Bikes & Tech
Photo: Dan Cavallari | VeloNews.com

Technical FAQ: SRAM AXS Flattop chain compatibility

Is SRAM's new AXS flattop chain compatible with existing wide/narrow chainrings? Plus, more follow-up on a reader's question about shifting with limited hand strength

Have a question for Lennard? Please email us to be included in Technical FAQ.

Dear Lennard,
Have you checked if the new SRAM eTap AXS 12-speed flattop chain is compatible with existing wide/narrow chainrings, like from Praxis Works, Wolf Tooth etc.?
—Christian

Dear Christian,
It is not compatible with those chainrings. As I said two weeks ago, the 12-speed Eagle chain has standard-size rollers; the AXS chain does not. There are no chainrings that work with the AXS chain other than SRAM road AXS rings at this time. (You can use the Eagle chain with the Eagle cassette, and the rear derailleur with existing wide/narrow chainrings from Praxis Works, Wolf Tooth etc.)

Here is what Praxis Works has to say about it:
“Our current 1x Wave rings are not compatible with the new AXS (Flattop road) chain. Our 1x Wave rings are compatible with the Eagle 12-speed chain, though. You could run AXS as a 1x with our cranks and Wave chainring with an Eagle cassette and chain.

We recently acquired an AXS group and are currently testing all of our rings and cranks with it, so we’ll post more info on our website ASAP.
Ross McMahon
www.praxis-works.com”

And here is what Wolf Tooth says:
“All of our rings are Eagle compatible.

The new Flattop chain requires slightly narrower teeth, and we currently have those in an Easton direct mount round rings that we are launching soon.

Also, we will be cutting this tooth change into SRAM direct mount road/cx sizes, 110 BCD, and possibly 130 BCD over the coming months (probably 6-9 months to get all those converted over).
Brendan Moore
Wolf Tooth Components”
― Lennard

Dear Lennard,
Another question on running Force AXS with an Eagle AXS derailleur. I have an Open U.P. with Force 1×11 which I use for both road (11-32 cassette, 700x28mm tires) and gravel (10-42 cassette, 650Bx2.1 tires). My question is with Force 1 AXS. Which chain would I use with the 10-33 road cassette, the flat top road chain or the Eagle MTB chain?
— John

Dear John,
You would use the Red or Force 12-speed Flattop road chain with the SRAM 12-speed 10-33 road cassette (on an XDR freehub driver body). That’s because the tooth profiles on the SRAM 12-speed 10-33 (or 10-26 or 10-28) road cassette is cut to mate with the larger rollers and narrower inner width of the 12-speed Flattop road chain; an Eagle or aftermarket 12-speed chain would skip on that cassette.

You won’t be able to have your second set of wheels with a bigger cassette, however, unless you also switch the chain to the Eagle chain when you interchange the wheels and put a 10-50 Eagle cassette on that second wheelset. There is no cassette bigger than 10-33 that mates with the Flattop road chain. It you want that 650B wheelset to still have a larger cassette and don’t want to change the chain, your options are limited. If you were to instead do a mullet build with an Eagle or aftermarket 12-speed chain and an Eagle AXS rear derailleur, the only cassettes available to mate with that chain and derailleur are the various 10-50 or 11-50 SRAM Eagle cassettes, an 11-50 SunRace cassette, or a 9-46 or 9-50 eThirteen cassette. I suppose in theory you could have one wheelset with a 10-50 Eagle cassette (or a 9-46 eThirteen cassette) and another with a Campagnolo freehub and a Campagnolo 11-32 12-speed cassette, which I’m guessing would mate with the Eagle chain. But you’d lack the 10-tooth cog you really need with your 1X crank.
― Lennard

Dear Lennard,
What is the work around with 11-speed Di2 sprinter buttons that will work the new SRAM AXS group?

I’ve got the 12-speed group, but the SRAM blips are a POS on the handle bars as climbing buttons and totally worthless as a sprinter button placement.
— Len

Dear Len,
I have not done it. I imagine that you just splice them together, since both Blips and Sprinter shifters are just on/off switches.

If you look at this, you can get an idea of what to do with the Sprinter/Blip shifter hack.
As you can see, there are two wires inside, and there must be inside the Blip wires as well, since it has a two-conductor plug on the end. I think you would just splice the wires together like in this video.
― Lennard

Feedback on last week’s column:

Dear Lennard,
Shimano manufactures two 11-34T 11-speed cassettes (CS-HG800-11 or CS-HG700-11) which fit 10-speed Shimano/SRAM splined hubs. (Both also include the 1.85mm spacer required for use with 11-speed splined hubs.)

Shimano has also recently added direct support for these 11-34 cassettes to E-Tube, their Di2 configuration software for PCs or iOS/Android smartphones.

Best of luck to Frank getting back on his bike.
— John

Dear Lennard,
I suggest that Frank try a simple change to a 10-speed SRAM TT shifter. These shifters operate in a single plane that may be fine with the amount of hand strength he has and are much less expensive than a full conversion to 11-speed electronic shifting.
— Philip

Dear Lennard,
In today’s FAQ, your solution to Frank’s shifting difficulty seemed wonderful but very expensive. I think it may be worth mentioning bar end shifters. I believe either SRAM’s or Shimano’s 10-speed bar end shifters would work and retain index shifting at just a fraction of the cost and complexity of your proposal. Combined with Tektro/Cane Creek ergo brake levers, this might be an affordable and satisfactory solution.

I know bar end shifters don’t make sense for racing and the shifts required there, but I’ve found them wonderful for tens of thousands of miles of fast paced recreational riding.
— Zach

Dear Lennard,
For Frank:
I absolutely agree that electric shifting is the ultimate solution to this. But there may be a cheaper way: if he can find one, the throw on a 10-speed Red shifter is a lot smaller than the throw on 10-speed Force. From memory the first downshift on Red is at about half of the angle of the Force shifter.

For Glenn:
I also position my cleats as far back as they will go. I have to support my arches when wearing normal shoes, and I found that putting similar levels of arch support into my cycling shoes has alleviated a lot of the foot pain I previously experienced on longer rides.
— Phil
Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder and purveyor of non-custom bikes for big and tall riders. A former U.S. national team rider, co-author of The Haywire Heartand author of numerous cycling books including Zinn and the Art of Mountain Bike Maintenance available also on DVD as well as Zinn and the Art of Road Bike Maintenance, Zinn and the Art of Triathlon Bikes and Zinn’s Cycling Primer: Maintenance Tips and Skill Building for CyclistsZinn holds a bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to veloqna@comcast.net