eTap AXS Red Question

[Vamoots58]

Toying with trying eTap (coming from EPS) I believe I read somewhere that the FD will not accommodate a chainring larger than 50-tooth (i gather because of how tall a gear the 10-tooth rear cog affords). I am a Q-Ring guy, so my 50-tooth Q Ring has an oval profile that approximates a 52-tooth ring when in the 'larger' part of the oval. Does that mean I outta luck for AXS?? (I cannot accommodate the XD driver and AXS cassette on my Lightweights, according to Lightweight).

Thank you in advance for any thoughts!

[yinzerniner]

Toying with trying eTap (coming from EPS) I believe I read somewhere that the FD will not accommodate a chainring larger than 50-tooth (i gather because of how tall a gear the 10-tooth rear cog affords). I am a Q-Ring guy, so my 50-tooth Q Ring has an oval profile that approximates a 52-tooth ring when in the 'larger' part of the oval. Does that mean I outta luck for AXS?? (I cannot accommodate the XD driver and AXS cassette on my Lightweights, according to Lightweight).

Thank you in advance for any thoughts!

If you have to keep your Lightweights and Rotor chainring, yes you're out of luck.

While the official SRAM word is 50t max the FD might be able to work on larger rings depending on the mounting location and rings themselves, you need the AXS chainrings, Flat Top Chain and AXS cassette to work all together. Someone here (DAVE) has hacked together the Campy 12 speed chain and crankset with the AXS RD and Cassette, but the 12s Campy chain is a drastically different design than the Flat Top so time will tell if there's a shifting, wear or reliability penalty down the line.

Also you'd need the XD or XDR driver for a 12 speed cassette in back which the AXS derailleur can work with.

[Dave]

Anytime you mix different brands with new technology, you risk failure. If it doesn't work, you'll either have to change to all sram axs or sell the stuff at a loss. Of course the FD will need to be mounted 4mm higher.

As I posted recently, the axs chain is a #40 design, with slightly larger rollers, compared to a #41, like most other chains.

I've ridden my campy 12 bike with the axs chain quite a few times now, with no problems. The chain shifts perfectly and it's quieter than a Campy 12 chain. It's got the same 1/2 inch pitch, so there's no reason to think that chain life will be reduced.

[yinzerniner]

Anytime you mix different brands with new technology, you risk failure. If it doesn't work, you'll either have to change to all sram axs or sell the stuff at a loss. Of course the FD will need to be mounted 4mm higher.

As I posted recently, the axs chain is a #40 design, with slightly larger rollers, compared to a #41, like most other chains.

I've ridden my campy 12 bike with the axs chain quite a few times now, with no problems. The chain shifts perfectly and it's quieter than a Campy 12 chain. It's got the same 1/2 inch pitch, so there's no reason to think that chain life will be reduced.

The only problem with that thinking is that you're already working in a tolerance mismatch before riding a single mile. In an earlier post you mentioned the roller diameter difference of roughly 3%, which is similar to starting at 3% wear when most modern drivetrains recommend replacement of chains at 0.5% wear.

See this recent article in CT for more illumination:
https://cyclingtips.com/2019/08/bicycle-chain-wear-and-checking-for-it/

I know I'm simplifying it (ie getting the numbers completely wrong) but when the tolerances for the drivetrain are already so tight there doesn't seem to be much benefit to using a combination where contact and load points are so mismatched especially when it can drastically shorten the lifespan of very costly items (like Campy cassettes and rings).

[Dave]

Chain wear is measured by the increase in pitch. Both chains have the same pitch. The axs chain rollers have only a 2% larger radius. If you review the definition of the sprocket design, it's based on the roller radius.

The roller diameter is not part of the chain pitch measurement. Proper measurement of wear is taken between the pin centerlines.

When wipperman measures wear in their testing, it's done full length, between the holes in the inner plates at each end, after removing the quick link. .5% wear is a large increase in length of .270 inch on a 54 inch chain.

The only difference when using an axs chain with sprockets made for a #41 chain is a minute change in the contact point between roller and the sprocket. If their was a significant problem, it should show up immediately.

[bfd]

Toying with trying eTap (coming from EPS) I believe I read somewhere that the FD will not accommodate a chainring larger than 50-tooth (i gather because of how tall a gear the 10-tooth rear cog affords). I am a Q-Ring guy, so my 50-tooth Q Ring has an oval profile that approximates a 52-tooth ring when in the 'larger' part of the oval. Does that mean I outta luck for AXS?? (I cannot accommodate the XD driver and AXS cassette on my Lightweights, according to Lightweight).

Thank you in advance for any thoughts!

I guess the question to be asked is if you put a Campy 12 cassette on your lightweight wheels would it work with the Sram axs 12 drivetrain? I know 11 speed is compatible, but what about 12 speed?

Good Luck!

[Dave]

All you need to do to test the axs chain with the Q rings is buy a chain and try it. I put one on my 11 speed bike, very briefly, just as a test and it worked.

[Dave]

If you have to keep your Lightweights and Rotor chainring, yes you're out of luck.

While the official SRAM word is 50t max the FD might be able to work on larger rings depending on the mounting location and rings themselves, you need the AXS chainrings, Flat Top Chain and AXS cassette to work all together. Someone here (DAVE) has hacked together the Campy 12 speed chain and crankset with the AXS RD and Cassette, but the 12s Campy chain is a drastically different design than the Flat Top so time will tell if there's a shifting, wear or reliability penalty down the line.

Also you'd need the XD or XDR driver for a 12 speed cassette in back which the AXS derailleur can work with.

Your statement above is totally wrong. All I did was put an axs chain on my campy chorus 12 speed bike.

Also, in the case of the axs chain, the rollers have .003 inch more material on them, so the won't wear down to the size of a #41 chain roller until a lot of miles have been logged.

The chain designs are not drastically different. The only reason for the flat top is to increase the cross sectional area, to produce adequate strength with the exceptionally thin outer plates.

FWIW, the SRAM eagle chain is virtually identical in width to a Campy 12 chain and the axs is the narrowest chain on the market.

[John H.]

I have seen issues with front derailleur shifting using the native AXS chainrings- I would not want to add oval rings to the mix.

[yinzerniner]

Your statement above is totally wrong. All I did was put an axs chain on my campy chorus 12 speed bike.
Sorry, I got the setup completely reversed. My bad.

Also, in the case of the axs chain, the rollers have .003 inch more material on them, so the won't wear down to the size of a #41 chain roller until a lot of miles have been logged.
But in an earlier thread (https://forums.thepaceline.net/showpost.php?p=2585112&postcount=8)you stated:
The axs chain rollers are .311 inch in diameter, compared to .305 inch for other brands
That's .006" as opposed to .003", but still a 1% difference in chain roller width. I'm not sure if that 1% will really make a huge difference, but it's still a margin that is introduced willingly. And the "wear down" seems OK for the chain, but what if the larger roller diameter of the chain (which is only $35) leads to premature wear on the cassette ($120) and chainrings ($200). Doesn't seem like a good trade off for unknown performance.

The chain designs are not drastically different. The only reason for the flat top is to increase the cross sectional area, to produce adequate strength with the exceptionally thin outer plates.
Yeah this seems to be true, although it's also another way to make the chain narrower so it can work with the extra gear in back. Also it theoretically could make the drivetrain operate quieter since the slim profile means it has more elbow room.

FWIW, the SRAM eagle chain is virtually identical in width to a Campy 12 chain and the axs is the narrowest chain on the market.
Again this comes to perception. I measured the flat top chain at 4.95mm, and the Campy 12 speed chain is 5.15mm. Again a 1% difference, which might be trivial or might be important.

It just comes down to a simple question - is there any reason to run a flat top chain with a non-AXS groupset? Is it worth the possible lessened lifespan on a part that doesn't offer any real benefits over a matched part?

[Dave]

The .006 diameter difference is the same as .003 inch of extra material. The first is a diameter measurement and the second is a radius measurement. It will take quite awhile to wear down an axs roller to the same size as a new chain of any other type. KMC chains typically have smaller rollers when new, rather than a diameter of .305, like most #41 chains. No one seems to notice.

I just put an axs chain on my second bike with Campy 12, to give it a whirl. It will take a long time to determine how well the chain wears. Campy chains have always lasted longer for me than any other brand, but the quiet running of the axs has me intrigued.

I plan to occasionally swap back to a Campy chain, just to be sure that I get no chain skip.

What ends the life of most cassettes is a new chain that skips on the most worn sprocket. To avoid that problem, alternate the use of several chains, so you never put a new chain on a worn cassette. All of the chains can be used longer and new-chain skip will never occur.

Using the axs chain is highly unlikely to cause a chainring problem. Worn chainrings eventually suffer chain suck as the mode of failure. I've never worn out a chainring.