Seems the new trend for autos now is to inflate your tires with Nitrogen. The Auto racing world has been doing it for years, and supposedly it lasts longer than oxygen.
I figure it can't be cheap and the benefits on a bicycle can't be much (if any), kind of interesting though

Anybody used it on their bike yet or know of any other facts about this?

google it. for car racing that heats up the tires much more than regular driving (or riding your bike, for that matter), it makes sense since N2 expands less and therefore changes the tire's pressure less, which is critical in auto racing applications. regular joe driver won't see the benefit since car tires under normal conditions (probably 99.99% of the driving we all do) don't change temperature enough to alter the pressure so much that the gas mileage would be significantly effected. it certainly won't offset the cost to put N2 in your tires.
search on google for all the info you care to know about this topic

Well, I doubt anyone fills their tires with oxygen since it's highly flammable. You probably mean compessed air. Using Nitrogen really has no more benefit to performance than compessed air other than there's no moisture in it. Nitrogen is a high pressure gas that comes in high pressure cylinders at about 1500-1800 PSI, so when using it to fill tires, you'll need a special regulator to control pressure. As for why they use it in the Auto racing world... I can olny guess is allot faster to pressurize tires... I guess if you want any advantage, try helium

Yes, I Googled it and yes I meant compressed air (sorry) instead of oxygen, but I was just wondering if anyone on VBMX has actually done it or not.

I have always wondered about Helium inflation myself...

The methanol drag rail I help out with uses Nitrogen from their weldeing tanks rather than normal compressed air to inflate both the inner tubs of each rear slick.

As mentioned the Nitrogen out of the tank is clean & has no moisture or other contaminents in it rather than using the dirty inconsistant ~70% Nitrogen & ~30% Oxygen mix you get out of a filtered air compressor. Running straight nitrogen also makes the slicks more reliable & predictable as far as keeping the heat in them after the burnout.
It's just one of those little "tricks" you do in motor sport when your running a car that does <5.5 second 1/4 @ > 250 MPH and every 1/1000th of a second you can get over the opposition counts.
I've also seen air tools being run off nitrogen cylinders in the pits at race meets due to lack of power or insufficient power being available , trying to start a single phase compressor motor @ 200VAC under load instead of the 240VAC required tends to burn out the electric motors windings very quickly after only a few startups. Instant panic sets in when there's no compressed air available in the pits on race day.

Hydrogen would be your best bet for light wheels over Helium. You won't end up with a Hindenburg style distater if they do manage to ignite , just a louder than usual bang , but no severe burns to yourself , Hydrogen burns _really_ fast when ignited & dispurses into the air very rapidly into a non flammable mix should you get a puncture. Your more likely to blow yourself up after you have seperated the H from the O & are trying to compress it into a holding tank. I'm not too sure as to the long term effects of using Hydrogen in rubber inner tubes tho.

Overall , I think the only bicycle people who _might_ benefit from messing around with what sort of gas they put into their tires are the shaved leg road & track boys , who as we all know will use every trick in the book they can get away with to get an edge on the competition using the basic 375 watt/hour powerhouse that the human body is in peak condition.

Probably best to leave the fancy air in the tires for the guys who have the big HP available to them & race around tacks longer than 400 meters...powering air tools with compressed Nitrogen or any other inert gas can always be used to get you outta troble , when the power drops out

JB

Airplanes require nitrogen in the tires of most high-altitude aircraft because the water in the compressed air comes out of suspension at altitude and causes out-of-balance problems. (This is why you shouldn't use scuba oxygen in aircraft oxygen tanks as well; it freezes up at high altitude)

I could see why it would work well for cars also, since the water vapor problem makes it more sensitive to heat. On bicycles, I don't see it as making much of a difference.

I used to ride my road bike to work and dutifully service the tires with nitrogen every couple of days or so and it worked as well as it worked, but really you couldn't tell the difference from compressed air service: Bicycles don't go high enough or go through the temp extremes to their being a real benefit, I'm saying.

I'm going off hearsay from a LONG time ago; I think nitrogen might be larger molecularly (is that a word?), which makes it harder to pass through the pores of a tire/tube. It holds pressure longer. I'm sure someone will verify that 'cause I'm too lazy...

It works great in suspension for all the reasons mentioned...

Everyone fills their tires with Nitrogen. ...80% Nitrogen anyway.

The air we breathe is about 78% nitrogen, 21% oxygen, .3% carbon dioxide and traces of helium, neon, other gases and water vapor. No matter how much you compress it, or at what altitude, the ratio stays the same. (why you can't breath up high is because of pressure, not ratio)

It all boils down to heat and moisture when deciding to use Nitrogen.

Aircraft brakes get VERY hot, VERY quickly, and so do the tires. (and they are very cold to start with, coming down from altitude). ....Errrrt. They can go from -40F to hundreds of degrees (almost red hot) in less than 10 seconds. In an emergency, they will go red hot, and even catch fire.

Moisture makes steam when hot, and water droplets when cool, which, with oxygen, causes corrosion on the rims, and fungus and rot inside the tires too. Especially with Magnesium rims.

Pure DRY Nitrogen eliminates that. That's why you use 200-PSI Nitrogen in your Fox Shox. IE...On a snowmobile you get ice inside the shock metering ports and they don't work, then they get hot when you start pounding on them, then they cool, you get water under the oil, corrosion on the shaft, ice in the metering holes, etc...

Heat, moisture, corrosion, bacteria, etc... (The coefficient of expansion of pure Nitrogen Vs. a Nitrogen/Oxygen/Water mix is a valid racing thing too)

Pure dry Nitrogen on the inside an inner tube on a bicycle? Silly waste of time and money.

BTW, Oxygen isn't flamable, it will NOT burn, it only helps fuels burn.

PS, I miss being an aircraft mechanic. I'm reminded at times like this of how much I wish I could get back into it. Ahh, the contempt I hold for the airline execs tossing all the talent and knowledge into the streets, and farming aircraft maintenance to the unskilled cheap labor fields overseas....~~~~Sigh~~~~ What a waste of knowledge, trained people, and talent.....

~~~~Goes back to looking for a new career on the internet job boards~~~~

[ June 08, 2007, 04:18 AM: Message edited by: Ted Carl ]

Ted,

Too bad the "Ambassador of VBMX Restoration" doesn't pay as much as it sounds like it would.

Just remember who nominated you in the first place.

Mike

Ted,
I never get sick of listening to your entertaining tech explanations and tips. Thanks mate. You da man.
Cheers
Kurt

Great Stuff Ted! I feel that I am starting off my day a bit smarter!

http://www.liveleak.com/view?i=921_1179536523

Try this with a 36 spoke araya....

The clip expolits the trump card, as to why Oxygen is NOT welcome in some tires.

Although some of our arses are getting pretty big, I still don't think we are capable of heating a graphite tuff quite like that.....even on a really big hill...lol

Cheers.

To all of you suggesting hydrogen or helium, keep in mind that what makes them lighter than air (that 70/30 mix mentioned above) also makes them a smaller molecule. That translates to your tires going flat sooner than with a denser gas.

quote:

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Hydrogen would be your best bet for light wheels over Helium. You won't end up with a Hindenburg style distater if they do manage to ignite , just a louder than usual bang , but no severe burns to yourself , Hydrogen burns _really_ fast when ignited & dispurses into the air very rapidly into a non flammable mix should you get a puncture. Your more likely to blow yourself up after you have seperated the H from the O & are trying to compress it into a holding tank. I'm not too sure as to the long term effects of using Hydrogen in rubber inner tubes tho.

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The Hindenburg was filled with hydrogen, and helium is non-flammable.

Here's some links...
Hindenburg