• 07-21-2019
    Fredrico
    Quote:

    Originally Posted by velodog View Post
    Originally there was one tire size that in combination with a 622 diameter rim made up a 700c wheel. That was then, now there are many different width tires that fit a 622 rim, from as small or smaller than 20mm on up thru 40mm or larger. The wheel has stayed the same since its inception, but the tire has changed, and the tires change is measured in mm's. It doesn't matter that the manufacturer calls the tire size 25c, they may not care or know the history and are just printing what they think is right or what they think that the market understands.

    Why would a nominal 28mm tire be called 28c? A mm is a known, whether they hit the mark, or miss, so why settle for a "c" that means nothing unless measured in conjunction with a 622 rim, and then is only, in reality, one tire size?

    Well shucks. A 622mm rim with a 78mm [about 3"] tire measures 700mm in circumference. So ok, if the original clinchers were that fat, one could note that as the original. So C does mean circumference. C makes more sense describing the roundness of the tire in area, width and height combined.

    I think whippersnappers hitting on us old timers saying the C word might be a cultural thing, along with Zwift, statistics and weekly opinion polls. As you say, precise millimeter measurements are more satisfying than references to circumference, even if they aren't any more accurate. Digital thinking likes quantifying with numbers. Letters are a throwback to the literary age. :D
  • 07-22-2019
    Lombard
    Quote:

    Originally Posted by Fredrico View Post
    Well shucks. A 622mm rim with a 78mm [about 3"] tire measures 700mm in circumference. So ok, if the original clinchers were that fat, one could note that as the original. So C does mean circumference. C makes more sense describing the roundness of the tire in area, width and height combined.

    Huh? I don't think the circumference of that tire is 700. :confused: And if c stands for circumference, what does b in 650b stand for? Sounds like you're making stuff up unless you're mixing up circumference with diameter.
  • 07-22-2019
    No Time Toulouse
    Quote:

    Originally Posted by Lombard View Post
    Huh? I don't think the circumference of that tire is 700. :confused: And if c stands for circumference, what does b in 650b stand for? Sounds like you're making stuff up unless you're mixing up circumference with diameter.

    As usual, Freddy is talking out of an alternative orifice. He gets confused, you know.

    First of all, remember your geometry: Circumference = 2*(pi)*r., and =2*r. With a diameter of 622mm, the r=311, so therefore the C of a 622D wheel without tires is 1,953mm. Obviously Frederico is completely ignorant in his post, or else he's getting confused in his old age. Now, let's "splain" what it really means:

    In the French/metric sizing system, there is 700A (642mm , obsolete), 700B (635mm , same as old British "28'" roadsters, rare today), 700C (622mm , common today), and 700D (583mm , odd, very close to 650B).
  • 07-22-2019
    den bakker
    cockpit
    gravel grinding.
  • 07-22-2019
    .je
    Any incremental change or substitution of one part for another is COMPLETELY DIFFERENT.

    This would be COMPLETELY DIFFERENT but is even it?

    https://www.youtube.com/watch?v=MFzDaBzBlL0
  • 07-22-2019
    Mapei
    Quote:

    Originally Posted by .je View Post
    Any incremental change or substitution of one part for another is COMPLETELY DIFFERENT.

    This would be COMPLETELY DIFFERENT but is even it?

    https://www.youtube.com/watch?v=MFzDaBzBlL0

    Great vid!