12 Speed SRAM Derailleur and Cassette Compatibility Issues

harringtonp

Bought a bike with a SRAM Rival eTap AXS XPLR Max 44T derailleur which came with a SRAM Rival, 12-speed, 10x44 cassette. Electronic shifting, works perfectly.

Bought a second wheelset and fit a SRAM XG1250 Rival AXS 12s/10-30t cassette. While shifting in the 6 smaller cogs works fine, the behaviour when shifting into the larger ones is erratic:

• When coming down it won't go into the second largest, click again and it skips it going direct to the 3rd largest
• Slow shifting to larger cogs on the 6 biggest cogs while shifting to larger on the 6 smaller ones is snappy
• Usually won't go into the largest cog

From https://support.sram.com/hc/en-us/articles/6042447056539-What-size-cassettes-work-with-the-XPLR-rear-derailleur- I see

While the XPLR rear derailleur was designed for use with the 12-speed 10-44T cassette, it will work with 12-speed 10-36T cassettes as well. The chain length and b-gap distance will be different between cassettes- be sure to check out the user manual for full installation instructions that are specific to your gearing choice.

SRAM XPLR drivetrain parts are compatible with existing 1x 12-speed road cranksets, 1x 12-speed chainrings, and Flattop 12-speed chains. The XPLR rear derailleur works with 12-speed 10-36T and 10-44T 12-speed cassettes.

This sounds like they are saying they only support 2 cassettes. Anyone any idea what is going on ? I would have assumed that once the spacing between the cogs is standard and the derailleur supports the max cog size there should be no issues.

harringtonp

10-44 Teeth: 10,11,13,15,17,19,21,24,28,32,38,44

10-30 Teeth: 10,11,12,13,14,15,17,19,21,24,27,30

jayjbe

https://www.boards.ie/discussion/comment/120454968#Comment_120454968

It's the b gap. This needs to be finetuned per cassette size. There's a red plastic tool you can get to set it. Simple enough to use and should make switching between different cassette sizes fast. Especially once you get the number of turns on b gap screw.

Trekker09

https://www.boards.ie/discussion/comment/120455910#Comment_120455910

https://www.google.com/search?q=b+gap+sram+axs&oq=b+gap&aqs=chrome.6.69i57j0i512l9.13961j0j7&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:8ae494ed,vid:fO9FuZroc8E

harringtonp

Thanks guys but I strongly suspect that the derailleur above only works well with the 10-36 and 10-44 as mentioned in the linked blurb. If I had a 10-36 cassette it sounds like the above tuning with the red plastic tool would work. But I suspect that with the 10-30 no amount of b gap tuning would get smooth shifting. Would this sound right ?

I wonder would a second shorter chain work ?

The intention of the above setup was that I could switch a gravel bike between gravel and road use quickly by just changing wheelsets. Apart from the shifting issues the road wheelset works great. In hindsight I should have bought a second 10-44 cassette but didn't see the point of the larger cogs when using in road mode.