Carl Spackler wrote:
Factor did a lot of cool things with that frame but designing a "pure gravel bike" with only 35mm (stated) tire clearance is a head scratcher.It fits a true 40. The Gravel King 38 measures 40mm, and it fits.
I think companies would rather be on the safe side when recommending tire size because the actual size varies so much on different rims. Some 40s measure 44mm, so a frame company won't want to say "we fit 40c tires" because it would lead to disappointment when somebody tries to squeeze their 44mm tire that says "40" into a frame that can only fit a true 40.
In at least 75% of the races i did last year, i used 35s (which measure 38). In a couple races I used 32s. There was only one race that I used something bigger than a true 40. I raced in Colorado, Kansas, Oklahoma, Texas, Arkansas, Nebraska, Michigan, and I guess technically part of MO.