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Can I run my old SRAM cranks (53/39) along with new 12 speed Force axs 10/33 cassette or do I have to run new cranks too?

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    It would help if you specify exactly which cranks are in question and whether you're already locked in to your FD choice.
    – Nathan Knutson
    Commented Jan 2, 2023 at 4:22
  • What is your front and rear derailleur? Or the one you are planning to use? If you are planning on upgrading an older bike, check that your hub is compatible and count with the need of new shifters as well. If trying to put old cranks to a new bike, just get compatible ones.
    – Vladimir F Героям слава
    Commented Jan 2, 2023 at 10:08

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It’s not just that the 12s chain is narrower than your chainrings were designed for. The AXS chains (but not SRAM’s Eagle MTB chains) use a larger roller diameter as well. I’ve heard some people report cross compatibility, but the AXS chain’s rollers I’ll be very slightly too large for the valleys of the teeth. This might cause faster wear. I don’t know if it might be unsafe under very high load. I personally wouldn’t chance it.

Also, the AXS system was designed for relatively small chainrings. Most amateurs won’t ever need their 53/11. You will now have that and a 53/10 gear. Some men’s road pro teams asked SRAM to make 54/41 rings - but this was because of concerns over drivetrain efficiency, not because they actually need a 54/10. Remember that 54/10 is truly immense gearing, and you would be better off coasting down a descent steep enough where you could pedal that gear.

SRAM’s Rival AXS crankset is probably the cheapest current crankset with AXS-compatible chainrings. I believe that it only comes with a DUB (28.99mm) spindle, so you’d need a new bottom bracket. It’s possible that SRAM will release an even cheaper Apex AXS group around March, and I understand that they filed FCC patents for that group. (These are the rough equivalents of Shimano 105 and Tiagra, or Campagnolo Centaur and Veloce when the latter group existed.) That could be an even cheaper upgrade option if it is confirmed. Normally we don’t recommend products, but I don’t believe anyone makes AXS 2x chainrings for a 110mm 5 bolt BCD (assuming your crankset isn’t 130mm BCD). If you were going 1x, it’s probable that you could find a non-AXS 1x ring that could fit your crankset, but a road 1x group definitely isn’t for everyone.

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12 speed chain is too narrow for your cranks which i believe 10 or 9 speed. Even if the chain fits the chainring, you will have issues with chain dropping and sucking between chainrings.

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    The inner width is going to be 11/128" or 2.18 mm on all chains from 9 to 12 speeds. So if the roller size is the same, the chain will fit onto the chainrings just fine. It's the outer width that changes, which means narrower chains could very well get into places they shouldn't, like between the chainrings, or even between the crankarm and the outer chainring. Shifting could also be affected. 9 or 10 speed FDs could be too wide, and the chainring spacing between 9/10 speed cranksets could be different too (I don't know offhand if that does change).
    – Andrew Henle
    Commented Jan 2, 2023 at 13:36
  • Perfect observation, that's correct. Sorry I missed the inner width. And yes, front derailleur won't work right, and will either drop chain between chainrings or shift very hard, if it could
    – Barış Atasoy
    Commented Jan 2, 2023 at 15:17

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