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Huh. I thought the C in 700C indicated that the tire was a clincher as opposed to tubular but that seems to be wrong. You tool says: > Reifenhöhe C: ca. 39 mm

Huh. I thought the C in 700C indicated that the tire was a clincher as opposed to tubular but that seems to be wrong. You tool says: > Reifenhöhe C: ca. 39 mm (French designation) but it says that for 700x19C as well as for 700x40C which seems odd? The wikipedia page for Bicycle wheel [1] says: > The ISO 5775-2 standard defines designations for bicycle rims. It distinguishes between 1. Straight-side (SS) rims 2. Crochet-type (C) rims (...) and also > Road wheels may be designed for tubular or clincher tires, commonly referred to as "700C" tires. but it doesn't explain the B in 650B. Sheldon Brown [2] says (emphasis added) > A second number or letter code would indicate the *width* of the tire. (26 x 1.75, 27 x 1 1/4...650B, 700C...) The wikipedia page does mention both 650B and 650C and that the ISO diameter differs by a few mm. So if I understand right, these codes (650B and 700C) specify the full-wheel diameter (650/700) and the letter indicates how much of that diameter the tire needs to make up, i.e. a 650B rim is slightly smaller (571mm) than a 650C (584mm) and the tire needs to make up that differencxe to get to 650? [EDITED] 700C rims are ISO diameter 622mm, which matches with 2x 39mm tire width: 622 + 78 = 700mm. So I guess the intended tire height at time of standard-invention was 39mm? But in practice a 700x19C rim-tire combo will be smaller in diameter than a 700x40C so I guess they're not fully "700C" standard compliant? [1] https://en.wikipedia.org/wiki/Bicycle_wheel#650B_gravel_bicycle_wheels_/_ISO_584_mm https://en.wikipedia.org/wiki/Bicycle_wheel#650B_gravel_bicy... [2] https://www.sheldonbrown.com/tire-sizing.html https://www.sheldonbrown.com/tire-sizing.html

moasda 5y ago
Wow, thank you very much for the valuable information. I will check how to improve the page accordingly.
sasawpg 5y ago
Pasted description below from Sheldon's page. The A/B/C designation is even more confusing when you consider 700C wheels/tires which these days range from the uncommon 19mm to well over 40mm. In the French sizing system, tires are designated by a three-digit number, which may be followed by a letter. The number is the nominal outside diameter of the tire the rim was originally designed for. The absence of a letter indicated a narrow tire; "A", "B" and "C" indicated increasingly wider tires."A" was originally a tire about 30 mm wide, so the 650A rim is pretty large, 590 mm. If you add the top and bottom 30 mm tire thickness to 590, you wind up with the 650 mm tire diameter. The 650C size was originally intended for a quite wide tire, about 40 mm wide. Top and bottom 40 mm tire plus the 571 mm rim size again bring you to a 650 mm outside diameter, even though the rim was smaller.
Matthias247 5y ago
Interesting historic context! My understanding is that in the current world the suffix doesn't really matter, since all 28" rims and tires are marketed seem to be marketed as 700c, and all 27.5" ones as 650b. The height of the tire pretty much correlates with the tire width, so one would rather look at the tire and rim width to determine whether they are compatible (wider rims should be used for wider tires). And it's actually fun that 700c bikes are usally ridden with narrower and lower tires than 650b bikes (which was in the recent years mostly used for mountain bikes and tire width of >= 2.3"), despite this designation claiming the opposite.
- comprev 5y ago
  Pinkbike has a good article on rim width [1] [1] https://www.pinkbike.com/news/rim-widths-comparison-test-mountain-bike.html https://www.pinkbike.com/news/rim-widths-comparison-test-mou...
- petre 5y ago
  Actually 650b is used when the tire width is less than 50 mm (randonneur and gravel bikes) and 27.5" when the width is over 50 mm (mountain bikes). Jan Heine and Kirk Pacenti reintroduced this size.
- switchbak 5y ago
  In the mountain bike world, there's really only two modern standards - 650b (also called 27.5in) and 29er's. 26er's were a thing for the longest time, but really no one makes new bikes in that size anymore. We're mostly riding on wider tires, 2.3 seems to be a rational minimum for real trail riding, and you'll often see widths of 2.6 and beyond (and fat bikes of course go way wider) on both 27.5 and 29in bikes.

moasda 5y ago

Wow, thank you very much for the valuable information. I will check how to improve the page accordingly.

sasawpg 5y ago

Pasted description below from Sheldon's page. The A/B/C designation is even more confusing when you consider 700C wheels/tires which these days range from the uncommon 19mm to well over 40mm. In the French sizing system, tires are designated by a three-digit number, which may be followed by a letter. The number is the nominal outside diameter of the tire the rim was originally designed for. The absence of a letter indicated a narrow tire; "A", "B" and "C" indicated increasingly wider tires."A" was originally a tire about 30 mm wide, so the 650A rim is pretty large, 590 mm. If you add the top and bottom 30 mm tire thickness to 590, you wind up with the 650 mm tire diameter. The 650C size was originally intended for a quite wide tire, about 40 mm wide. Top and bottom 40 mm tire plus the 571 mm rim size again bring you to a 650 mm outside diameter, even though the rim was smaller.

Matthias247 5y ago

Interesting historic context! My understanding is that in the current world the suffix doesn't really matter, since all 28" rims and tires are marketed seem to be marketed as 700c, and all 27.5" ones as 650b. The height of the tire pretty much correlates with the tire width, so one would rather look at the tire and rim width to determine whether they are compatible (wider rims should be used for wider tires). And it's actually fun that 700c bikes are usally ridden with narrower and lower tires than 650b bikes (which was in the recent years mostly used for mountain bikes and tire width of >= 2.3"), despite this designation claiming the opposite.

comprev 5y ago
Pinkbike has a good article on rim width [1] [1] https://www.pinkbike.com/news/rim-widths-comparison-test-mountain-bike.html https://www.pinkbike.com/news/rim-widths-comparison-test-mou...
petre 5y ago
Actually 650b is used when the tire width is less than 50 mm (randonneur and gravel bikes) and 27.5" when the width is over 50 mm (mountain bikes). Jan Heine and Kirk Pacenti reintroduced this size.
switchbak 5y ago
In the mountain bike world, there's really only two modern standards - 650b (also called 27.5in) and 29er's. 26er's were a thing for the longest time, but really no one makes new bikes in that size anymore. We're mostly riding on wider tires, 2.3 seems to be a rational minimum for real trail riding, and you'll often see widths of 2.6 and beyond (and fat bikes of course go way wider) on both 27.5 and 29in bikes.