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MTB Suspension Sales, Service & Support

Nitrogen in your suspension

Posted on May 01 2016

At Cyclinic, we use Nitrogen instead of 'regular air' for inflation of suspension components to the customers desired specification or recommended pressure settings. Yep, even in the air can of your Fox or Rockshox rear shock, the air chamber of your Fox, Rockshox, Lefty or Headshok forks, and heck we'll even use it in your blow up pool toys if you really want. But the big question we often get asked is... Why?  

 

What makes nitrogen such a great inflation gas for suspension?

Well actually, nothing… or more precisely, the fact that it is nothing. Nitrogen is an "inert" gas, meaning it's a property-free, non-reactive substance or, more simply put: "nothing." And nothing is exactly what your forks or shocks should be filled with, as in: nothing but pressure.

 

So if nitrogen is nothing, how can it possibly have any benefit? 

Well the answer is that it has no benefit... until you compare it to the alternative, which is air. The good old regular air that we have been using to inflate our forks, shocks and tires is already 79.1% nitrogen. The problem with regular air and the reason it is such a poor inflation medium is that it also contains about 20% oxygen. 

As we all know, Oxygen is essential for human survival (and almost every other living organism for the record), however it can also be quite destructive to everything else around us. For example, think about the term "Oxidation". Oxidation, also known as rust or corrosion is the absolute enemy of anything composed of Alloy, Rubber or even steel - Such as your Shocks IFP chamber and Air Can, Your Fork's air cartridge, or even your mtb tires. Corrosion in suspension components is often caused by moisture content in area's where moisture should really not exist, thanks to Mr Oxygen.

 

Ok that's cool, but why use it in my fork or rear shock? 

Reason 1a:

Because we can :) Cyclinic is equipped to 'charge' any Fox, Rockshox or Cannondale suspension component with Nitrogen, and it's a standard part of every single service we do, without any additional cost to you - so why not? But here's the techy reasons why we use it:  

Reason 1b: 

Say no to corrosion! Because Nitrogen is an inert gas and is oxygen free, it is impossible for oxidation or corrosion to occur. Without the presence of oxygen (The 'O' in 'H2O'), water or condensation cannot form inside your forks or shock, hence a corrosion or oxidation free air chamber.

Reason 2: 

Live longer! Nitrogen give's your rubber o-rings and seals a greater chance at a long healthy life, with less contamination from water vapor's found in 'regular air'. Those water vapors actually act as a catalyst, accelerating rust, corrosion and oxidation of your shock's rubber compounds/seals. When your seals oxidize, or decompose, they loose the ability over time to do their job - Seal. As a result, broken down seals can affect the fork or shocks ability to hold pressure, remain clean and or contaminant free. Basically, Nitrogen gas is virtually water vapor free, and that's a good thing!

Reason 3: 

Keep your cool! Water vapor also absorbs and holds heat. When it changes from liquid to vapor, water also expands tremendously in volume. So, for example - When your shock is inflated with 'air', it will generate heat quicker than it would when compared to if it was inflated with Nitrogen - Because Nitrogen is dryer. Now picture the insides of your rear shock after 5 minutes of descending down your favorite trail, and think about the heat that is generated by the constant compression and rebound of the air  inside. A rear shock on our hand-dyno at Cyclinic can generate heat in just 10 quick cycles!

Reason 4: 

Pressure is on! Nitrogen has far better pressure retention. The most detrimental property of oxygen is actually its small molecular structure. A molecule of oxygen, which again comprises about 20% of regular air, is roughly 1/4 of the size of a molecule of nitrogen. Oxygen molecules are so small that it is completely normal for air filled forks or shocks to lose 3-5 PSI each month from "permeation." Permeation is the normal process by which the oxygen molecules in compressed air seep through a shock's air can, an air valve or fork's top cap. Nitrogen filled forks or shocks, on the other hand, typically lose no pressure from permeation… even over many months of use. So, by inflating your forks or shock with high purity nitrogen, they will remain at their set pressure much longer. 

Reason 5: 

Im on fire! Nitrogen is non-combustible, so when you're ripping the trails to pieces while chasing Strava KOM's, you wont suddenly find your fork or shock on fire due to the excessive heat build up. That's a fact!... But about as likely as a Zombie Apocalypse. :) 

 

FAQ:

What if I need to adjust the air pressure after you have serviced my fork or shock?  

There is no problem at all with using a standard shock pump to adjust the pressure up or down. The more regular air pressure you put in, just reduces the Nitrogen concentrate inside.

Is Nitrogen dangerous or explosive?  

No - Nothing to worry about here. It's just air without the Oxygen. Nitrogen is commonly also used for storing and packaging of snack foods, coffee, and other food items - So it's very safe. 

 

See the pics below that show how much 'air' is used inside your common suspension forks/shocks. (Shown in light blue)

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