Not going to delete to lose the down votes.
The stated question is advantage is nitrogen. Not should I use nitrogen.
I cover the technical side of the characteristics of nitrogen versus air and the chemical and physical reason for the differences.
- A nitrogen molecule is larger than oxygen so it does not leak as easily/rapidly.
Nitrogen is actually a little lighter than oxygen and an nitrogen atom is smaller.
In air they both occur as molecules of two atoms.
The they way the hold hands is different so N₂ is slightly bigger then O₂.
O2 "permeates" approximately 3-4 times faster than does N2 through a
- Stable and non-reactive.
Oxygen, nitrogen, are water are all relatively stable and non-reactive.
Oxygen is a stronger oxidizing agent.
Nitrogen oxidizes the rubber at a lower rate.
- Better PVT characteristics. Nitrogen does not change pressure with temperature as much as air. You don't want the pressure in your tires to change.
- Storage and transportation
There are some of rent a bike racks the use nitrogen because it is easier to get a storage and transportation permit. Oxygen alone is not combustible but it supports combustion. Nitrogen is not combustible does not support combustion.
Why nitrogen versus an inert gas such as Argon?
Nitrogen exists as a molecule N₂ and is nearly as stable as an inert gas. It is used because it is available. Nitrogen is a byproduct of liquefaction and fractional distillation of air to produce oxygen. Nitrogen is not an inert gas but a nitrogen molecule N₂ is very stable. It is a relatively cheap dry stable (non reactive) gas. And does not easily liquefy (boiling point of -320 F).
Why does Nitrogen have better PVT characteristics?
In the operating range of a tire oxygen and nitrogen have the same PVT characteristics.
They are both ideal gasses. Ideal in that they don't liquefy and have neither attractive nor repulsive forces. They are neutral.
A bicycle does not generate enough friction to change the temperature much. Bicycle will be pretty close to ambient temperature. If you start a ride in the AM you may get a 10 Celsius swing by 2 PM.
Relative to the ideal gas law, PV = NRT, oxygen and nitrogen have the same behavior. T is absolute in that equation. 0 Celsius is 272 Kelvin (absolute). 10 to 20 Celsius is a difference of 4% in pressure. So if the tire started at 100 PSI the pressure when to 104 PSI.
Water is the PVT problem. Water is not an ideal gas. In the operating range of a tire H₂0 can exist as a gas and a liquid. From the liquid state to gas state the volume change is over 100 (this is how you can inflate a tire with a little CO₂ cartridge).
In the range of 10 Celsius versus 20 Celsius the vapor pressure of H₂0 nearly doubles at atmospheric pressure.
Vapour pressure of water
Over that same 10 Celsius swing what is the pressure change of water. The vapor pressure of water doubles. Where the ideal gas (N₂) changes 4% water changes 100%. In that same range the water pressure goes up 1 PSI. So the total PSI is 105. At only 1% composition water contribute 25% of the pressure change. The statement from Moz that Nitrogen changes pressure with temperature slightly less than water does is not correct. The difference is 40X but at only 1% that 40X is still not much of a total contribution.
So a 1% pressure difference in 10 centigrade. Racers will go after grams. 1% may matter to them. It is not clear if racers users nitrogen (in tires). I see sellers stating it is used by races but I don't see and races saying they use nitrogen.
Nitrogen is used in altitude tents to reduce the O₂ content. This stimulates the production of red blood cells. So racers may use tires as an excuse for nitrogen tanks.
From 0 to 100 Celsius the vapor pressure of H₂0 goes from 611 to 101417 Pa. In that operating range H₂0 is over 100 times more sensitive to temperature than nitrogen or oxygen relative to pressure. So for a race car the change is noticeable.
Why CO₂ in those portable canisters and not nitrogen?
CO₂ compresses to liquid state at a lower temperature then nitrogen. The boiling point of CO₂ is -78 Celsius. Can use CO₂ to inflate a tire and not risk it going back to a liquid state in the operating range of a tire.