Little thing about bicycle tire sizes
Not a major deal here, but when I'm reading tech bicycle email lists (such as these excellent ones) and Americans refer to tires using ISO rim sizes such as 559, 571 and 584, it makes me edgy. (Europeans and antipodians are excused at this point.)
Now, the systems for measuring bicycle tire sizes are a huge mess for a variety of historical reasons, as Sheldon Brown does a good job of explaining. But he neglects to mention something, and no one else ever seems to want to bring it up either. I keep wondering whether that's because it's so obvious, or because no one even realizes it.
I sure get the impression that most American bike riders don't know that a 559mm rim (standard mountain bike) is exactly 22" in diameter, a 571mm rim ("650c") is exactly 22.5", a 584mm rim ("650c") is exactly 23", and a 622mm rim ("700c") is exactly 24.5" in diameter.
Where did you think those funny metric numbers came from anyway?
Sure, it's important to know the metric dimension since that's how they're sold and what the rest of the world uses. But for us Imperial girls still living in an Imperial world, the size in inches tells us how big it really is, in an intuitively useful way.
Same deal with 35mm photo film, if you didn't know. Measure a piece some time. It isn't quite 35mm wide, but it's exactly 1 3/8" because Thomas Edison designed the film format (for motion pictures) and he never used metric units.
Should there be some kind of a clever name this kind of non-metric metrification?
Now, the systems for measuring bicycle tire sizes are a huge mess for a variety of historical reasons, as Sheldon Brown does a good job of explaining. But he neglects to mention something, and no one else ever seems to want to bring it up either. I keep wondering whether that's because it's so obvious, or because no one even realizes it.
I sure get the impression that most American bike riders don't know that a 559mm rim (standard mountain bike) is exactly 22" in diameter, a 571mm rim ("650c") is exactly 22.5", a 584mm rim ("650c") is exactly 23", and a 622mm rim ("700c") is exactly 24.5" in diameter.
Where did you think those funny metric numbers came from anyway?
Sure, it's important to know the metric dimension since that's how they're sold and what the rest of the world uses. But for us Imperial girls still living in an Imperial world, the size in inches tells us how big it really is, in an intuitively useful way.
Same deal with 35mm photo film, if you didn't know. Measure a piece some time. It isn't quite 35mm wide, but it's exactly 1 3/8" because Thomas Edison designed the film format (for motion pictures) and he never used metric units.
Should there be some kind of a clever name this kind of non-metric metrification?