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  #1  
Old 12-06-2020, 10:35 PM
deluxerider deluxerider is offline
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SRAM AXS road hydro shifters and SRAM MTB disc calipers

Are SRAM AXS road hydro shifters and SRAM MTB disc calipers compatible? My CX frame has standard ISO disc mounts.
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  #2  
Old 12-07-2020, 08:46 AM
hollowgram5 hollowgram5 is offline
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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.
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  #3  
Old 12-07-2020, 08:52 AM
tepextate tepextate is offline
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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.
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  #4  
Old 12-07-2020, 10:28 AM
Kirk007 Kirk007 is offline
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Sram makes an axs post mount hrd - gotta pay for Red though....
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  #5  
Old 12-07-2020, 03:19 PM
visusest visusest is offline
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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.

Last edited by visusest; 12-07-2020 at 08:55 PM. Reason: Wrong info
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  #6  
Old 12-07-2020, 06:30 PM
hollowgram5 hollowgram5 is offline
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Quote:
Originally Posted by visusest View Post
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.

Last edited by hollowgram5; 12-07-2020 at 06:37 PM.
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  #7  
Old 12-07-2020, 06:55 PM
Heisenberg Heisenberg is offline
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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.
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  #8  
Old 12-07-2020, 08:49 PM
visusest visusest is offline
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Quote:
Originally Posted by hollowgram5 View Post
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.
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  #9  
Old 12-09-2023, 05:50 AM
jwest jwest is offline
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Quote:
Originally Posted by hollowgram5 View Post
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?
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  #10  
Old 12-09-2023, 09:13 AM
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commonguy001 commonguy001 is offline
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Quote:
Originally Posted by jwest View Post
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.
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  #11  
Old 12-09-2023, 11:44 AM
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sparky33 sparky33 is offline
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See this SRAM compatibility chart

https://www.sram.com/globalassets/do...patibility.pdf
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  #12  
Old 12-09-2023, 12:38 PM
EB EB is offline
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Yeah, Level calipers are the way to go here.
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  #13  
Old 12-09-2023, 03:26 PM
vertr vertr is online now
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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.
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  #14  
Old 12-09-2023, 04:20 PM
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sparky33 sparky33 is offline
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Quote:
Originally Posted by EB View Post
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
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  #15  
Old 12-10-2023, 12:44 PM
ploop098 ploop098 is offline
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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.
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