SRAM AXS question - can I run eagle axs MTB RD w/ axs road cassette?

I’m thinking about building up a gravel bike with SRAM AXS. I’m planning to go 2x with road gearing as the default (fine for most of the gravel racing around here), but there might be situations where I want to run a 10-50 cassette (and switch to a 1x up front) for courses with really steep stuff. I know the 10-50 cassette requires an eagle (MTB) AXS rear derailleur. If I just went with the Eagle RD, can it be used for both the 10-50 MTB and the 10-33 road cassette? Wondering if the spacing is any different? I think I heard you need a spacer or something on the XD mtb vs. XD road drivers or something.

Nope, that won’t work. The older Eagle RDs only work with the 10-50 cassette, officially they cannot even handle the new 10-52 cassette. Newer Eagle RDs accept the 10-50 and 10-52 cassettes. But they do not work with any others.

But you could get a second rear derailleur while you are at it and just change crankset, RD and cassette. :slight_smile:

My understanding is that the Eagle AXS RD’s work with the 10-52, but not the mechanical ones. All the announcements on 10-52 said that Eagle AXS was compatible.

Anyway, I’m more concerned with whether I can run Eagle AXS RD with the road cassettes (10-33). I know the range isn’t an issue, but wondering if there is any spacing differences that might cause issues. I think they might have had to tighten up spacing just a little on the road cassettes because they couldn’t recess the big cog like they did with the 10-50. I thought I read that somewhere and they had to make the chain a little thinner (so I maybe tighter spacing?).

Yeah, I’m really trying to avoid buying an extra RD. I’ve got an extra eagle cassette, but those AXS RD’s are just stupid expensive (like $500 for the road version and $700 for the Eagle). If I can’'t just buy the eagle and run it with both road and MTB cassettes, I’ll buy the road version and just swap my Eagle AXS RD from my MTB when I want to run the 10-50 on gravel.

If anyone is interested, the following blog really gets into the nitty gritty of SRAM road vs. MTB compatibility along with some good 3rd party cassette alternatives. Basically, you can’t run the AXS Eagle RD with a SRAM AXS road cassette because the B adjustment can’t bring the RD in close enough because the biggest gear for AXS road only 33 teeth. There are several 12 speed cassette alternatives that provide tighter gear spacing (like an 11-42) compared to the Eagle 10-50 and can be run with the Axs Eagle RD. The article is a decent overview, but the comments section at the end is where they get into the details.