# Helium in tires = Lighter?



## Elpimpo (Jan 16, 2012)

Cheap way to save weight?


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## LuckyB (Sep 9, 2012)

That will do it, or take a good dump before you ride.


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## qwertasdfg24 (Sep 18, 2012)

I believe there is a helium shortage nationally going on...good luck finding reasonably priced helium.


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## testpilot (Aug 20, 2010)

Mercury vapor = bling.


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## Canndyman (Sep 7, 2012)

I'm not a scientist, and I don't have a periodic chart of the elements in front of me, but If I'm not mistaken helium is the second smallest molecule behind hydrogen. What that means to you is your tires are going to lose pressure with helium way faster than with air. While we can't see it with our naked eyes, tubes are porous no matter what they are made out of. Helium will find it's way out. Latex ballons don't last long with helium. Mylar ballons do much better. I don't think you will see any difference on a scale. Pure inert gases are more stable than air, hence why some places offer nitrogen for filling tires (automotive) now. Hope that helps.....


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## redondoaveb (Jan 16, 2011)

Doesn't work. I tried it with my bike, it floated away. Hope it comes down in a neighbors tree like all my balloons did when I was a kid.


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## Canndyman (Sep 7, 2012)

If you really want to see for yourself, do this. Find a local store that sells helium balloons. Easy to do. Most grocery stores sell them that have floral departments. If thats a no go, find a Party America, Party City, or Hallmark store. Birthday/get well balloons are easy to find. Buy one balloon inflated with helium, and one not. When you get home to your gram scale, inflate the second balloon by mouth to the same size as the helium balloon. Put a little piece of tape on your scale to hold the balloon in place and weigh each. I doubt your going to see much difference.
If you decide you want to go for it here's what your going to have to do. Find a local welding supply shop, most sell common inert gasses as well as acetelyne (they will sell helium as it's used for true "heliarc" welding). You'll have to create an account because you lease the cylinder, but buy the gas. Probably going to cost you over $100 to do both. Then you need to buy a regulator, full cylinders are pressurized to 2,500psi, probably going to pop your tires. Figure at least $100 for a regulator with gauges, then you'll need to adapt a hose and air chuck on it. Your going to get into this for several hundred dollars. Do the balloon test, and let us know if it's worth it. Good Luck~
I just thought of something.....the helium balloon is going to want to fly away. See, I don't know it all.......


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## Guest (Nov 21, 2012)

You can actually calcualte this pretty easily:


The "weight" of helium is about -1g / liter. Let's say that you usually inflate your tires to 105 PSI, or 7 atmospheres. You have 2 tires.

Your inner tube is essentially a Torus. Volume of a torus is given by: 2pi^2 * r^2 * R, where R is the radius of the wheel (let's say 35cm), and r is the radius of the inflated tube (let's say 1.2cm).

Weight savings is: (2 wheels) * (atmospheres of pressure) * (volume of tube) * (-1g/1000 cc)

About 18 grams.

Keep in mind if you were to fill both your empty water bottles with helium, instead of air, you'd save an additional 1.5 grams of weight. 

If you really wantd to get creative, you could actually make the hollow frame of the bike air tight and fill the whole frame with Helium. Although the weight of the additional gaskets and valve hardware would probalby offset the weight savings. Plus you'd have to re-fill your frame every time you change your seat post height.


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## tihsepa (Nov 27, 2008)

PhotonFreak said:


> You can actually calcualte this pretty easily:
> 
> 
> The "weight" of helium is about -1g / liter. Let's say that you usually inflate your tires to 105 PSI, or 7 atmospheres. You have 2 tires.
> ...


/thread

I think he make this crap up but am not smart enough to find out. :thumbsup:


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## aliensporebomb (Jul 2, 2002)

I figure if I lost 25 pounds or even 10 pounds it would make a bigger difference.


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## NJBiker72 (Jul 9, 2011)

You guys are not thinking big enough. Hydrogen is even lighter than Helium. Look how well it worked in the Hindenburg.

Just be careful breaking on sharp descents.


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## Elpimpo (Jan 16, 2012)

I was laughing as I originally posted this
Some funny/scientific stuff here

So, helium tires & bottles were down (up?) 21 grams
But what if I fill the whole frame with it?
I could use silicone sealant or epoxy to seal any leaks.

Dudes, I think we're onto something here, this is the future

Lets get stoopid with this one


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## nOOky (Mar 20, 2009)

I am thinking of building a fully enclosed recumbent bike and sealing the cockpit and filling it with helium. Preliminary calculations suggest a net weight savings of 145 grams. The only downside is talking funny while I am pedaling far as I can tell.


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## dougclaysmith (Oct 17, 2009)

When they were testing the SR71 Blackhawk aircraft, they were so desperate to dump as much weight as possible they tinkered with using helium in the tires. 

after further testing, they figured it was not with the hassle. (Skunk Work, Ben Rich)

And those guys were working on national security, not a Sunday ride.


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## carlosflanders (Nov 23, 2008)

I believe it was common to use helium in tires for TTs in the early 80s. I think the US used it for team TTs in pan American games and worlds. Will try to find a reference.


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## Guest (Nov 27, 2012)

carlosflanders said:


> I believe it was common to use helium in tires for TTs in the early 80s. I think the US used it for team TTs in pan American games and worlds. Will try to find a reference.


This is probably a moot point nowadays with most TT bikes landing right around the 6200g limit, and in some cases needing to add extra ballast weight to be race-legal. 

I'd also expect helium to leak out a lot faster compared to dry air or nitrogen-filled tires. Marginal risk of getting a flat (and ensuing time delay) likely far outweighs any weight benefits.


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## RJP Diver (Jul 2, 2010)

nOOky said:


> I am thinking of building a fully enclosed recumbent bike and sealing the cockpit and filling it with helium. Preliminary calculations suggest a net weight savings of 145 grams. The only downside is talking funny while I am pedaling far as I can tell.


That, and passing out from hypoxia after about 90sec and, shortly thereafter, dying.

But weight is weight, right?


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## .je (Aug 25, 2012)

Canndyman said:


> I'm not a scientist, and I don't have a periodic chart of the elements in front of me, but If I'm not mistaken helium is the second smallest molecule behind hydrogen. What that means to you is your tires are going to lose pressure with helium way faster than with air. .....


Probably very true... it's also true that even thought CO2 is a much larger molecule that both O2 and N2, its solubility in butyl rubber is greater than both those gases - which is another reason why it isn't used to inflate any kind of tire, even aircraft.


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## tihsepa (Nov 27, 2008)

nOOky said:


> I am thinking of building a fully enclosed recumbent bike and sealing the cockpit and filling it with helium. Preliminary calculations suggest a net weight savings of 145 grams. The only downside is talking funny while I am pedaling far as I can tell.


Remember, you need a beer gut and beard for a bent. Dont forget the sandals. 

Nobody will care if you talk funny. You are riding a funny little machine anyway.


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## Oxtox (Aug 16, 2006)

using He to inflate tires is a waste of the gas.

since it's getting more and more scarce, it should be reserved for proper purposes such as welding, diving, and assisted suicide.

Helium hood method now the way for assisted suicide | Assisted-Dying Blog


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## ratherBclimbing (Apr 2, 2007)

Oxtox said:


> using He to inflate tires is a waste of the gas.
> 
> since it's getting more and more scarce, it should be reserved for proper purposes such as welding, diving, and assisted suicide.
> 
> Helium hood method now the way for assisted suicide | Assisted-Dying Blog



I'm going to put medical uses (e.g. MRIs) well ahead of all those, and personally I'd put particle physics research up there as well, but that's because I think it's nifty.


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## asdasd44 (Apr 24, 2007)

This seems to come up often, hopefully this settles it: 










I'm too lazy to double check the numbers, someone else do it :idea:

Oh yea, this is for 1 tube, so double it for a bike for 14 grams which is close to what photonfreak estimated


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## SauronHimself (Nov 21, 2012)

Even with a high-pressure tire the mass of the helium will be so close to the mass of oxygen at the same PSI that you'll wonder why you wasted your money. Moreover, as others have mentioned before, the He2 molecule is much smaller and will permeate through your tires much more quickly, thereby losing pressure much more quickly. If you wanted to spend money on gas for your tires, you might try nitrogen since that molecule is larger than the O2 molecule and won't permeate as quickly.


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## testpilot (Aug 20, 2010)

SauronHimself said:


> Even with a high-pressure tire the mass of the helium will be so close to the mass of oxygen at the same PSI that you'll wonder why you wasted your money. Moreover, as others have mentioned before, the He2 molecule is much smaller and will permeate through your tires much more quickly, thereby losing pressure much more quickly. If you wanted to spend money on gas for your tires, you might try nitrogen since that molecule is larger than the O2 molecule and won't permeate as quickly.


Troll farts are far superior to "He2".


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## r1lee (Jul 22, 2012)

PhotonFreak said:


> You can actually calcualte this pretty easily:
> 
> 
> The "weight" of helium is about -1g / liter. Let's say that you usually inflate your tires to 105 PSI, or 7 atmospheres. You have 2 tires.
> ...


Well I'm no scientist, but if you fill both your water bottles up with helium, wouldn't you save more considering they aren't full of water?


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