Originally Posted by
cyccommute
There's a whole other world of 26" tires you haven't taken into account as well. I won't go into it other than to say that 26" fractional (26x 1 1/2") and 26" decimal (26x 1.50") are two different sized tires.
Not always. Continental has the Gatorskin advertised as 26 1-1/8. It's a 559 mm tire which one would expect to be 26 X 1.125 (or 1.13, for pedants).
See here. This tire was discussed here not too long ago and I was unsure of what it was -- I suspected 650c. But, people who actually own these tires find them to work on 559 mm rims. Some ads make clear that although it appears to be "fractional" rather then decimal, it's a 559 mm tire. Probably should be referred to as 559 X 28, or maybe 29.
As for using bsd rather than marketing labels or labels like 26", 27" 28" 29", you're right.