I will add this Nitrogen does not expand and contract due to heat like air. Also it does not condensate.
WRONG! Nitrogen expands and contracts due to heat just like air. In fact, air is 78% nitrogen. The reason shocks are charged with nitrogen instead of plain ole air is A) there will be no moisture present, B) the nitrogen will have a more CONSISTENT expansion rate than a mixture of nitrogen, oxygen, argon, CO2, etc (air), and C) nitrogen is a noble gas and will not react with the rubber bladder causing deterioration of said bladder.
Recall your basic chemistry......P=nRT/V. Pressure is equal to a constant (n) times rate of expansion (R) times temperature (T) divided by volume (V). As you can see the pressure of ANY gas is directly related to the temperature of the gas. Change the temp and you change the pressure.