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  1. #1
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    CO2 Yield Question

    A 16g CO2 cartridge will file a 700x23 tire to 130 P.S.I. (that is most certainly under ideal conditions with absolutely no leakage, I doubt you can actually get that yield on the road).

    If that is the yield for a 700x23 tire, what do you think that yield would be on a 700x28 tire? Getting a commuter and would prefer to just slip a cartridge and tiny valve in a gadget bag that carrying a pump.

  2. #2
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    106.8 psi

  3. #3
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    A different number

    Quote Originally Posted by litespeedf1
    106.8 psi
    Comparing the cross section of the tires: 130 x 23^2/28^2 I get 87.7 psi

  4. #4
    Steaming piles of opinion
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    Quote Originally Posted by Kerry Irons
    Comparing the cross section of the tires: 130 x 23^2/28^2 I get 87.7 psi
    Square tires? Might as well use a random number generator.

    It should be the volume of the two toroids that we're comparing.

    The volume of a torus is defined as 2pi^2Rr^2. If we use the 622bsd + r (11.5 or 14, respectively) as R, we get 87.37 psi.

    I bet he's using clinchers. Tosses that right out. Sigh.

    Get a pump. Lighter, more reliable, and not meaningfully slower.
    A good habit is as hard to break as a bad one..

  5. #5
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    Overcomplicating

    Quote Originally Posted by danl1
    Square tires? Might as well use a random number generator. It should be the volume of the two toroids that we're comparing.
    It may come as a shock to you, but all you have to do is compare the cross sectional areas of the two different tires, and since that is proportional to the square of the diameter, all you have to do is ratio the squares of the diameters, which is exactly what I did. You went through all that and got the EXACT same answer that I did with a simple ratio. It helps when you actually understand the geometry instead of just whipping out formulae

  6. #6
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    Quote Originally Posted by Kerry Irons
    It may come as a shock to you, but all you have to do is compare the cross sectional areas of the two different tires, and since that is proportional to the square of the diameter, all you have to do is ratio the squares of the diameters, which is exactly what I did. You went through all that and got the EXACT same answer that I did with a simple ratio. It helps when you actually understand the geometry instead of just whipping out formulae
    Guys, I go to a "Laboratory High School" for "academically talented students"
    It's otherwise known as nerd-heaven. 3 years ago the guys on the basketball team were trading calculator games. We have a manga club. We have a Lord of the Rings club. We have everything nerdy in the world.

    And I'm still shocked by how geeky you two are being
    eek.
    "It's hard to tell the poison from the cure, so enjoy the disease."
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  7. #7
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    Nice estone -

    That actually made me LOL...

  8. #8
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    You ain't seen nothing yet

    Quote Originally Posted by estone2
    Guys, I go to a "Laboratory High School" for "academically talented students" It's otherwise known as nerd-heaven.
    Ha! Try going to engineering school. Especially a university where it has Technology or Technological in the title. Your nerd heaven ain't nothing. BTW, nerd heaven is not hyphenated

  9. #9
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    Quote Originally Posted by Kerry Irons
    BTW, nerd heaven is not hyphenated
    Your point is moot without citations.
    I do not know of any conventions on the hyphenation or lack thereof of nerd-heaven/nerd heaven

    Would nerd haven be more appropriate? I think it would be, as a haven is a safe place. At a public school, my entire school would get beat up within minutes... we'd have no lunch money for years
    At my school, velcro shoes and black socks are cool!
    (Well, okay we're not that bad. But a couple kids do do that...)

    -estone2
    "It's hard to tell the poison from the cure, so enjoy the disease."
    -Mohair_Chair

  10. #10
    Steaming piles of opinion
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    Quote Originally Posted by Kerry Irons
    It may come as a shock to you, but all you have to do is compare the cross sectional areas of the two different tires, and since that is proportional to the square of the diameter, all you have to do is ratio the squares of the diameters, which is exactly what I did. You went through all that and got the EXACT same answer that I did with a simple ratio. It helps when you actually understand the geometry instead of just whipping out formulae
    Exact? Dude, you were like 0.4PSI off!!! Imagine what that would do to ride quality! There'd be pinch flats all over the place!! Tires would be rolling right off the rims! Oh, the humanity!! You are a danger to riders everywhere!!!

    (As with the initial post, this is tongue in cheek.)

    To indulge the inner geek, your method only works because of the relatively small difference between the sizes. With an absurd tire size difference, the increase of the major radius would increase the volume a fair bit, which is the cause of the slight difference in our calculations. We could prove it, but not without invoking Leibniz, and my, how I hate that bugger. Besides, I'm to stoopid to figger out integral notation on internet forums.

    Of course you know that and know that it's not meaningful, which is why the smiley was in the first post.
    A good habit is as hard to break as a bad one..

  11. #11
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    Enough to ride home on.
    If your opinion differs from mine, ..........Too bad.
    .
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    Dogbert.

    I>U

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  12. #12
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    Finally, the practical response. That's all I care about too..... and if one CO2 cartridge isn't enough, that's why I always carry two.

  13. #13
    n00bsauce
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    Yeah, and a 12g cartridge is enough for a 700x23c tire.
    "Those who can make you believe absurdities can make you commit atrocities." Voltaire

    There are your fog people & your sun people, he said. I said I wasn't sure which kind I was. He nodded. Fog'll do that to you, he said.

    "We are all ignorant about most things."
    Mel Erickson

  14. #14
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    A 12g will also get you home, on a 28mm tire, if you ride carefully........(.80 psi????????)
    If your opinion differs from mine, ..........Too bad.
    .
    How would you like it if Hitler killed you
    Dogbert.

    I>U

    Buying parts to hang on your bike is always easier than getting fit.

    If you feel wimpy and weak, get out and train more, ya wee lassie!

    If Jesus had a gun, he'd be alive today!

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