Anyone use nitrogen in their air shock?- Mtbr.com
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  1. #1
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    Anyone use nitrogen in their air shock?

    Anyone have any experience using nitrogen instead of air in your shock? Theoretically, nitrogen would leak less readily because it is a larger molecule. Anyone tried it? Also, it should be less sensitive to temperature change since it is drier than air. The temp change issue has been discussed before and the conclusion was that the actual difference isn't enough make a practical difference.

    Anyone tried it?
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  2. #2
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    yes, i do it all the time. makes the fork heavier tho.

    http://www.mistupid.com/chemistry/aircomp.htm

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    Sheesh. Cut a guy some slack.

    Quote Originally Posted by drunkle
    yes, i do it all the time. makes the fork heavier tho.

    http://www.mistupid.com/chemistry/aircomp.htm
    Okay, okay, I guess I had that coming. I meant PURE nitrogen.
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  4. #4
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    Potential problem.

    Quote Originally Posted by Appendage
    Anyone have any experience using nitrogen instead of air in your shock? Theoretically, nitrogen would leak less readily because it is a larger molecule. Anyone tried it? Also, it should be less sensitive to temperature change since it is drier than air. The temp change issue has been discussed before and the conclusion was that the actual difference isn't enough make a practical difference.

    Anyone tried it?
    Having serviced motorcycle shocks in years past, I'm wondering how you'll easily insure the right pressure each time you need to check and/or add nitrogen. We had a high pressure nitrogen bottle at the shop, and after a rebuild you'd have to feed the nitrogen into the serviced shock very carefully with a manual safety valve and guage to attain the right pressure. It was a small PITA when servicing a moto shock, but you only had to do this at rebuild time. I'd think it would be a royal PITA every time you needed to check and/or add nitrogen. And you know someone would screw up and let the full pressure of a topped off nitrogen service bottle go right into shock, which depending the shock might be rather fun. Nitrogen is nice in sealed environments that you don't have to constantly check, but I doubt it's worth it in the bicycle end of the suspension business where we're currently using air.

  5. #5
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    You'd need a second stage regulator

    Quote Originally Posted by TNC
    Having serviced motorcycle shocks in years past, I'm wondering how you'll easily insure the right pressure each time you need to check and/or add nitrogen. We had a high pressure nitrogen bottle at the shop, and after a rebuild you'd have to feed the nitrogen into the serviced shock very carefully with a manual safety valve and guage to attain the right pressure. It was a small PITA when servicing a moto shock, but you only had to do this at rebuild time. I'd think it would be a royal PITA every time you needed to check and/or add nitrogen. And you know someone would screw up and let the full pressure of a topped off nitrogen service bottle go right into shock, which depending the shock might be rather fun. Nitrogen is nice in sealed environments that you don't have to constantly check, but I doubt it's worth it in the bicycle end of the suspension business where we're currently using air.
    You'd need an adjustable second stage regulator to keep from sending full cylinder pressure into the shock. Set it at zero and slowly crack the valve until you reach the pressure you want. I'm not saying it's worth the trouble or expense, I was just wondering if anyone was doing it.
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    PUSH Does

    Every Air shock that we service goes out with Nitrogen in the Air spring. Not for performance reasons, but for convenience. We use special regulators and filling units for both the gas charge in the IFP chamber and air spring on air sprung shocks.

    At our level, having technicians pumping up shocks all day that they service with a trusty Fox Shox Pump isn't the way to go. Talk about arm pump!

    Darren

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    I guess...

    Quote Originally Posted by PUSHIND
    Every Air shock that we service goes out with Nitrogen in the Air spring. Not for performance reasons, but for convenience. We use special regulators and filling units for both the gas charge in the IFP chamber and air spring on air sprung shocks.

    At our level, having technicians pumping up shocks all day that they service with a trusty Fox Shox Pump isn't the way to go. Talk about arm pump!

    Darren
    It's convenient since many of the shocks you work on get a nitrogen charge?...like a Fox RC? You don't use a hand pump? What are you guys...wimps?...LOL! Your personnel in charge of pumping would wind up looking like Popeye!

  8. #8
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    you could do just as well with standard air compressor with a blow off valve.

    or... take a couple cans of whipped cream, inflate a balloon... shffffft!

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    For years I have only cuz we have a nitrogen setup used for our motocross applications.

  10. #10
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    Its actually quite simple... A/C dudes use nitrogen to pressure test refrigeration and heating units for leaks before they pump any expensive cooling gases into the system. The regulators are pretty simple and usually output something like 100 to 300psi.
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    What about helium?

    What about using helium in air shock?

    When I put helium in balloons they float, would using helium in an air shock make it lighter?

    I thought of it first before anyone goes off patenting anything!
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  12. #12
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    Quote Originally Posted by MagnumPI
    What about using helium in air shock?

    make it lighter?

    I thought of it first before anyone goes off patenting anything!
    Ummmm....no, you didn't....the idea of using helium to make mtbs "lighter" predates air suspension, I believe (folks used to wonder about having helium filled sealed frame tubes backin the day of rigid bikes, even.....) ....there ain't nothing truly new under the sun, anymore...

  13. #13
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    Nitrogen

    We use nitrogen in the Fox off-road shocks on our race buggy, and I tried to put it in my RP3 but the chuck would not fit so I just use air. The advantages of nitrogen are it's drier, so no moisture accumluates in the shock, and its properties change less with temperature, so it maintains a more consistent spring rate. This is important for off-road racing as the shocks are steel and can rust on the inside, and they also get quite warm over extended periods of time in really rough terrain. However, I don't think this would be noticeable on a bike shock as mine rarely gets warm and dryness is not a concern for corrosion in an aluminum shock. As far as the less leakage due to larger molecules, I think that is BS because air is mostly nitrogen, therefore how can nitrogen by itself have larger molecules than air which is nitrogen combined with other stuff?

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    4 of out 5 dentists choose nitrogen

    Quote Originally Posted by JustMtnB44
    We use nitrogen in the Fox off-road shocks on our race buggy, and I tried to put it in my RP3 but the chuck would not fit so I just use air. The advantages of nitrogen are it's drier, so no moisture accumluates in the shock, and its properties change less with temperature, so it maintains a more consistent spring rate. This is important for off-road racing as the shocks are steel and can rust on the inside, and they also get quite warm over extended periods of time in really rough terrain. However, I don't think this would be noticeable on a bike shock as mine rarely gets warm and dryness is not a concern for corrosion in an aluminum shock. As far as the less leakage due to larger molecules, I think that is BS because air is mostly nitrogen, therefore how can nitrogen by itself have larger molecules than air which is nitrogen combined with other stuff?
    Did you know that 4 of out 5 dentists choose nitrogen for their patients who chew shocks? Whether or not the big molecule thing is BS I can't say, but if so, it's not for the reason you stated. Nitrogen comprises a little under 80% of air. So, lets say the other 20% of stuff can leak out easier. A small percentage loss of volume of a compressed gas would make a significant difference in pressure, especially in a bike shock, where you're talking about such a small volume to begin with.
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  15. #15
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    oddly enough, high compression air tanks have been in use for far longer than mtb shocks. they dont have a problem with leakage unless an o ring cracks. for which case, the atomic size difference in molecules wont mean squat.

  16. #16
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    Quote Originally Posted by Appendage
    Did you know that 4 of out 5 dentists choose nitrogen for their patients who chew shocks? Whether or not the big molecule thing is BS I can't say, but if so, it's not for the reason you stated. Nitrogen comprises a little under 80% of air. So, lets say the other 20% of stuff can leak out easier. A small percentage loss of volume of a compressed gas would make a significant difference in pressure, especially in a bike shock, where you're talking about such a small volume to begin with.
    N2 and O2 are the main components of air... O2 molecule is bigger actually than N2... so all that argument is pure BS....


    Nitro is drier, more stable thru a range of temps, and the bottling process and stuff makes it to carry less dirt than air. Some air compressors use oil for lubrication and if you don't have an oil filter you can put a lot of gunk into your shock.

    N2 is better for IFP chambers that are not refilled often... other than that, air is fine.

    All you need to pump N2 is the bottle and a two stage regulator as said before. Just regulate the pressure you want and open the valve of the second reg until you have a low-steady flow. Regulators are available at welding supplies stores or HVAC supplies stores.

    The bottles you can get them from Medical, Welding or HVAC Gas suppliers. You can actually buy the bottle, have it on consignment or just pay for the gas if the company lets you keep the bottle. Bottles typically are pressurized to 2000-3000 psi. I really forgot the volume of gas and it really doesn't matter as there are several bottle sizes. Get the industrial grade N2. The Medical one is more pure and the high-purity is the more expensive but not worthy for a shock, IMHO.

    I've used it for pressure testing some tubing and piping systems. N2 is relatively cheap also and in some industries is a reject (oil industry comes to my mind).

    N2 desirable ?? Foock yeah!
    Strictly necessary? Not exactly. Depends on where in the shock.

    PS... this meter is for the stuff of Nitro leaking less than air.... not true.
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  17. #17
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    Quote Originally Posted by Warp2003
    N2 and O2 are the main components of air... O2 molecule is bigger actually than N2... so all that argument is pure BS....


    Nitro is drier, more stable thru a range of temps, and the bottling process and stuff makes it to carry less dirt than air. Some air compressors use oil for lubrication and if you don't have an oil filter you can put a lot of gunk into your shock.

    N2 is better for IFP chambers that are not refilled often... other than that, air is fine.

    All you need to pump N2 is the bottle and a two stage regulator as said before. Just regulate the pressure you want and open the valve of the second reg until you have a low-steady flow.

    I've used it for pressure testing some tubing and piping systems. N2 is relatively cheap also and in some industries is a reject (oil industry comes to my mind).

    N2 desirable ?? Foock yeah!
    Strictly necessary? Not exactly. Depends on where in the shock.
    Well, I guess you set me straight! What a guy!

    I got this off the Ingersoll-Rand website:

    Oxygen in compressed air can permeate the tire wall reducing tire pressure. With nitrogen, diffusion is 30 to 40 percent slower than oxygen. As a result, nitrogen maintains tire pressure longer than ambient air.

    The key phrase being "permeate the tire wall". I'll leave it to your BS meter to tell us whether or not nitrogen would be be less apt to sneak past seals and O-rings. Some shocks, even in good condition, are prone to leaking and I was wondering if N2 might be a work-around for those thus afflicted.
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  18. #18
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    Quote Originally Posted by Appendage
    Well, I guess you set me straight! What a guy!

    I got this off the Ingersoll-Rand website:

    Oxygen in compressed air can permeate the tire wall reducing tire pressure. With nitrogen, diffusion is 30 to 40 percent slower than oxygen. As a result, nitrogen maintains tire pressure longer than ambient air.

    The key phrase being "permeate the tire wall". I'll leave it to your BS meter to tell us whether or not nitrogen would be be less apt to sneak past seals and O-rings. Some shocks, even in good condition, are prone to leaking and I was wondering if N2 might be a work-around for those thus afflicted.
    I stand corrected. Give me that BS meter back!!.... My apologies.

    I'm wondering also if seals (viton, buna, PTFE??) have a higher/lower permeability than tires. PTFE for sure is less permeable.

    I think that pressure losses in shocks are for a very different reasons than permeability of sidewall in tires. To begin with, as you know, the shock sleeve (air chamber) slides over the shaft.. that alone can produce more losses than permebility of the seals. Some shocks lose their pressure also while just not working... so the permeability stuff holds water but I think losses are more for the construction of the shock than for permeability.

    I doubt N2 would help much with that. In that case, refilling will be a tad more complicated.
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  19. #19
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    Quote Originally Posted by Warp2003
    I stand corrected. Give me that BS meter back!!.... My apologies.

    I'm wondering also if seals (viton, buna, PTFE??) have a higher/lower permeability than tires. PTFE for sure is less permeable.

    I think that pressure losses in shocks are for a very different reasons than permeability of sidewall in tires. To begin with, as you know, the shock sleeve (air chamber) slides over the shaft.. that alone can produce more losses than permebility of the seals. Some shocks lose their pressure also while just not working... so the permeability stuff holds water but I think losses are more for the construction of the shock than for permeability.

    I doubt N2 would help much with that. In that case, refilling will be a tad more complicated.
    That makes sense. So much for an easy fix for those sufffering from shock incontinence.
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  20. #20
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    Quote Originally Posted by Appendage
    That makes sense. So much for an easy fix for those sufffering from shock incontinence.
    More on this.... Butyl has a very low permeability and it's used on tires, most tubes are made of it... but they use a nice percentage of natural rubber too and natural rubbers are highly permeable.

    Seals, OTOH, are mostly 100% butyl, Fluorocarbons (Viton) or nitrile based, being all of them less permeable than natural rubber.

    Also, the area exposed to permeation (sp??) is much smaller.... if the seals are to blame for not holding pressure, some other things are to be considered, like shaft roughness and tolerances. So, construction is much more important than gas used in it.

    I gotta accept IR knows some pneumatics.... but comparing the tire to a shock is a bit of a stretch.

    I think that for IFP pistons, N2 is THA thing to use... but for the main spring chamber... uh, I dunno. I think it's not worthy if you're not riding a shock that heats a lot (read: MX).
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  21. #21
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    your seals are bad or your piston shaft is scored.

    maybe the design of the seal itself is inadaquate. for which, why stop at n2? go to a welding supply place, get a can of argon and try that. doubt if atomic size differences will make up for sloppy part tolerances, but have at it.

  22. #22
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    Quote Originally Posted by drunkle
    your seals are bad or your piston shaft is scored.

    maybe the design of the seal itself is inadaquate. for which, why stop at n2? go to a welding supply place, get a can of argon and try that. doubt if atomic size differences will make up for sloppy part tolerances, but have at it.
    Nah!!! That would make the shock heavier!!!
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