Helium in tyres for weight weenies...
11-02-09, 06:28 PM
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Helium in tyres for weight weenies...
Hi all
Was just playing around with some figures:
140.00 PSI for tyres
1.20 kg/m3 weight of air at 1 bar (14.5 PSI) - sea level - 20 degrees C
0.17 kg/m3 weight of helium at 1 bar (14.5 PSI) - sea level - 20 degrees C
1.00 cm tube radius
70.00 cm wheel diameter
219.91 cm wheel circumference
1381.74 cubic cm
0.00138 cubic m
16.06 weight of air in grams in tyre
2.22 weight of helium in grams in tyre
27.69 weight saving in 2 tyres
So - you could make your bike lighter by about an ounce by swapping from regular air to helium. Additionally, this is at the outside of the wheel, where it takes the most work to move it, so acceleration would be higher.
Helium however would leak out of the tyres more quickly, needing to be topped up before every race.
Was just playing around with some figures:
140.00 PSI for tyres
1.20 kg/m3 weight of air at 1 bar (14.5 PSI) - sea level - 20 degrees C
0.17 kg/m3 weight of helium at 1 bar (14.5 PSI) - sea level - 20 degrees C
1.00 cm tube radius
70.00 cm wheel diameter
219.91 cm wheel circumference
1381.74 cubic cm
0.00138 cubic m
16.06 weight of air in grams in tyre
2.22 weight of helium in grams in tyre
27.69 weight saving in 2 tyres
So - you could make your bike lighter by about an ounce by swapping from regular air to helium. Additionally, this is at the outside of the wheel, where it takes the most work to move it, so acceleration would be higher.
Helium however would leak out of the tyres more quickly, needing to be topped up before every race.
11-02-09, 06:47 PM
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Originally Posted by PetesDustyVolvo
I nominate this for stupidest thread of all time.
NOTE TO THE OP: This does not validate your thread. it just points out how stupid the other stupid threads are. your thread is pretty stupid.
11-02-09, 06:48 PM
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Only Freds use helium. Real men use hydrogen. Another secret: I plug up all the holes in my frame and pull a vacuum on the inside. Big time weight savings, dude.
11-02-09, 06:54 PM
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Originally Posted by lambo_vt
Only Freds use helium. Real men use hydrogen. Another secret: I plug up all the holes in my frame and pull a vacuum on the inside. Big time weight savings, dude.
Only nominal savings in weight moving from helium to hydrogen:
140.00 PSI for tyres
1.20 kg/m3 weight of air at 1 bar (14.5 PSI) - sea level - 20 degrees C
0.09 kg/m3 weight of hydrogen at 1 bar (14.5 PSI) - sea level - 20 degrees C
1.00 cm tube radius
70.00 cm wheel diameter
219.91 cm wheel circumference
1381.74 cubic cm
0.00138 cubic m
16.06 weight of air in grams in tyres
1.19 weight of hydrogen in grams in tyres
29.75 weight saving in tyres
A little bit upset that I am disqualified for a thread prize for good math!
11-02-09, 06:58 PM
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funny, i think this has been brought up before. someone brought up that helium would leak out of the tires too quickly. not sure where they came up with that, but you're clearly into researching this so go check it out.
11-02-09, 06:59 PM
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Originally Posted by tallmantim
LOL
Only nominal savings in weight moving from helium to hydrogen:
140.00 PSI for tyres
1.20 kg/m3 weight of air at 1 bar (14.5 PSI) - sea level - 20 degrees C
0.09 kg/m3 weight of hydrogen at 1 bar (14.5 PSI) - sea level - 20 degrees C
1.00 cm tube radius
70.00 cm wheel diameter
219.91 cm wheel circumference
1381.74 cubic cm
0.00138 cubic m
16.06 weight of air in grams in tyres
1.19 weight of hydrogen in grams in tyres
29.75 weight saving in tyres
A little bit upset that I am disqualified for a thread prize for good math!
Only nominal savings in weight moving from helium to hydrogen:
140.00 PSI for tyres
1.20 kg/m3 weight of air at 1 bar (14.5 PSI) - sea level - 20 degrees C
0.09 kg/m3 weight of hydrogen at 1 bar (14.5 PSI) - sea level - 20 degrees C
1.00 cm tube radius
70.00 cm wheel diameter
219.91 cm wheel circumference
1381.74 cubic cm
0.00138 cubic m
16.06 weight of air in grams in tyres
1.19 weight of hydrogen in grams in tyres
29.75 weight saving in tyres
A little bit upset that I am disqualified for a thread prize for good math!
11-02-09, 07:03 PM
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helium in tires done by the american road team at the 1984 olympic games in LA.
11-02-09, 07:08 PM
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How many times are we gonna re-visit this before someone posts "We've looked at this, it's not worth it."
But I did like the Hydrogen in the tubes idea, sort of like a mini-Hindenburg.
But I did like the Hydrogen in the tubes idea, sort of like a mini-Hindenburg.
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11-02-09, 07:16 PM
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Originally Posted by lambo_vt
Nominal??! Hydrogen provides 50% less weight in the tires vs. helium. 50%! That ain't nominal -- HTFU!
11-02-09, 07:17 PM
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Originally Posted by kudude
Sure, but you get about a factor of ten going from N2 to He2.......this means you are down to 10% of the original. Going to 5% is only a couple of grams. It's all about how you "play" the numbers. It's nominal
11-02-09, 07:28 PM
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Originally Posted by tallmantim
Hi all
Was just playing around with some figures:
140.00 PSI for tyres ...
Was just playing around with some figures:
140.00 PSI for tyres ...
11-02-09, 07:35 PM
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Dude, you are so on to something ! I never thought of it till you mentioned it, but why not attach balloons to your bike? In fact, why not attack 200-500 weather balloons? Your bike will be so light you'll fly like a jet.................(or at least jets will pass you as you fly up) I'm not sure, but I think it might have been tried already
Last edited by yohimbe2; 11-02-09 at 07:38 PM.
11-02-09, 07:36 PM
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Originally Posted by tc83
funny, i think this has been brought up before. someone brought up that helium would leak out of the tires too quickly. not sure where they came up with that, but you're clearly into researching this so go check it out.
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11-02-09, 07:45 PM
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i think your math is off. The volume of the tube = C x (cross sectioanl area of the tube)
=(2.199m)(3.142x10^-4m) = 6.908x10^-4 m^3
You also cannot use the kg/m^3 values because the denisty is pressure dependent. You need to find the number of moles of gas, and then use molecular weight to convert to actual mass.
P= 140PSI= 9.52 atm= 10.52 atm abs.= 1065939 Pa abs.
T=20*C=293K
V=6.908x10^-4 m^3
R=8314 (m^3)(Pa)/(kmol)/(K)
PV/R/T=n
n= 3.023x10^-4 kmol = 0.3023 mol
mw Air= 14.5g/mol (O2,N2)
Mass air in a tire= 5.44 g/ wheel
Mass helium in a tire= 0.605g/wheel
=(2.199m)(3.142x10^-4m) = 6.908x10^-4 m^3
You also cannot use the kg/m^3 values because the denisty is pressure dependent. You need to find the number of moles of gas, and then use molecular weight to convert to actual mass.
P= 140PSI= 9.52 atm= 10.52 atm abs.= 1065939 Pa abs.
T=20*C=293K
V=6.908x10^-4 m^3
R=8314 (m^3)(Pa)/(kmol)/(K)
PV/R/T=n
n= 3.023x10^-4 kmol = 0.3023 mol
mw Air= 14.5g/mol (O2,N2)
Mass air in a tire= 5.44 g/ wheel
Mass helium in a tire= 0.605g/wheel
11-02-09, 07:47 PM
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Originally Posted by lambo_vt
Dude, 50% though!!! HTFU!!!!!!!
11-02-09, 07:50 PM
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I was just about to bring this up, but you beat me to it.
I mean, duh. How stoopid are cyclists.
I mean, duh. How stoopid are cyclists.
Originally Posted by enjoi
i think your math is off. The volume of the tube = C x (cross sectioanl area of the tube)
=(2.199m)(3.142x10^-4m) = 6.908x10^-4 m^3
You also cannot use the kg/m^3 values because the denisty is pressure dependent. You need to find the number of moles of gas, and then use molecular weight to convert to actual mass.
P= 140PSI= 9.52 atm= 10.52 atm abs.= 1065939 Pa abs.
T=20*C=293K
V=6.908x10^-4 m^3
R=8314 (m^3)(Pa)/(kmol)/(K)
PV/R/T=n
n= 3.023x10^-4 kmol = 0.3023 mol
mw Air= 14.5g/mol (O2,N2)
Mass air in a tire= 5.44 g/ wheel
Mass helium in a tire= 0.605g/wheel
=(2.199m)(3.142x10^-4m) = 6.908x10^-4 m^3
You also cannot use the kg/m^3 values because the denisty is pressure dependent. You need to find the number of moles of gas, and then use molecular weight to convert to actual mass.
P= 140PSI= 9.52 atm= 10.52 atm abs.= 1065939 Pa abs.
T=20*C=293K
V=6.908x10^-4 m^3
R=8314 (m^3)(Pa)/(kmol)/(K)
PV/R/T=n
n= 3.023x10^-4 kmol = 0.3023 mol
mw Air= 14.5g/mol (O2,N2)
Mass air in a tire= 5.44 g/ wheel
Mass helium in a tire= 0.605g/wheel
11-02-09, 08:20 PM
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Originally Posted by lambo_vt
Nominal??! Hydrogen provides 50% less weight in the tires vs. helium. 50%! That ain't nominal -- HTFU!
hydrogen as a gas is H2 so it is approximately the same weight as helium. if you are building a blimp or dirigible the have roughly the same lifting power
11-02-09, 08:27 PM
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Originally Posted by zzzwillzzz
fail.
hydrogen as a gas is H2 so it is approximately the same weight as helium. if you are building a blimp or dirigible the have roughly the same lifting power
hydrogen as a gas is H2 so it is approximately the same weight as helium. if you are building a blimp or dirigible the have roughly the same lifting power
11-02-09, 08:41 PM
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I can see filling ones tires with He, then about an hour later, riding home on flat tires.
(The Helium molecule is so small, it literally leaks right through the butyl rubber.)
(The Helium molecule is so small, it literally leaks right through the butyl rubber.)
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11-02-09, 09:24 PM
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Originally Posted by tallmantim
Hi all
Was just playing around with some figures:
140.00 PSI for tyres
1.20 kg/m3 weight of air at 1 bar (14.5 PSI) - sea level - 20 degrees C
0.17 kg/m3 weight of helium at 1 bar (14.5 PSI) - sea level - 20 degrees C
1.00 cm tube radius
70.00 cm wheel diameter
219.91 cm wheel circumference
1381.74 cubic cm
0.00138 cubic m
16.06 weight of air in grams in tyre
2.22 weight of helium in grams in tyre
27.69 weight saving in 2 tyres
So - you could make your bike lighter by about an ounce by swapping from regular air to helium. Additionally, this is at the outside of the wheel, where it takes the most work to move it, so acceleration would be higher.
Helium however would leak out of the tyres more quickly, needing to be topped up before every race.
Was just playing around with some figures:
140.00 PSI for tyres
1.20 kg/m3 weight of air at 1 bar (14.5 PSI) - sea level - 20 degrees C
0.17 kg/m3 weight of helium at 1 bar (14.5 PSI) - sea level - 20 degrees C
1.00 cm tube radius
70.00 cm wheel diameter
219.91 cm wheel circumference
1381.74 cubic cm
0.00138 cubic m
16.06 weight of air in grams in tyre
2.22 weight of helium in grams in tyre
27.69 weight saving in 2 tyres
So - you could make your bike lighter by about an ounce by swapping from regular air to helium. Additionally, this is at the outside of the wheel, where it takes the most work to move it, so acceleration would be higher.
Helium however would leak out of the tyres more quickly, needing to be topped up before every race.
cool story bro.
