26 Inch Wheels: Have They Changed Since 1933?
Found this on Sheldon Brown's website:
"Let's start with the 26 x 2.125 size that became popular on heavyweight "balloon tire" bikes in the late '30's and still remains common on "beach cruiser" bikes. This size tire is very close to 26 inches in actual diameter. Some riders, however were dissatisfied with these tires, and wanted something a bit lighter and faster. The industry responded by making "middleweight" tires, marked 26 x 1.75 to fit the same rims. Although they are still called "26 inch", these tires are actually 25 5/8", not 26". This same rim size was adopted by the early pioneers of west-coast "klunkers", and became the standard for mountain bikes. Due to the appetite of the market, you can get tires as narrow as 25mm to fit these rims, so you wind up with a "26 inch" tire that is more like 24 7/8" in actual diameter!"
He first says that new "middleweight" tires were produced to "fit the same rims." Then he says "this same rim size was adopted...." implying that these "middleweight" tires are made for a different size rim. Which is it? Did the rim size change? Or is it a typo and he meant to say "this same tire size was adopted..."
If that's the case, then it seems like he's also saying that for a given rim size, the tire diameter will change with the tire's width. It goes from (26 x 2.125) to (25 5/8 x 1.75) to (24 7/8" x 25mm), all on the same rim. How is it that a 24 7/8" diameter tire will fit on a nominally 26" rim? Sorry, I'm having a hard time getting my brain around this too.
Originally Posted by climbinrocks