Nitrogen in shock?

[purple gerbil]

Talking of shocks in a recent post had me thinking. A few months ago on Top gear they was talking about nitrogen in tires,could this be used in air shocks? Would there be any benefits?or just an unnecessary cost?

Quite possibly a stupid post 

[beeeerock]

Nitrogen is becoming more common in car tires these days.  My understanding is that it doesn't see as much variation in pressure due to temperature and that it doesn't migrate through the containing materials as quickly.

I haven't looked at the thermodynamic properties to confirm the pressure/temperature idea and the lower number on the periodic table makes me suspicious of the migration thought... but they make a good story and there must be a good reason for use in tires.  A Google investigation for me some evening... 

It would also be more complicated to prepare nitrogen for use, so water vapour would likely be removed, meaning corrosion would be reduced.

Putting all these ideas together I'd think that Nitrogen could be used in air shocks.  Given the potential for heat buildup in a shock (probably more significant than a car tire), this might result in a more consistent 'ride'.

It makes me wonder how the 'gas-adjust' shocks I recall being sold for cars actually worked.  I think KYB and Bilstein made them, might still do... been out of that teenager car obsession since... well, since I was a teenager... 

[Colin]

Absolurtely! Nitrogen IS used in our "air"/oil Noleen shocks for the reason of increased stability of pressure at various  temperatures. An incidental benefit is the lack of water vapour, but dry air would fulfil that, but I think Nitrogen won't froth with oil as much as air would.

Where our shocks are "fill once" that is practical, but with variable adjust pure air shocks, these second class citizens <GRIN> have to make do with merely 78% Nitrogen. Aren't we lucky!

Col.

[beeeerock]

 

Now I'm wondering about those 'gas-adjust' shocks I had on the old 145 Volvo... They stiffened up quite nicely when you drove it hard or over rougher roads, then would soften for highway driving.  All by themselves.  I wonder if a bike shock every incorporated that technology?  Having been out of the cycling loop for so long, I have no idea...

[fyrstormer]

Absolurtely! Nitrogen IS used in our "air"/oil Noleen shocks for the reason of increased stability of pressure at various  temperatures. An incidental benefit is the lack of water vapour, but dry air would fulfil that, but I think Nitrogen won't froth with oil as much as air would.

Nitrogen is used in oil-dampened coil-sprung shocks not because of thermal stability, but because it doesn't react with anything (nitrogen really just wants to be bonded to itself), because it's plentiful and cheap to distill (air is 78% nitrogen), and because once it's been distilled there is absolutely no water in it to cause corrosion. The nitrogen is used to pressurize a secondary floating piston on top of the damping oil, to take up the extra space above the oil without allowing the oil to froth and change viscosity. Air would serve the same purpose, but the oxygen and humidity would eventually corrode the floating piston.

For *air*-sprung shocks, nitrogen would probably produce a slightly more consistent spring rate across a wide range of temperatures, and again the lack of oxygen and humidity would help prevent corrosion. I don't know if the slightly more consistent spring rate would significantly improve shock feel, though.

I use nitrogen in my car tires, but only because my car came with tire-pressure sensors, and they need to be protected from humid air so they won't corrode or short-circuit on cold days.

[purple gerbil]

For air sprung shocks, nitrogen would probably produce a slightly more consistent spring rate across a wide range of temperatures, and again the lack of oxygen and humidity would help prevent corrosion. I don't know if the slightly more consistent spring rate would significantly improve shock feel.


This is what I was kinda asking,fyrstormer hit the nail on the head I was thinking more along the lines of the temperature stability.

[fyrstormer]

You can always try it and find out if it makes a difference, but keep in mind you'll have to use a source of pure nitrogen every time you want to top-off the pressure in the shock in order to maintain the "advantage".