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  1. #1
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    how much weight does air pressure add

    I have a Titus Racer X which is a fairly light bike.

    If I add 40psi to the tires (Hutchinson Pythons, but is tire make/model relevant?) then how much total weight would this add to the bike?

    Also, how much does tire air pressure counter the weight advantages of a bike? Does the weight added to the tires through air pressure impact performance less than if this extra weight was in the frame? Or does this make no difference?

  2. #2
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    is this a joke?
    affect befect cefect defect effect fect

  3. #3
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    Quote Originally Posted by scottzg
    is this a joke?
    LOL..

  4. #4
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    i fill my tires with mt. dew

  5. #5
    I bought some roadies.
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    Idea!

    Jolt cola has more caffeine try that. Or just go big and fill those beasts with red bull. It'll give you wings.

  6. #6
    wuss
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    You really want to fill those tires with helium, and put as much as you can. With helium the bike goes over rough sections much smoother, jumps higher and lands softer.

  7. #7
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    Meh..Just fill it with beer!!! That way when you get a flat you can drink the left over beer and you won't be as angry about fixing the flat.
    If your worried about the extra weight use a light beer...

  8. #8
    Ride the dream
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    Quote Originally Posted by titus
    I have a Titus Racer X which is a fairly light bike.

    If I add 40psi to the tires (Hutchinson Pythons, but is tire make/model relevant?) then how much total weight would this add to the bike?

    Also, how much does tire air pressure counter the weight advantages of a bike? Does the weight added to the tires through air pressure impact performance less than if this extra weight was in the frame? Or does this make no difference?
    Ignore the weight, its such a tiny difference you wouldnt notice it.


    The real question in, WHY would you want to add that much?


    You might want to read About Rolling Resistance

    In simple terms, adding so much air that the tyre is almost SOLID will result in more resistance - harder work to pedal, and slower times - while at the same time providing less grip (basically because instead of shifting shape on uneven ground, it instead has to bump over it).

    The article is rather useful, and definately worth reading.

  9. #9
    Keep pedaling
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    Maybe this will help. According to Mythbusters:

    * air in a football weighs about 3.2 grams.
    * helium-filled footballs are 7 grams lighter than an air-filled one.
    * helium-filled footballs are lighter than an empty football by about 1%.

    http://kwc.org/mythbusters/2006/02/m..._a_bullet.html

  10. #10
    EDR
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    Quote Originally Posted by Furball the Mystery Cat
    Maybe this will help. According to Mythbusters:

    * air in a football weighs about 3.2 grams.
    * helium-filled footballs are 7 grams lighter than an air-filled one.
    * helium-filled footballs are lighter than an empty football by about 1%.

    http://kwc.org/mythbusters/2006/02/m..._a_bullet.html
    ...and in their tests He filled footballs traveled no further than air filled footballs.

    The OP's question is joke, at least hope so

  11. #11
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    What if the world he is riding in has a helium atmosphere?

  12. #12
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    I hate to jack this awesome thread, but I wonder if I could install a valve to fill my frame with helium?

  13. #13
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    I find a 16g CO2 cartridge is sufficient to inflate my tyres. Air, being 79% N2 has a molecular mass close to 23% lighter than pure CO2, so just over 12g of air should be sufficient (that is per tyre).

    The OP misses the obvious answer for lowering the required mass of air for tyre inflation, which is to restrict riding to high altitude venues.

  14. #14
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    I declare you king of the weight wennies

  15. #15
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    Quote Originally Posted by Tim Mailloux
    I declare you king of the weight wennies

  16. #16
    NICE KID...NICE
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    take a big sh!t before you ride...

    That will counter act any air you put in your tires...
    "At that point man, your just riding your bike."


    Transition


    Pedalshop

  17. #17
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    Quote Originally Posted by wookie freeride
    That will counter act any air you put in your tires...
    So will emptying the lint out of your pockets, or shaving your legs.

    OP, if you want the lightest wheels possible, have you taken the decals off yet? What about sanding the paint off?

  18. #18
    Taco Flavored Kisses
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    Hahaha

    Hey, maybe his air is realllly cold. 40 PSI of near freezing air might weight 3, maybe 4 pounds in a tire.... until is warmed up and your wheels exploded.


  19. #19
    don't thread on me
    Reputation: Roswell52's Avatar
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    Quote Originally Posted by titus
    I have a Titus Racer X which is a fairly light bike.

    If I add 40psi to the tires (Hutchinson Pythons, but is tire make/model relevant?) then how much total weight would this add to the bike?

    Also, how much does tire air pressure counter the weight advantages of a bike? Does the weight added to the tires through air pressure impact performance less than if this extra weight was in the frame? Or does this make no difference?
    Just take a leak before you ride and it will offset the weight gain from AIR.....
    sign here ________________________

  20. #20
    Alien Surf Team
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    Hydrogen, people... hydrogen.

  21. #21
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    Quote Originally Posted by MFDOOM
    Hahaha

    Hey, maybe his air is realllly cold. 40 PSI of near freezing air might weight 3, maybe 4 pounds in a tire.... until is warmed up and your wheels exploded.

    he wouldnt be ALIVE to ride his bike...no joke....
    he freezes at -700 somn F....the last element to freeze in the atmosphere we breathe
    Lean back, Hit both brakes, And ask yourself, Do you feel lucky today?

  22. #22
    trail addict
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    If you are worried about the extra weight of 40 psi in the tires, just drain your 15 wt fork oil and add 5 wt instead. Difference = 10 x 2 (fork legs) = 20, so that saves the weight you gained on the tires right there (assuming 30 psi to 40 psi, difference = 10 x 2 (tires) = 20), although the tires are rotating mass, so you have to square it.

    Sometimes your better off with more wait, though, it will pull you down hills faster.
    You better just go ahead and drop that seatpost down to the reflector... the trail gets pretty rough down there.

  23. #23
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    Quote Originally Posted by Uncle Six Pack
    .

    Sometimes your better off with more wait, though, it will pull you down hills faster.
    Until you reach terminal velocity. At that point the weight difference with less air may help with the bike control at 120mph (given zero drag coefficient)............

    T

  24. #24
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    What's that TV commercial where two guys are on bikes and one guy is riding an "air bike"? That would be the ultimate savings.

  25. #25
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    Pounds per square inch (psi), although it has the word pounds in it, is not a measure of weight, it's a measure of pressure. While this is fairly obvious, it's the only thing I could think of that would make this thread worth reading.

    On the topic of weight, are some people in such perfect physical condition that the only way to improve their time is to lose a gram or two off of the bike? Personally, I'd just ride naked.

  26. #26
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    Quote Originally Posted by mountainbiker24
    On the topic of weight, are some people in such perfect physical condition that the only way to improve their time is to lose a gram or two off of the bike? Personally, I'd just ride naked.
    That's what I always think. Shouldn't we work on losing the 10+ lbs on our guy first.

  27. #27
    Praise Bob
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    Dont know exactly why I am replying to this but...just wanted to point out another confusion in this thread. Filling your bike tyres with helium does not change the mass of the wheelset. You make them weight less because of helium's density compared to atmospheric air, but you didnt change the mass of the wheel. We normally confuse weight and mass because they are often used interchangably, but in this case they are very different beasts.

  28. #28
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    Quote Originally Posted by Razorfish
    That's what I always think. Shouldn't we work on losing the 10+ lbs on our guy first.

    if i could lose 10+ pounds on my guy... i don't think i could even sit on the bike seat.
    affect befect cefect defect effect fect

  29. #29
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    Quote Originally Posted by scottzg
    if i could lose 10+ pounds on my guy... i don't think i could even sit on the bike seat.
    Gut

  30. #30
    it's....
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    Obviously, the best way is just get strong rims and forget the tires altogether.
    That'll save 80 pounds of air besides the loss of tires and tubes weight.

  31. #31
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    Are you for real?

  32. #32
    Look at the time!
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    Quote Originally Posted by Spartacus Rex
    Dont know exactly why I am replying to this but...just wanted to point out another confusion in this thread. Filling your bike tyres with helium does not change the mass of the wheelset. You make them weight less because of helium's density compared to atmospheric air, but you didnt change the mass of the wheel. We normally confuse weight and mass because they are often used interchangably, but in this case they are very different beasts.
    I know what you mean, but this is not true. You do change the mass of the wheelset as well as the weight. Quite simply, air has a higher mass per volume than helium, so you can reduce the mass of an object by replacing air with helium. The mass of a tire filled with air is greater than the mass of a tire filled with helium, no matter if measured in a vacuum or inside the earths athmosphere.

    Now, does the gas in a tire count as rotating mass? Thats a whole other question...


    by the way, helium would save weight not only because of its smaller mass, but also because it would leak out of the tire within hours. That stuff is hard to contain.
    wanted: Cannondale Lefty w/ V-brake studs

  33. #33
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    Quote Originally Posted by Razorfish
    What's that TV commercial where two guys are on bikes and one guy is riding an "air bike"? That would be the ultimate savings.
    i think it was a capital one rewards credit card commercial, if i remember correctly. i couldn't tell if his air bike was xc or dh, though.

  34. #34
    it's....
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    Quote Originally Posted by monstey
    i think it was a capital one rewards credit card commercial, if i remember correctly. i couldn't tell if his air bike was xc or dh, though.
    He wiped out on a mild downhill, so had to be xc.

  35. #35
    Bicyclochondriac.
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    Quote Originally Posted by wookie freeride
    That will counter act any air you put in your tires...
    Heck, a fart will do the trick.

  36. #36
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    Quote Originally Posted by Razorfish
    Hydrogen, people... hydrogen.
    Crash and burn?

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