KMC X12 Chain

Is anyone using a KMC X12 chain on any of SRAM’s AXS road groupsets?

I’m looking for an alternative to the SRAM flattop chains on an upcoming Red AXS build and have had great performance from KMC chains on other gorupsets 11 speed and below. The KMC chain is not of the flat top design.

I believe KMC advertise it as being compatible, but I have no personal experience.

In theory, any chain with small enough diameter rollers will work at least reasonably well because the pitch is the same.

However, there may be a slight mismatch in contact points because (iirc) the rollers aren’t exactly the same size. That could lead to accelerated wear and shifting that possibly deteriorates over time. It’s all maybes, though.

But given how long AXS chains last, and that Force chains offer most of the performance of Red at a substantially reduced cost, I personally wouldn’t be going away from that chain on an AXS build.

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KMC do advertise it as being compatible with SRAM 12 speed road groups.

I would anticipate the roller diameter to be the same since the chain is listed as compatible but I haven’t had my hands on the KMC version yet to compare measurements.

My reasoning behind installing a KMC chain over the SRAM is twofold. One - the CyclingTips article “Finding the Best Bike Chain” with data from Zero Friction showing KMC chains in general to be more efficient than SRAM AXS and two - past personal experience with solid reliability, performance, and ease of submersive wax treatment.

Someone will probably comment that if I want efficiency go with the larger chainrings and cog of Shimano. But, all that aside, I am curious about the shifting performance of the KMC 12 speed chain on an AXS groupset and more importantly the strength of the chain. The KMC does not have the “flat top” feature that SRAM tout as necessary for strength due to the thinner outer plates.

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The note from the ZFC website mentions that the SRAM Road Set has smaller rollers than other chains leading to incompatibilities with other brands, though reference
to KMC is missing.

It’s a proprietary issue: one of SRAM trying to lock consumers into their consumables.

https://zerofrictioncycling.com.au/product/12-speed-chain/

KMC may be able to shed some light on the roller size issue.

I can’t find where KMC says that this is compatible with road AXS groups. The Flat Top chain is different enough (larger rollers, taller profile, etc.) that I can’t imagine how an Eagle compatible chain could run well on an AXS road cassette.

Do you have a link to this compatibility breakdown?

Perhaps I am inferring road AXS compatability from the following specs from KMC’s website:

Compatability: Shimano, SRAM and all other 12 speed drivetrains
Suitable for: Road Bike, etc.
One chain for all, 100% compatability on all leading derailleur systems

This is from the following link as also found in the original post:

The chain I am referring to has a 12 on the side of the outer plates. There is another version of 12 speed chain that instead has an X in this position and is listed by KMC as compatible with SRAM Eagle.

I don’t disagree that the likelihood of a chain that is compatible with other systems also being compatible with SRAM road AXS is slim, especially due to the larger roller size as you mention and correspondingly sized “valleys” of the cassette and chainrings

Along this line, I question the validity of the efficiency results from Zero Friction as they pertain specifically to SRAM AXS chains. If I recall correctly these chains were tested on a non AXS drivetrain. To be fair, I believe they did clearly state this shortcoming of the test due to availabilty of AXS drivetrains at the time. Perhaps a follow up has been done testing the efficiency of the system as a whole?

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Something that may or may not help you deciding: I found the KMC 12-speed chain not so universally great. But then again, I have a specific setup with an Ingrid cassette. (12-speed, classical cog spacing and for classical chain rollers) And on my system, classical SRAM 12-speed chains are the most stable, over Shimano and KMC. Where the KMC chain is the most “nervous” (the most responsive to derailleur position) and makes the most noise.

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Well I guess let us know how it works if you try it! I hate the AXS chains since they don’t have reusable quick links and they make lots of noise…. And they’re proprietary and too expensive. Other than that they’re great!

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I think the Force chains are very similar to Ultegra chains in price (in fact, in the UK the Ultegra 12sp are marginally more expensive). Officially you can’t reuse the power links, but I routinely used them twice without problems. And again, the situation isn’t any different with the Shimano 12sp chains AFAIK.

There are things about AXS I don’t love, but the chain isn’t one of them.

Hi, this document link from ZFC may be useful. It’s helpful info about chain master links however scroll down to the last 2 pages in the 12sp chain section….

This is great, and lines up with my experience that YBN chains are fantastic (and you can reuse the quick links 5 times).

I’ve tried reusing the SRAM links but I’ve had them pop off. So no thanks.

I am running a KMC chain 12 speed ultegra cassette and a rival AXS crank set. It shifts perfectly, a little noisy, and seems like it fits better with the teeth on the cassette and the teeth on the chainrings. But overall, gets the job done.

I added a X12 DLC to rotate with a Red AXS flattop. Running full Red AXS (46/33 - 11/33) on a V3RS. I’ve done one ride so far; it is louder and seems a bit off at certain cogs with a hint of the “skipping sound” while climbing. Tried trimming the rear but didn’t seem to help. Seems to shift quite well on the stand so perhaps only have some issues under load. Haven’t had a chance to investigate further unfortunately. If you do try would be interested to see your results.

Thank you @mattbrown399 for the link to the ZFC document. That pretty well seals the deal for me to stick with SRAM Red and Force AXS chains on this drivetrain. That along with the ride experiences of @Dan_Mahoney and @Chuckmeister (thanks to both of you as well) seem to indicate a smaller roller diameter on the KMC chain. This to me would be like installing a badly worn chain on a brand new (expensive) drivetrain. I still would be curious, however, to see what the measurable difference is in roller size between the KMC and SRAM AXS chains if anyone is inclined to get their vernier calipers out.

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I use all three of YBN gold (the to-nitride one), KMC X12 and SRAM flattop. All work fine. YBNnis my race chain, flattop for training as the zero friction review shows it is less efficient but very hard wearing. Have KMC on my gravel bike (with AXS force wide) and that is also great. No problems with any of them.
Top tip - KMC and YBN chains are much cheaper from somewhere like AliExpress, at least to the U.K. but you have to be willing to wait a month for them to arrive to realise this saving!