Mountain Bike Reviews Forum banner

21 - 40 of 73 Posts

·
Glad to Be Alive
Joined
·
42,968 Posts
ridefreeride said:
Isn't there already nitrogen in some rear shocks?

Seems to me that my fox van r has nitrogen in it.
Just curious

yes fox does a lot of their coils with nitrogen
 

·
Glad to Be Alive
Joined
·
42,968 Posts
Bikesair said:
I'm sure that's an advantage SMT but it's not the primary reason people use nitrogen in their tires. Highdelll hit the nail on the head. Really, the only reason nitrogen is even used over other gases is because it's the easiest to isolate. CO2 is cheaper but it has other downfalls.
for everyday passenger cars that is the primary reason....for people who don't check air pressure in tires as much....just less maintenance
 

·
Registered
Joined
·
9,873 Posts
the only difference is that nitrogen is clean and dry. compressed atmospheric air, even in the driest places, has water in it. especially in a air shock that gets heated up, water is going to make an impact on performance.

if you had a compressor setup with driers, pure nitrogen would be useless. since most people dont, nitrogen fills sort of make sense.
 

·
Registered
Joined
·
276 Posts
SHIVER ME TIMBERS said:
contrary...the reason they use nitrogen in car tires is it seeps out slower because they are thicker molecues....therefore tire stay at same pressure longer then just air...
I don't know what you mean by "thicker", but the three main components of air are Oxygen, Nitrogen, and Carbon Dioxide. N2 is the smallest of the three diatoms, as well as the least dense at 0* C.

You can't really argue against physical properties. If you concentrate a gas inside something higher than in naturally occurs in our atmosphere, the gas will follow its concentration gradient until it reaches an equilibrium. This is why a balloon filled with helium that floats, after a few days no longer floats. The balloon leeches helium into the air surrounding it. Also, because of the root mean square velocity equation, nitrogen having a small molecular mass, will have a very fast velocity, meaning it will diffuse faster than the other gas molecules that naturally occur in air.
 

·
I can ride a two-wheeler
Joined
·
647 Posts
Discussion Starter #25
Has anyone filled their shock with nitrogen? How much would it cost and where can I get some?

...if it's cheap, I may as well give it a shot
 

·
Stay thirsty my friends
Joined
·
885 Posts
Race cars use nitrogen in their tires to prevent moisture from entering the tire, race car tires temps easily exceed the boiling point of water at which point that moisture turns to steam causing tire pressures to increase dangerously. Tire temps commonly hover around 200F-250F once hot on the race track.

Dried air will achieve the same function but nitrogen is commercially bottled in high pressure cylinders making them easy to procure and a small bottle can fill a lot of tires making them convenient to use and store. The other stated reasons to use nitrogen are miniscule in practice and rarely assist a tire in retaining its pressure or aid in its cooling although it is measurable (if only slightly) so not entirely untrue.

NASCAR Information

Fundamentally; air, oxygen and nitrogen will all behave exactly the same in terms of pressure change for each 10 degrees of temperature change. However temperature alone is not the whole story.

Ambient air contains moisture, nitrogen does not. If moisture is present it contributes to a greater change in pressure simply because at lower temperatures water condenses to become a liquid. The liquid form of water occupies very little volume and contributes only a negligible pressure to the tire. But at higher temperatures, such as those in a running tire, water evaporates inside the tire and becomes a gas which increases pressure in the tire.

Ambient air contains about 21% oxygen. Oxygen’s smaller molecular size allows it to permeate through the rubber of the tire. By inflating with nitrogen, which is much less permeable than oxygen, the pressure changes due to oxygen loss are greatly reduced.

The racing industry is correct; nitrogen is more predictable. Because nitrogen is dry it has no moisture to contribute extra pressure changes with temperature. Because nitrogen permeates out much slower than oxygen pressure changes due to that leakage are almost eliminated compared with ambient air.
http://www.getnitrogen.org/sub.php?view=nascar
 

·
Go back to school
Joined
·
648 Posts
Diggidy said:
I don't know what you mean by "thicker", but the three main components of air are Oxygen, Nitrogen, and Carbon Dioxide. N2 is the smallest of the three diatoms, as well as the least dense at 0* C.
.
Um where did you read that N2 is the smallest. I know that nitrogen is a bigger atom than oxygen so I would be inclined to believe that the diatom of each would fallow the same principle...
 

·
moaaar shimz
Joined
·
9,125 Posts
Soooooo much ignorance. I don't think we need more answers as several bright dudes in the forum have answered correctly, but just to make sure:

Pressurized nitrogen is used because it's almost inert and lacks moisture, two properties you definitely want in an application in which you need constant/predictable pressure and corrosion resistance; shocks.
 

·
Registered
Joined
·
276 Posts
Bikesair said:
Um where did you read that N2 is the smallest. I know that nitrogen is a bigger atom than oxygen so I would be inclined to believe that the diatom of each would fallow the same principle...
Yeah, I don't know why I said that. Got my periodic trends reversed. Still, as far as atomic radii is concerned, nitrogen is a very small molecule, and smaller than the carbon atoms that compose the majority of rubber's chemical makeup.
 

·
Glad to Be Alive
Joined
·
42,968 Posts
4JawChuck said:
Race cars use nitrogen in their tires to prevent moisture from entering the tire, race car tires temps easily exceed the boiling point of water at which point that moisture turns to steam causing tire pressures to increase dangerously. Tire temps commonly hover around 200F-250F once hot on the race track.

Dried air will achieve the same function but nitrogen is commercially bottled in high pressure cylinders making them easy to procure and a small bottle can fill a lot of tires making them convenient to use and store. The other stated reasons to use nitrogen are miniscule in practice and rarely assist a tire in retaining its pressure or aid in its cooling although it is measurable (if only slightly) so not entirely untrue.

NASCAR Information

Fundamentally; air, oxygen and nitrogen will all behave exactly the same in terms of pressure change for each 10 degrees of temperature change. However temperature alone is not the whole story.

Ambient air contains moisture, nitrogen does not. If moisture is present it contributes to a greater change in pressure simply because at lower temperatures water condenses to become a liquid. The liquid form of water occupies very little volume and contributes only a negligible pressure to the tire. But at higher temperatures, such as those in a running tire, water evaporates inside the tire and becomes a gas which increases pressure in the tire.

Ambient air contains about 21% oxygen. Oxygen’s smaller molecular size allows it to permeate through the rubber of the tire. By inflating with nitrogen, which is much less permeable than oxygen, the pressure changes due to oxygen loss are greatly reduced.

The racing industry is correct; nitrogen is more predictable. Because nitrogen is dry it has no moisture to contribute extra pressure changes with temperature. Because nitrogen permeates out much slower than oxygen pressure changes due to that leakage are almost eliminated compared with ambient air.



http://www.getnitrogen.org/sub.php?view=nascar
there it is right there....Nitrogen molecules are bigger
 

·
Glad to Be Alive
Joined
·
42,968 Posts
Diggidy said:
I don't know what you mean by "thicker", but the three main components of air are Oxygen, Nitrogen, and Carbon Dioxide. N2 is the smallest of the three diatoms, as well as the least dense at 0* C.

You can't really argue against physical properties. If you concentrate a gas inside something higher than in naturally occurs in our atmosphere, the gas will follow its concentration gradient until it reaches an equilibrium. This is why a balloon filled with helium that floats, after a few days no longer floats. The balloon leeches helium into the air surrounding it. Also, because of the root mean square velocity equation, nitrogen having a small molecular mass, will have a very fast velocity, meaning it will diffuse faster than the other gas molecules that naturally occur in air.
wrong.....Nitrogen is a bigger molecule then oxygen
 

·
Now with More Wood
Joined
·
2,964 Posts
I knew I would not be disappointed with this thread when I saw "Nitrogen" in the title, and 35 posts already...

:D

The real question is how many people would actually notice a difference in bike/suspension behavior during their runs due to use of air instead of pure nitrogen in their shocks ?
 

·
Braaaapp!
Joined
·
477 Posts
Iceman2058 said:
The real question is how many people would actually notice a difference in bike/suspension behavior during their runs due to use of air instead of pure nitrogen in their shocks ?
Probably no one, if you didn't tell them.

I've read that many suspension tuners in the moto world will use air when making many changes on a shock during a day or testing weekend. They just fill ~5 psi less than they would with nitrogen to compensate for the expansion from moisture. Once everything is sorted out and final valving is picked most will fill with nitrogen.

How hot do MTB shocks get? I've gotten my motorcycle shock hot enough that you can't touch it plenty of times. I've read that 200+ degrees is common, and one tuner mentioned a pro topping 275F on a hot summer day in the whoops. Just the unsprung weight in the rear of a motorcycle is probably equal to or greater than the weight of some complete bicycles. Takes a lot of damping to deal with those forces.
 

·
Registered
Joined
·
276 Posts
SHIVER ME TIMBERS said:
wrong.....Nitrogen is a bigger molecule then oxygen
First, we already got that out of the way a few posts up. Phenomenal reading comprehension.

I still don't quite get what you think that proves though? Other people, including myself, have said the real reason N2 is used is because it's anhydrous, and so it has more consistent thermal expansion.

You seem to have a pretty tenuous grasp on what we're talking about, so I'm just going to stop.
 

·
Registered
Joined
·
113 Posts
adam728 said:
Probably no one, if you didn't tell them.

I've read that many suspension tuners in the moto world will use air when making many changes on a shock during a day or testing weekend. They just fill ~5 psi less than they would with nitrogen to compensate for the expansion from moisture. Once everything is sorted out and final valving is picked most will fill with nitrogen.

How hot do MTB shocks get? I've gotten my motorcycle shock hot enough that you can't touch it plenty of times. I've read that 200+ degrees is common, and one tuner mentioned a pro topping 275F on a hot summer day in the whoops. Just the unsprung weight in the rear of a motorcycle is probably equal to or greater than the weight of some complete bicycles. Takes a lot of damping to deal with those forces.
Nitrogen is cheap. I worked as a mechanic at a yamaha shop for years, I would just take are whole bottle to the track.

Fox builds air shocks for quads and pitbikes. I noticed on long motos some change in low speed compression and rebound but it wasn't that bad. I had a float on my KLX110 and tried using nitrogen a few times instead of air. It wasn't enough of a differnece for me to bother doing.


I am supprised that people are not more concerened about running a lighter weight oil then running nitrogen. Modern MX suspension uses 0 Wt so the viscosity does not change with heat. It would be a much more notcieble difference in getting consistent dampening to set up this way.
 

·
Braaaapp!
Joined
·
477 Posts
181picklz said:
Nitrogen is cheap. I worked as a mechanic at a yamaha shop for years, I would just take are whole bottle to the track.

Fox builds air shocks for quads and pitbikes. I noticed on long motos some change in low speed compression and rebound but it wasn't that bad. I had a float on my KLX110 and tried using nitrogen a few times instead of air. It wasn't enough of a differnece for me to bother doing.


I am supprised that people are not more concerened about running a lighter weight oil then running nitrogen. Modern MX suspension uses 0 Wt so the viscosity does not change with heat. It would be a much more notcieble difference in getting consistent dampening to set up this way.
Nitrogen may be cheap, but zero-loss chucks and the regulators cost a bit more than your average DIY guy will probably want to spend.

Oil weight has little to do with viscosity change due to temperature. Viscosity Index shows how a oil reacts as temp changes. A 15W oil may be more stable than a 0W, or vice versa.
A great link for suspension fluids, put together by PVD, a regular here.
https://www.pvdwiki.com/index.php?title=Suspension_Fluid

 
21 - 40 of 73 Posts
Top