Different Gasses in air sprung suspension?

[Hamo]

Ok.. i did search and didn't find anything..

but I was thinking today... if you could change the type of gas (air)in an air sprung fork/shock... would it make any/ much difference to the performance of the shock... Ie.. Helium instead of the regular mix of gasses in the regular air).. or would the purity of the air (as in just one element or compound rather than a mix) make any difference... Ie..(not too good on chemistry) but if different gasses compress easier/ harder than others then maybe the compression would be inconsistant with mixed air?.. maybe not..?
meh.. I was just musing but thought I'd put it up here to see if it would actually make any difference or not..
(and for the weight weenies.. Helium in your forks.. woo)..

might be an experiment for someone who could work out a way how to get some helium or something into their forks?

 

[WolfCreekPsycho]

If you were to do this...you'd probably want to go for Nitrogen. It stays constant regardless of altitude or temperature... so when you set your fork pressure on a cold winters day at sea level it will be the same when you take your bike to Thredbo on a hot summers day.

The reality in doing something like this is you are screwed if you want to change your pressures depending on the terrain and riding conditions.

 

[alchemist]

might be an experiment for someone who could work out a way how to get some helium or something into their forks?

Getting it in is easy, getting it to stay there is another matter.

 

[alchemist]

If you were to do this...you'd probably want to go for Nitrogen. It stays constant regardless of altitude or temperature... so when you set your fork pressure on a cold winters day at sea level it will be the same when you take your bike to Thredbo on a hot summers day.

Wwwwahhh?!?!?! The pressure in your forks is near enough directly proportional to the temperature (in Kelvin) regardless of what gas you use.

 

[Customjimmy]

White Brothers used Nitrogen in some of their forks. The Atmosphere is about 80% Nitrogen anyway so it's a bit of a wank. I guess you could use cartridges like the CO2 inflators do to keep it topped up but there's still the main problem of expense. Gases with different expansion rates to air might play havoc with air seals and fork tuning too if you go through large changes in temperature.

 

[WolfCreekPsycho]

Wwwwahhh?!?!?! The pressure in your forks is near enough directly proportional to the temperature (in Kelvin) regardless of what gas you use.

oops my bad... was losely based on Nitrogen running at a cooler temp than air.
"Nitrogen is claimed to provide a more stable pressure range in relation to tyre temperature"

 

[Andy.G]

Wwwwahhh?!?!?! The pressure in your forks is near enough directly proportional to the temperature (in Kelvin) regardless of what gas you use.

Hmmm ... yes, true - but then there is the consideration of Avocado's Law in relation to density ... (actually Avogadro's ... just can't get that out of my head from tech though ). Ignore me here - just being a dilettante !!! You are correct alchemist.

Nitrogen is used in tyres and landing gear struts in aircraft due to it being inert. Will not aid combustion. Will not oxidize. Larger molecule size will aid in pressure retention through porous materials - i.e tyre walls.

Just do NOT use pure oxygen ... that will end in tears.

 

[tu plang]

Just do NOT use pure oxygen ... that will end in tears.

yeah, hydrogen is where the real money is at.

 

[toodles]

Only reason nitrogen is used for stability is because it's cheap and dry. The lack of humidity reduces the coefficient of expansion and gives less extreme variances in pressure due to temperature change.

 

[kidafa]

the majority of moto shocks are nitrogen charged.... If you really want take ur shock/shocks to ur local moto shop and ask them to fill it to ur recommended psi with nitrogen if you really want to try it. Nitrogen is more consistent and wont heat up as much over long runs.... maybe keeping dampening oil cooler?? :S?

 

[Daver]

I hear that when you run air forks running on helium they blow up an octave higher.

 

[Hamo]

hmm... interesting..I'm not thinking of doing it.. I was just wondering if it would make the suspension feel notably different...

 

[Jon]

if it would make the suspension feel notably different...

You might be able to pick the difference in lab testing but on a trail there are to many other variables to be able to isolate any change imo.
cheers jon

 

[treggs]

Nitrogen is used in tyres and landing gear struts in aircraft due to it being inert. Will not aid combustion. Will not oxidize. Larger molecule size will aid in pressure retention through porous materials - i.e tyre walls.

True, although pressures used in aircraft struts and tyres are considerably higher.

Just do NOT use pure oxygen ... that will end in tears.

Oxygen will cause hydrocarbons to explode and will massively increase combustion rates in things like magnesium and aluminum. So if you inflate your sticky rubber DH tyres with it, they may spontaneously ignite mid run, allowing the oxygen to escape and assist with the rapid combustion of your frame and forks. This will cause you to fall face first into the rock garden, as you slap your own nuts trying to put out the flames of your nylon DH shorts.

 

[slip]

If anyone does want nitrogen in their forks or tyres many car tyre shops have nitrogen, used to have my car tyres filled with it.

 

[Binaural]

Only reason nitrogen is used for stability is because it's cheap and dry. The lack of humidity reduces the coefficient of expansion and gives less extreme variances in pressure due to temperature change.

Spot on. If you wanted even better temperature stability you'd go for carbon dioxide, but it's fairly toxic. I know some types of food packaged with inert gas use CO2 in preference to N2 when they have to be freighted by air.

 

[NCR600]

Spot on. If you wanted even better temperature stability you'd go for carbon dioxide, but it's fairly toxic. I know some types of food packaged with inert gas use CO2 in preference to N2 when they have to be freighted by air.

I'd have thought that processed meats were packaged with Sulfur Dioxide, that's what it smells like any way!

Just to reiterate what everyone has said, so it doesn't look too much like I'm being a smart arse:

Nitrogen gets used to pressurise shock absorber remote reservoirs and in race car/bike tyres due to it's temperature stability.

There is no reason why you couldn't use it in SPV chambers, air preload chambers and the like, and there would be some advantage (although maybe not that the average rider could tell) from it's use. The problem I can see would be metering the small volume/relatively high pressure required without spending bulk $$ on the equipment to do so. The cost would likely outweigh the advantage.

Oh yeah, Honda used helium in the tyres of their ultra tricky 500 and 350 cc 6 cylinder bikes in the mid 60's. But then again, that's Honda for ya!