I was wondering if you could put anything other than air in your tires. Or if someone makes tires that can hold different things. I was mainly thinking Nitrogen or Helium. Or any combination.

A lot of people use CO2 I 'spose you could use nitrogen like NASCAR to get more consistency in pressure changes as the tires come up to temperature

Nitrogen - lol.

The local high-end shop sells nitrogen to put in tires. Its effects are only worth it on tubular racing wheels with very high pressures. The nitrogen helps to hold tire shape around corners. Scientifically it weighs less although in the real world such a small difference isn't easily measured.

Also, a note about filling your tires with CO2: sure it's great for quick changes without carting around a mini-pump. However, since CO2 does weigh just a tad bit more than air, and also since it doesn't absorb bumps as well as air, you should pump your tires back up with air when you get the chance.

No, nitrous oxide LOL!

Hydrogen

Thanks for the info.

Oh, the humanity...

Some people go so far as to fill their car tires, basketballs, soccer balls with pure nitrogen:
https://www.washingtonpost.com/wp-dyn...073100577.html

Maybe it has merits, but seems a tad bit silly to me. They claim to get slightly better gas mileage, but it's probably mostly because they're obsessing over their tires and filling them up more often than they would otherwise.

There was a thread on BF about a year ago where people were arguing about whether CO2 or Nitrogen, or whatever was the best thing to fill tires with. It went on for several pages and got quite heated. Finally somebody posted something like this:

Suddenly, everyone felt quite sheepish, and the thread died a peaceful death

We have a remote control blimp at work which we fly around the lab when we're bored and/or slacking. It was filled with helium, but started to sag a bit. Since we didn't have a dewar of helium handy, we topped it off with hydrogen...

Then we named the blimp Hindenberg Jr.

(Fortunately, it contains only a liter or two of hydrogen and it's mixed with helium. Don't try this one at home, kids.)

Years ago, Continental did some research on this. They found that using pure nitrogen gave the best result in terms of reducing rolling friction. But the differences were very small. If it weren't, teams at the big Pro tours would be seen filling tires from a bottle, not a pump.

This morning there was a sidebar on NPR about people filling their car tires with Nitrogen (alla Nascar as mentioned above) I forget the reference but they said that the cost was about 2-5 $ per tire, and that the savings added up to 1 m/ga. They didn't mention how often you would have to refill so the cost benifit is still a question. So I guess the idea is that if you filled your bicycle tires with nitrogen there would be an improvement in efficiency. Maybe I'll stop by the industrial gas supply place along my commute on the way home and give it a try.

This sounds absurd. 1 mpg improvement would be a 4 to 10% improvement in the mileage depending the car. Come on, this can't be serious.

Air is about 80% Nitrogen already and the physical properties of most gasses (certainly Oxygen and Nitrogen) at typical pressures and temperatures are nearly identical so there should be no demonstrable difference in compressibility or anything else. It sounds like NPR got suckered into doing a free ad for the Nitrogen sellers. If I could get $2-5 per tire, I'd lie too.

BTW, the problem with CO2 isn't it's "weight". It diffuses through the inner tube faster than air, apparently due to greater solubility in the rubber, so the tires lose pressure faster.

Uh, I thought the whole point was to prevent the tire pressure from changing substantially once it heats up, and that any other benefits are secondary.

Was the improvement 1 mile per gallon or 1 meter per gallon? The latter seems more likely to me.

I think the concept of using nitrogen isn't about choosing an ideal gas, but more about eliminating water vapor in the air.

Water condensing and evaporating doesn't expand/contract as predictably as any gas, and is the main cause of concern for racing tires where the temperatures are regularly over 100 degress C, (212F if you're a nascar fan).

Oxygen breaks stuff down quickly, and nitrogen is abundant and cheap. So use pure nitrogen not because it's pure, but because it's dry.

I'm probably totally wrong, so no need to bite my head off if I am, but that's my 2cents.

yeah, good point, I kind of heard the news report, heard it was about cars and didn't pay much more attention. There is a good chance I miss heard the mpg savings. Regardless of any energy savings you might get, I have to add air to my bicycle tires a little less than twice a week, for my car it's better, but still once per month. This means to keep them at proper inflation you would probably need your own nitrogen tank system.

So why do they use Nitrogen in Nascar?

You are not wrong about water and such as Nitrogen is an inert gas.

The bigger impact on bikes, as per a recent article I read would be that Nitrogen molecules are bigger than Air so you would lose less air and not have to fill your tires as often.

Also, the $2 - $5 per tire includes free refills.

Is it just a botique scam, probably. I'd certainly love to fill my tires less often, but not at $10 per bike.

People are starting to put nitrogen in their everyday car tires. One benefit is that tires lose less air, so less pumping.

That might make sense. Air is 70% nitrogen to start with. Helium is what you want for light + nonreactive. You'd have to fill your tubes up every 30 miles, probably.

LBS guy was talking about using latex tubes (more porous) and nitrogen (smaller molecule than, well, the other 30% of what's in air), so definite recipe for constant topping off of tires in exchange for supreme weight weeniness. But really, if N2, why not He?

Setting aside that N2 is already 70% of air, its molecules are actually smaller than what is most of the rest (O2 and CO2). Free refills are cool, though. As long as you don't have too many flats, I guess, to soil your tubes w/ plain old atmospheric stuff.

I was thinking of trying aerosolized testosterone in my tires.

as long as you use enough weaponized epitestosterone to keep the ratio below 4:1 you should be fine.

Natural gas is cheap and easily accessable through the valve behind your oven.

I prefer a 78% nitro, 21% oxygen blend, with just a hint of argon and a dash of CO2