26 x 1 1/2…571 or 584

Submitted by FreeLander on Thu, 12/04/2025 - 20:34

I have a CCM bike tire that is 26 x 1 1/2. Sheldon Brown says its a ISO 584. Some posts on this site say 571. 
 

This is what is currently in the bike dor wheels:

Made In Canada
         142-1
      26 x 1 1/2
DUNLOP RANGER 
 
CHROME WHEEL
Engraved or stamped in 2 spots with 
F26 x 1 1/2 
 
CHROME HUB
       Falcon
Made in Canada

2 Comments

Submitted by T-Mar on Fri, 12/05/2025 - 10:03.

A 571 bead seat diameter was common on vintage Canadian bicycles, which is why you see it mentioned often on this site. Normally, I'd default to the rim marking, which would be F9 for 584 and F12 for 571.  In this case, the numeral(s) following the F seem to be missing.  If the rim is reasonably round, you could try measuring the diameter or rolling it out along a straight edge/line to determine the circumference. A 584 should be 599mm in diameter and 1835mm in circumference, while a 571 will be slightly smaller, at 585mm in diameter and 1794mm in circumference. 

Submitted by FreeLander on Fri, 12/05/2025 - 11:40.

Wonderful. Thanks for this T-Mar. Know the F9 and F12 relationshii to ETRTO measurement is really helpful to!