Hey folks.

I’m running a mashup of SRAM AXS on a shimano cassette and chain. Mainly as I got microspline wheels and cassettes aren’t cheap.

I’m currently running the 45T shimano cassette but due to lack of fitness I’ve tried putting the 51T cassette on with a new chain.

It was running really nice on the 45T but I can’t get it to shift nice on the 51T…..any suggestions?

Shift nice at all or just to the 51t. Have you changed the settings in the AXS app at all? MicroShift for example.

Longer chain?

Check that the dearailuer upper pulley is not too close to the 51 tooth cog, you might need to alter the b screw to give it enough clearance to move the chain onto the 51t cog.

It shifts nice in the lower set of the cassette (smaller cogs) but it struggles with the larger cogs. I’ll get a longer chain and try that.

Which mech is it?

You will also need to adjust the b-gap as well.

It’s a SRAM XX1 Eagle AXS 12-Speed Rear Derailleur

I have this on my ebike, once I had the b-tension right it shifts fine.

It’s a SRAM XX1 Eagle AXS 12-Speed Rear Derailleur

Should “just work” then. Move the cog out further with the b screw. Also… was it a new chain on the new cassette?

Check the b-gap.  I’ve got GX Axs running just fine on a 10-51 SLX cassette and Shimano chain.

Thanks guys. I’ve got it running apart from In the largest cog it every so often one link doesn’t line up and it jumps a little.

It’s a brand new cassette..

And a new chain?

Yeah brand new chain

Thanks guys. I’ve got it running apart from In the largest cog it every so often one link doesn’t line up and it jumps a little.

in the stand or when riding?

In the stand. I’ll get a video

It seems the same tooth the entire time. I’ve marked it with green pen

Shimano chain?

Yeah Shimano chain

I thought only newer Eagle stuff worked with 50+ stuff? OG Eagle was only 50, is the mech compat with 51 or 52? I have an older AXS X01 and I dont think it is.

Good point that. ⬆️

Yeah I just looked at my spec of mech and it says max 50T.

I thought all the AXS stuff was 52t compatible?

After doing some digging it looks like all AXS is 52T compatible and it’s the mechanical series that was limited. I have done a video which should be in the link below

I’m running SRAM GX AXS Derailleur & shifter with Shimano SLX chain, chainring & 51T cassette. Had it on my Rise for over a year

Key things for me were b-gap from tooth tip of 51T to centre of top pulley = 45mm

And swapping out the SRAM pulley/jockey wheels for Shimano XT M8100 ones (£17) as the GX AXS ones don’t play nice with the Shimano 12spd chain width

YMMV

I can hear a rubbing noise just before the chain doesn’t engage. What’s that? Rotor? Is the cassette mounted OK?

Are the jockey/Pulley teeth fully engaging with the chain?

in the stand or when riding?

>> In the stand.

Does it do it when riding? Sounds a bit like @oceanskipper’s recent thread where there just wasn’t enough tension on the chain to extend it fully in the stand – worked fine IRL.

Actually my issue was the narrow wide profile on the teeth of the largest two cogs needs some chain tension in order to “catch” properly. Shimano cassette doesn’t have a narrow wide on it. Still, it could be a chain tension issue and needs testing under load, get someone to hold the brake lever if it’s hard to tell when riding…

I reckon that noise in the video has something to do with it though…

I’ve had a play about this morning and it appears it was mech hanger alignment. All is running good now so thanks guys