It's amazing how much of tire making remains a black art. The manufacturers really don't know exactly how wide the tire will be when it comes out of the mold. However, the size needs to be engraved in the mold before the first tire is made... So the Barlow Pass measures about 36-37 mm, depending on your rim width, after it has stretched some.
Since so many riders try to cram the largest tire possible into their frames, we also need to err on the side of caution when giving tire widths. If our 38 measured 39 mm, we'd get lots of returns: "Doesn't fit my bike." It also seems that everybody measures tire width differently. If you simply squeeze a caliper closed until you touch the tire sidewalls, you compress the tire. With supple sidewalls, you easily get a millimeters less than the actual width. The most accurate way to measure is by iteratively closing the calipers, 1 mm at a time. Start with 38 mm, see whether it rattles when you wiggle it. If it does, go to 37 mm, and so on. The last measurement where the caliper has some "play" is the tire width. If you compress the tire as you measure, you might find that a tire that should fit inside your frame does rub. (Ideally, you'll have so much clearance that two millimeters don't make a difference.) I no longer worry about a millimeter or two in width, but focus on the ride. I find that a great 30 mm tire rides so much more comfortably than a mediocre 35 mm tire. Width really matters only when comparing two otherwise identical tires. Jan Heine Compass Bicycles www.compasscycle.com Follow our blog at www.janheine.wordpress.com -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
