SRAM AXS road hydro shifters and SRAM MTB disc calipers

[deluxerider]

Are SRAM AXS road hydro shifters and SRAM MTB disc calipers compatible? My CX frame has standard ISO disc mounts.

[hollowgram5]

Not sure about that, but you should be able to grab a set of eTap 11 era Post mount calipers and they'll work just fine. Or Hope RX4s.

[tepextate]

I’ve been looking into the same thing, but for Shimano instead. Hope RX4 are out since they can only do 180mm rotor up front. Here’s the response I got from them last week:

Our postmount RX4 *break caliper will only work with a 180mm rotor up front, on a 160mm rotor the caliper fowls the bottom on the mount. So you would need to purchase brake mount F HBMF (IS FRONT > postmount 180) and run a 180mm rotor if you wanted the RX4 barke to work.

[Kirk007]

Sram makes an axs post mount hrd - gotta pay for Red though....

[visusest]

Sram MTB calipers use 21mm pistons and road use 18mm so they are not interchangeable. Shimano uses the same piston diameter for MTB/road so those are interchangeable. Any Sram road (Apex/Rival/Force/Red) HRD caliper will work with the AXS levers. They are pricey as new service parts so used or take-offs will be significantly cheaper.

Edit: I didn’t realize AXS switched to 21mm piston calipers. Check the most recent Sram spare parts catalog to check which connecting bolts are used with AXS and MTB calipers to make sure they are compatible.

[hollowgram5]

Originally Posted by visusest

Sram MTB calipers use 21mm pistons and road use 18mm so they are not interchangeable. Shimano uses the same piston diameter for MTB/road so those are interchangeable. Any Sram road (Apex/Rival/Force/Red) HRD caliper will work with the AXS levers. They are pricey as new service parts so used or take-offs will be significantly cheaper.

That's not entirely accurate. The early stuff was that way, but looking at the AXS service doc it does say that the new monoblock calipers are 21mm pistons.

Link to PDF


Be mindful of what calipers are coming with the group you are purchasing. The etap 11 HRD calipers have a banjo bolt at the caliper, and use barb and Olive.


Mechanical shift stuff uses a barb and olive at the caliper with an "adapter."


Images stolen from current eBay listings because I can.

[Heisenberg]

for undisclosed reasons i have a few postmount Red AXS calipers kicking around if it worries you. i'll happily let a pair go for a song.

but yes, a standard single-piston SRAM mountain caliper should work a-ok with an AXS lever. see above re: 21/19mm pistons.

[visusest]

Originally Posted by hollowgram5

That's not entirely accurate. The early stuff was that way, but looking at the AXS service doc it does say that the new monoblock calipers are 21mm pistons.

Thanks - my bad. I haven’t dug into the AXS tech docs and I assumed they remained the same as the old HRD road stuff. I blame Sram’s new service site - you can’t look at the whole list docs and filter down to what you need which is what I’m used to doing.

[jwest]

Originally Posted by hollowgram5

That's not entirely accurate. The early stuff was that way, but looking at the AXS service doc it does say that the new monoblock calipers are 21mm pistons.

Link to PDF

Old but good thread. Are you still here? I'm setting up a hardtail mtb with drop bars using the latest sram red axs shifters and it sounds like the latest mtb level TLM calipers i have as extras would work if both are 21mm pistons?

[commonguy001]

Originally Posted by jwest

Old but good thread. Are you still here? I'm setting up a hardtail mtb with drop bars using the latest sram red axs shifters and it sounds like the latest mtb level TLM calipers i have as extras would work if both are 21mm pistons?

Not the same person but yes it works. I know a few who’ve done this and it works fine. Saying that I just put flat mount brakes on a IS frame and fork using A.S.Solutions IS to Flat adapters. Another option if you wanted to stick with your red calipers.

[sparky33]

See this SRAM compatibility chart

https://www.sram.com/globalassets/do...patibility.pdf

[EB]

Yeah, Level calipers are the way to go here.

[vertr]

What could happen if you use 19mm (Road HRD) calipers with current AXS levers? I have done this setup before discovering this chart and the brakes seem to work fine, but I'm wondering if I should stop riding that bike if there is some catastrophic danger I'm not aware of.

[sparky33]

Originally Posted by EB

Yeah, Level calipers are the way to go here.

fwiw I have a set of lightly used Level Ultimate TLM B1 levers&calipers for sale:
https://forums.thepaceline.net/showthread.php?t=301805

[ploop098]

Another good caliper option for you might be the Hope RX4+ brake calipers made for DOT fluid levers. They use a 4 piston design and are compatible with SRAM AXS road hydros. I know some people have mentioned that they have to run 180mm rotors with them, but I've found that using 180mm rotors isn't a bad thing, even if most forks have a max 160 rotor.