I got a crazy good deal on a 2018 Cannonade Synapse - So much so I didn't pay attention to it having huge wheels/tires (21c rims and 30mm tires) until I got home. So now I want to swap out the wheels so I can run smaller tires.

Iv'e never dealt with a thru axle before - What do I need to know when buying wheels?

The axle has a lot of numbers on it Rear: 17 L4 QR51X-12-160-P1.0-16.5 Front: 17 L1 RQ51M-12-125-p1.5-10

Other than knowing it is a 12mm axle, do I need to pay any attention to anything else? Didn't know if there was a width measurement or anything I needed to deal with.

Would I just use the axles that came on the bike with different wheels, or will I need to buy new axles?

  • 3
    Have you considered just replacing the tyres? You should be able to fit smaller ones on 21c rims.
    – KeithWM
    Commented Jun 19, 2018 at 7:23
  • 1
    Smaller tires might not even be faster unless you ride polished slabs of marble. My new wheels are 21c too and I plan to run 26mm tires (as measured), you don't need different rims for that. Commented Jun 19, 2018 at 9:47
  • 2
    If you have to buy new wheels it negates your 'crazy good deal'! 21mm rims are not huge, you can run 25mm tires no problem. Commented Jun 19, 2018 at 10:53
  • Interesting, the wheels say they recommend 35-62mm tires on them.
    – Adam Meyer
    Commented Jun 19, 2018 at 14:08
  • 1
    Yeah, I know it about the deal. The shop was closing, it was the last one, I was far from home, and it was in my favorite color 😂... Didn't look everything over by any means
    – Adam Meyer
    Commented Jun 19, 2018 at 14:08

1 Answer 1


When getting the same 142x12 and 100x12 standard wheels I advise to take note of the following:

  • If your frame requires special dishing or not. Synapse probably doesn't.
  • Outer rim width. With wider rims, the rim clearance might become an issue. Not your case, though.
  • Rotor fitting standard, 6 bolt or centerlock.
  • Freehub body, 10-speed or 11-speed HG, Campagnolo or whatever comes out next (SRAM XDR, Shimano Micro Spline).
  • Thanks! it was the 142x12 that that ended up being the answer.
    – Adam Meyer
    Commented Jun 19, 2018 at 14:10

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