"New Generation" KMC 12 Speed Chains -- Updated 12 Speed Chainrings -- AXS Road Compatibility & Mix/Matching?

Ok, let me start by saying I know there is a lot of discussion out there on these topics, but please humor me on this one a bit. I more or less understand the following about AXS road, and what SRAM will tell you regarding the system as the “party line”:

  1. Only SRAM’s Flat Top Chain is compatible with AXS Road components;
  2. The Flat Top Chain has larger-than-standard rollers, and therefore requires different chainring/cassette tooth profiles or valleys;
  3. SRAM AXS Road rear derailleurs have special jockey wheels to mesh with the Flat Top Chain;
  4. The chain spacing and cassette spacing is different than with other manufacturers’ 12 speed components.

Having said all of this, other manufacturers are beginning to advertise their components as more or less “universally” 12 speed compatible in one way or another. Just a few examples:

  1. Praxis now states that certain rings are 12-speed compatible, including SRAM Flat Top/AXS – Praxis Site LINK;
  2. KMC’s newest generation 12-speed chain now states it is compatible with “Mountain bike and ROAD systems from SRAM, Shimano, Campagnolo, and other manufacturers” – KMC’s Site LINK

So, assuming an AXS Road user wanted to start mixing/matching components from the various groupsets to move away from SRAM’s X-Range gearing into a more “conventional” setup like a 52/36 up front, and a 11-32 or 11-34 in the rear, is there really anything stopping someone from cobbling something like that at this juncture?? Another option could be to simply change up front to get even more range – 50/34 up front, and 10/33 out back, for climbing. To me, the biggest issues would seem to be the following:

  1. SRAM states AXS rear derailleur jockey wheels are specifically designed to work with the Flat Top chain; and
  2. Front shifting on the AXS Road setup may be somewhat iffy with a 16 tooth jump

However, I’ve always been a bit unclear on whether the problem with AXS jockey wheels is 1) the AXS Road rear jockey wheels won’t mesh with other chains; or 2) other jockey wheels won’t mesh with the Flat Top chain (due to its width). Also, with regard to front shifting, I’ve heard that others have gotten 16-tooth gaps working on the SRAM AXS front derailleurs.

Now that I’ve rambled on for a while, has anyone here tried any sort of AXS mix/match combos, whether chains, chain rings, third-party cassettes, or any combo of the foregoing? If so, what has your experience been? Myself, I’ve had good luck with aftermarket Carbon-Ti chainrings so that I can use my existing Quarq power meter with AXS. However, these follow SRAM’s X-Range gearing ratios (48/35, 46/33, etc.). I’m curious as to the other options as more 12 speed components become available.

Thanks!!

I have been using Kogel jockey wheels with my Force AXS and have not noticed any degradation in any way.

I use 11-speed Red 50/34 chainrings with AXS flat top chain and a Red AXS 10-28 cassette. It works perfectly well.

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Did you use the AXS FD alignment tool to install with the 11-speed rings, or did you install the FD without the aid of this tool?

I briefly experimented with some 11-speed rings prior to purchasing the much more expensive Carbon-Ti X-Range rings, just to see if I could get decent shifting. I had mixed success, even using the FD alignment tool. I assumed this was due to the larger 16-tooth between front chanrings, but maybe I just didn’t nail the setup. I’ve had great shifting with the Carbon-Ti, though. So, who knows.

I didn’t use the alignment tool. I just rotated the crank very slowly while making the front shift to understand exactly what it is was trying to do. When the chain gets lifted, the FD cage needs to be at the right angle before it hits the “bump” on the inner cage of the FD to make the jump.
Haven’t had a single dropped chain.

I also used for some time a 50/34 Dura -Ace 9100 crankset and that one was even easier to set up and worked perfectly as well.

What’s the point of 12sp in the rear if you’re 2x in the front? 1x with a big cassette is better than 2x small cassette (one less thing that needs adjusting too), especially for bumpy road/offroad. I wouldn’t fret the 1x chainring - this is helpful if you’ve got a huge cassette and rear suspension, but not really important for road/gravel duty (when was last time you dropped a chain while in gear on 2x??).

Yes… the CHAIN has bigger round bits.
The CHAIN only works with AXS stuff. BUT the rings and cassette work with the Eagle chain (normal, but 12sp narrow). The SRAM Eagle X01 and XX1 chains last for foreverever, the same price as the KMC, and come in color colors.

The jockey wheels are $30 expense and 10min job to swap out on the RD.

Just about everyone makes 12sp chainrings. If you’re going gravel, use the Eagle chain or Shimano’s HG+ Chain and cassettes.
https://blog.3t.bike/2019/09/12028/gravel-tech-hacking-sram-axs-drivetrains/

On a road bike 1X isn’t great drive train loss is extensive the smaller you go on the rear cassette

It’s not 1x that’s the cause, it’s the smaller cog and NW ring. You can do without the NW ring. If you run the same size ring as your big ring, you won’t have any loss.

Plenty of TT and Ironman riders on 1x, as you realize about 1-4w aero savings even with the bigger cassette (or 15 if you look at the one with a riderless bike at 30mph LOL)

It’s not extensive, it is fine. Increasing cog size at the same ratios will give you a marginal gain, which is probably not relevant for most riders. Being able to hold a more aero position, for example, will have much larger impact than what you do with the drive train.

@finncox23
I’m a little bit confused because I don’t understand the purpose: typically, you’d want to mix-and-match for one of three reasons:

  1. You want to re-use old gear, e. g. an 11-speed Red crank you have laying around.
  2. You want to go beyond officially supported gearing ranges and ratios.
  3. You want to save money.

After reading your post, I don’t understand your motivation at all. Why do you want to do this?

The problem as I see it is that perhaps your drive train can handle one component that is out of spec or two. But once 3 or 4 are out of spec, I think the probability that your drive train just won’t work well will increase significantly. E. g. if you use traditional 11-speed chain rings with a 11-32 cassette, 50/34 chain rings and a non-SRAM chain, I think you might easily run into issues.

So yes, you might cobble something together, but you’d be outside of spec on multiple counts. For example, there is a 50/37 chain ring option, and using a 50/34 combo means you would be out of spec with the front derailleur.

This is a fair point given what I’ve written, so perhaps I should clarify a little. My initial motivation:

  1. Find cheaper 110x5 BCD chainrings to replace my Carbon-Ti when they wear out.

When I bought my AXS system, I had a relatively new, 110x5 BCD Quarq DUB DZero power meter than I wanted to continue using. At the time, the only real truly (or purportedly) compatible chainrings were Carbon-Ti, which are nice, but super expensive. When these wear out, my main motivation is to spend less than $400 on replacement chainrings, or buying another AXS-specific power meter. Also, to your point on range, swapping out the SRAM “X-Range” front rings with more traditional 50/34 would actually give more range if you keep a SRAM cassette in the mix, as compared to my current 48/35 setup.

As far as the rest of my questions… As I thought about it some more, I am a little annoyed with some of the decisions that SRAM has made when it comes to the AXS system. Yes, their gearing technically increases range. Yes, they have “more 1-tooth” jumps in a lot of their cassette progression. However, couldn’t they have just gone with more standard options to increase range, like adding a 48/32 chainset to the bottom end? Also, for all of their ranting about “1-tooth jumps” on a lot of their cassettes, the jump from the 10-tooth cog to the 11-tooth is a bigger percentage jump than 11 to 12, regardless of the tooth count. Also, they could make a 12-speed chain that works with Eagle AXS with more standard rollers/sizing, but they have to change the chain for the same system on road AXS setups? I’m just curious about the functionality of other options that accomplish basically the same ends without going completely proprietary.

I see the utility of the 10-tooth cog when it comes to 1x groupsets (and have one myself), but I’m a tinkerer, so my interest is piqued, that’s all.

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What crank do you have now?
I think quite a few companies make 12-speed-compatible chain rings. Rotor comes to mind, but I am sure there are others.

Yes, but do you know whether you will still have reliable shifting? I don’t. (I run my Force eTap AXS 1x, so I don’t know.)

Yes, but is it a meaningful difference? In my experience no, shifting into my 10-tooth cog now doesn’t feel any different than going from my 12- to my 11-tooth cog. To be honest, I don’t spend that much time in my 11-tooth cog, SRAM tells me that I spend much more time in the 12-, 13- and the 10-tooth cogs (the 12- and 13-tooth cogs are for fast cruise, the 10-tooth cog is my overdrive gear).

I guess. I don’t know why SRAM went with a flattop chain, and simply using the same chain as their mountain bike group sets would be nice. But honestly, it is fine.

(My mountain bike has an 11-speed XTR drive train anyway. But it’d be nice to simply be able to simply have to stock one type of chain for all your bikes.)

The 10-tooth cog significantly increases range, and that’s useful for 2x as well.

Quarq DUB DZero 5x110 BCD Crank/Power Meter. Great power meter, and I wanted to avoid buying an entirely new Quarq, AXS-specific setup for essentially the same power meter internals.

I agree with you, but to your point about spending more time in the 12 & 13 tooth cogs, how often is the extended top end range really needed? Functionally, they could have accomplished the same goal of adding more range on the bottom end by way of a more “conventional” 52/36, 11-34 setup, and then having alternates for 50/34 and 48/32 for even more low-end range. Functionally, 52/36, 11-34 is about the same as their current 48/35, 10-33 setup, but would have avoided the need change literally everything else about the groupset that can sometimes prove annoying.

Maybe at the end of the day I’m just looking for an excuse to tinker, as I get bored sometimes and like to mess with my bikes… :roll_eyes: …much to my spouse’s chagrin.

I think you have wrong idea about my gearing: I did not extend the top end at all. I have a 42-tooth chain ring and a 10-36 cassette. My top gear is equivalent to 50:12 or 46:11, and my easiest gear has a slightly lower ratio than 34:28. When I go fast on (false) flats at about 50 km/h, I am typically in 50:13 or 42:12. I prefer a faster cadence at those speeds. I typically only use my top gears when going downhill. That leaves the 42:11 and 50:12 as the odd gears out.

I obsessed a lot about gear ratios when I went 1x.

No, there are differences, have a look. One essential difference is that Shimano’s equivalent gearing combo has one less cog at the top end which is 1 tooth apart from its neighbors as well as a larger overlap between the usable gears in big and small chain ring (since big and small ring on SRAM’s 12-speed groupsets only are 13 teeth apart rather than 16 on Shimano).

I think gearing is where SRAM has Shimano absolutely beat, it’s not even close: you have a lot more options. You can go 1x or 2x, both are fully supported on drop bar bikes. I like that SRAM lets riders choose rather than force that decision upon them like Shimano does. And then there is a whole host of cassettes, starting from 10-26 (which is probably super niche), 10-28, 10-30, 10-33 and 10-36. All of these cassettes are supported on 1x and 2x. A 2x setup with 10-36 gives you almost 500 % range, way, way bigger than anything Shimano can (even with a mullet setup since their Di2 mountain bike groupsets are still all 11-speed). On 1x, you can use all the aforementioned cassettes in addition to a 10-44 with a road-style RD or 10-50 or 10-52 with a mountain bike rear derailleur.

The 10-tooth cog is essential for keeping the size of the cassette down. For example, you’d need a 11-48 cassette to mimic a 10-44 cassette. Or an 11-40 cassette instead of a 10-36.

I think Shimano’s direction with gearing, which is closely tied to the pro peloton, is really making their products less good for non-professional riders, i. e. pretty much all of their customers.

2X12 makes sense for heavier road cyclists who need more range but don’t want big jumps between cogs.
It makes zero sense for me to anyone to bother with 12 speed if they’re using an 11-30, though.

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The 12-speed 11-30 cassette (I assume you are referring to Shimano’s 11-30 cassette) indeed does not make much sense to me either. Even when I was on 11 speeds, I put a SRAM cassette on my road bike, because I preferred their gearing choices, Shimano’s tendency to have small jumps at the easy end of the cassette makes no sense to me.

Anyone on here tried the latest KMC 12 speed chain with Road AXS? General consensus is that all the SRAM 12 speed chains are really slow, so keen to get something that’s a bit quicker