Nitrogen filled tyres?

nerak

I've just been thinking can this be done and would it be of benefit (to pro's not moi!)

Oxygen atomic weight 15.9994g

Nitrogen atomic weight 14.0067g

supersonic

You replace 20% of the air with more N2. Talking about a 1g saving with a standard 30psi (or there abouts!)

ThanksBye

But one mole of gas takes up around 23L so even at pressure the savings woiuld be tiny

The Northern Monkey

fill them with hydrogen

ratty2k

Only reason it used in some cars is the fact it doesn't expand as much.

supersonic

ratty2k wrote:

Only reason it used in some cars is the fact it doesn't expand as much.

Only if the nitrogen is free from water vapour - ideal gasses all expand the same.

fenboy369

Dry Nitrogen is used in aircraft tyres as it has no water in it and doesnt corrode the wheel assembly. Also less volitile if a brake unit over heats and causes the wheel to go bang.
I have filled my tyres with it, and it didnt seem to make any difference in MTB or road tyres. But then I do have fat arse.... :oops:

ride_whenever

there are no ideal gases, particularly diatomics.

The noble gases play closely though.

supersonic

ride_whenever wrote:

there are no ideal gases, particularly diatomics.

The noble gases play closely though.

Close enough here though for the approximation to work ;-)

ride_whenever

depends on the accuracy you want :P

supersonic

Hehe, you chemist you!

turnerjohn

I have heard that nitrogen leeks out of the tyres quickly...so its an expensive excersise !

supersonic

It shouldn't do - air is nearly 80% nitrogen!

The Northern Monkey

what about helium?

supersonic

I can do the calculation, but the bike will weigh about 7g less IIRC.

The Northern Monkey

so why not helium then?! have fun filling up and a lighter bike!!

Argon? thats a gas isn't it? what about that?

Also, my farts are pretty light.... they always "drift" upwards...

ratty2k

Helium would leak through the walls of the innertubes. We used it for leak chasing high vacuum components due to its ability to get through tiny tiny gaps that air wouldn't.

GHill

bigbenj_08 wrote:

so why not helium then?! have fun filling up and a lighter bike!!

It's expensive (relative to nitrogen/air), more difficult to handle and will escape at a faster rate than air.

Argon? thats a gas isn't it? what about that?

It's heavier than nitrogen and oxygen.

xtreem

[b]fenboy369[/b] wrote:

Dry Nitrogen is used in aircraft tyres as it has no water in it and doesnt corrode the wheel assembly. Also less volitile if a brake unit over heats and causes the wheel to go bang.

I don't think it's the corrosion that they are worried about.
It's the fact that when landing the plane the wheels accelerate from 0 to 300km/h in a
split second. That heats up the tire to those temperatures that if it was any water inside it,
the tire would explode. (the water explodes, and bang, there goes the tire)

fenboy369

Ever put your hand on a tyre just after landing? They dont get all that hot mate. There is no way that its hot enough to auto-ignite water. Corrosion effects, water freezing in the tyre assembly at altitude, less pressure loss than straight air, more stable gas expansion when heated. Thats why we pump a/c tyres with dry nitrogen.

RichMTB

The difference would be so small as to be entirely negligible, for any improvement in weight that can be measured in single digit grams any improvement is almost always psycological

Personally I fill my tyres with virgin faeries farts

robertpb

The air in my Conti tubes commutes too much for me to go around spending money on filling them up again with anything but free air.