep climb. I’m on 4th chain, change about 0.9 plus. No issues, 42t ring like new. Centre rings showing lots of wear

If it turns out to be worn Wolf Tooth components do replacement alloy 42t for the XO1/XX1 cassettes.

My xo1 cassette is now on its 4th chain changed around 0.75-0.9 no problems so far, only thing I do find is when it’s really muddy and clogged up it can feel clicky but it doesn’t skip rings.

Check for bent teeth and any FO jammed in them on the big cog? If it “climbs up” once a rev, that can be the cause??