Advertise on Bikeforums.net



User Tag List

Page 1 of 3 123 LastLast
Results 1 to 25 of 68
  1. #1
    Senior Member
    Join Date
    Dec 2010
    Location
    Moray , North East Scotland
    My Bikes
    531 Harry Hall/late seventies . Giant trance 3. Sabbath Silk Road Ti.d
    Posts
    102
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Nitrogen build up in tires

    It occurred to me that as nitrogen has larger molecules than oxygen and carbon dioxide,and that inner tubes leak the smaller molecules out through the rubber,that as the inner tube is re inflated over an extended period then the ratio of nitrogen ,to other gasses found in normal air, will increase and the larger nitrogen molecules don't pass freely through the inner tube wall.
    To that end,does it seem to you cyclists out there ,that the longer an inner tube is in use ,the less frequently it needs to be re inflated ?
    It may be my imagination ,but unless I have a faulty valve ,after the first few times I pump up my tires they seem to stay up almost indefinitely.
    .

  2. #2
    Senior Member
    Join Date
    Sep 2003
    Location
    Allen, TX
    My Bikes
    Look 585
    Posts
    1,340
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    hair∑split∑ting (h‚rspltng)
    n.
    The making of unreasonably fine distinctions.

  3. #3
    Senior Member
    Join Date
    Jun 2009
    Posts
    707
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Drumnagorrach View Post
    It occurred to me that as nitrogen has larger molecules than oxygen and carbon dioxide,and that inner tubes leak the smaller molecules out through the rubber,that as the inner tube is re inflated over an extended period then the ratio of nitrogen ,to other gasses found in normal air, will increase and the larger nitrogen molecules don't pass freely through the inner tube wall.
    To that end,does it seem to you cyclists out there ,that the longer an inner tube is in use ,the less frequently it needs to be re inflated ?
    It may be my imagination ,but unless I have a faulty valve ,after the first few times I pump up my tires they seem to stay up almost indefinitely.
    .
    Filling tires with nitrogen gas was a retail tire chain scam. The so called better air contention is rediculous
    If the air container being the tire and the sealed wheel has integrity it is not going to leak signifigantly no matter what kinda air is in the tire. There has been studies that support this,,that is why you see less and less of nitrogen filling being promoted.

  4. #4
    Ding! Bandera's Avatar
    Join Date
    Mar 2013
    Location
    Texas Hill Country
    Posts
    1,783
    Mentioned
    9 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Drumnagorrach View Post
    It occurred to me that as nitrogen has larger molecules than oxygen and carbon dioxide,and that inner tubes leak the smaller molecules out through the rubber,that as the inner tube is re inflated over an extended period then the ratio of nitrogen ,to other gasses found in normal air, will increase and the larger nitrogen molecules don't pass freely through the inner tube wall.
    To that end,does it seem to you cyclists out there ,that the longer an inner tube is in use ,the less frequently it needs to be re inflated ?
    It may be my imagination ,but unless I have a faulty valve ,after the first few times I pump up my tires they seem to stay up almost indefinitely.
    .
    Nice.....
    '74 Raleigh International - '77 Trek TX900FG - '92 Vitus 979 - '10 Merckx EMX-3- '11 Soma Stanyan

  5. #5
    Senior Member Homebrew01's Avatar
    Join Date
    Jul 2004
    Location
    Ffld Cnty Connecticut
    My Bikes
    Old Steelies I made, Old Cannondales
    Posts
    15,802
    Mentioned
    6 Post(s)
    Tagged
    1 Thread(s)
    The high concentration of nitrogen is the reason I never use my bicycle wheels for supplementary air while scuba diving.
    Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike

  6. #6
    Senior Member Flying Merkel's Avatar
    Join Date
    Mar 2008
    Location
    Costa Mesa CA
    Posts
    2,541
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Semi-permeable membrane. The theory is spot on, the actual is not.
    Pronounced "Murkle"

  7. #7
    Senior Member
    Join Date
    Nov 2008
    Location
    Bay Area, Calif.
    Posts
    4,890
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Flying Merkel View Post
    Semi-permeable membrane. The theory is spot on, the actual is not.
    Agreed. Yes, N2 diffuses through tubes a little slower than O2, but the difference is small and air is 78% nitrogen anyway so the effect is negligible. BTW, the difference is not due to size but rather that oxygen is more reactive with the hydrocarbon molecules of rubber and therefore tends to stick to the inner surface of the tube and then gradually diffuses through it - CO2 clings even more and diffuses much faster despite being a larger molecule.
    Last edited by prathmann; 11-25-13 at 08:12 AM.

  8. #8
    Lover of Old Chrome Moly Myosmith's Avatar
    Join Date
    May 2011
    Location
    NW Minnesota
    Posts
    2,544
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    What the heck . . . I might as well throw this out there

    If CO2 diffuses through an inner tube the fastest and N2 the slowest of the common gases, then why don't we use nitrogen cartridges in our inflators? The technology is readily available and they already make such cartridges for the food and beverage industry. When you look online the N2 cartridges are very expensive but remember that they must pass food grade standards and are a specialty item. If you wanted to produce bulk numbers of nitrogen cartridges for bike tire inflators, you could fill the same cartridges as we use for CO2 with industrial N2 for about the same price.
    Last edited by Myosmith; 11-24-13 at 08:28 PM.
    Lead, follow or get out of the way

  9. #9
    Senior Member
    Join Date
    Sep 2012
    Location
    Orange County, California
    Posts
    235
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    The only advantage to using pure nitrogen instead of air is nitrogen is dry. Straight air still has water vapor in it, and that can build up in auto tires causing corroded rims and changes in tire pressure as the vapor heats up while driving. Same thing in bicycle tires.


    Carbon Dioxide cartridges - Carbon dioxide is one of those odd gases that goes into liquid under (relatively) low pressure (like refrigerant gases, propane, ammonia), so its easy to put enough into a small cylinder to fill a bike tire. Try putting the same amount of nitrogen in one of those small cylinders and it would be under astounding pressure, making it somewhat dangerous for the average rider to use.
    Are we having fun yet?

  10. #10
    Senior Member wahoonc's Avatar
    Join Date
    Jan 2005
    Location
    On the road-USA
    My Bikes
    Giant Excursion, Raleigh Sports, Raleigh R.S.W. Compact, Motobecane? and about 20 more! OMG
    Posts
    16,277
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    I would use helium to make the bike lighter

    Aaron
    Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(

    ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.

    "Cycling should be a way of life, not a hobby.
    RIDE, YOU FOOL, RIDE!"
    _Nicodemus

    "Steel: nearly a thousand years of metallurgical development
    Aluminum: barely a hundred
    Which one would you rather have under your butt at 30mph?"
    _krazygluon

  11. #11
    Senior Member Retro Grouch's Avatar
    Join Date
    Feb 2004
    Location
    St Peters, Missouri
    My Bikes
    Rans Enduro Sport, Hase Kettweisel Tandem, Merin Bear Valley beater bike
    Posts
    23,899
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Now see - it's threads like this one that make me glad I'm a retro grouch. One more thing that I don't worry or even think about.
    My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.

  12. #12
    rugged individualist wphamilton's Avatar
    Join Date
    Apr 2011
    Location
    Alpharetta, GA
    My Bikes
    Nashbar Road
    Posts
    6,307
    Mentioned
    20 Post(s)
    Tagged
    0 Thread(s)
    It's been suggested that permeability declines with the age of rubber, so maybe your tubes are just getting old. But the downside to that is it gets brittle so that's probably not it

    Yet I was just thinking about it last week, and it seems to me that a patch is going to be more air-tight than the bare tube, being thicker and with the vulcanizing. So the more the tube is patched, the better it will hold air - eventually my tube will be covered entirely and I might never have to add air.

  13. #13
    New Orleans
    Join Date
    Jan 2006
    Posts
    2,512
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    Makes sense-sound theory
    doesn't matter
    because the increase in concentration and the actual difference in loss N VS O2 is TINY
    Guessing lots of the actual loss is from "holes" and faulty valves big enough to pass either molecule easily enough

    Besides the N2 is slightly less massive than O2-
    so it is going faster-which means it might strike the inner tube"holes" more often(this is an off the cuff guess-so maybe wrong)
    Last edited by phoebeisis; 11-25-13 at 10:28 AM.

  14. #14
    coprolite fietsbob's Avatar
    Join Date
    Jun 2010
    Location
    NW,Oregon Coast
    My Bikes
    7
    Posts
    1,571
    Mentioned
    34 Post(s)
    Tagged
    0 Thread(s)
    at 250+mph maybe oxygen deprived tires wont catch fire..

  15. #15
    Mad bike riding scientist cyccommute's Avatar
    Join Date
    Nov 2004
    Location
    Denver, CO
    My Bikes
    Some silver ones, a black one, a red one, an orange one and a couple of titanium ones
    Posts
    15,734
    Mentioned
    18 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Drumnagorrach View Post
    It occurred to me that as nitrogen has larger molecules than oxygen and carbon dioxide,and that inner tubes leak the smaller molecules out through the rubber,that as the inner tube is re inflated over an extended period then the ratio of nitrogen ,to other gasses found in normal air, will increase and the larger nitrogen molecules don't pass freely through the inner tube wall.
    To that end,does it seem to you cyclists out there ,that the longer an inner tube is in use ,the less frequently it needs to be re inflated ?
    It may be my imagination ,but unless I have a faulty valve ,after the first few times I pump up my tires they seem to stay up almost indefinitely.
    If you were to fill the tube with equal amounts of nitrogen and oxygen, the oxygen would diffuse out faster than the N2. But the problem is that, in an atmospheric mixture of O2 and N2, you have a partial pressure of N2 that is almost 4 times that of O2. The nitrogen's diffusion rate is slower but it is the driving force behind the diffusion. The loss of N2 is about equal to the loss of O2 in this polymer.

    When you fill the tube entirely with carbon dioxide, the diffusion rate of the CO2 is very high and it is the only gas present in the rubber. Thus the CO2 diffuses out very quickly. In an atmospheric mixture the amount of CO2 is exceedingly tiny and has no effect on the diffusion of the gas out of the tube.



    Quote Originally Posted by Myosmith View Post
    What the heck . . . I might as well throw this out there

    If CO2 diffuses through an inner tube the fastest and N2 the slowest of the common gases, then why don't we use nitrogen cartridges in our inflators? The technology is readily available and they already make such cartridges for the food and beverage industry. When you look online the N2 cartridges are very expensive but remember that they must pass food grade standards and are a specialty item. If you wanted to produce bulk numbers of nitrogen cartridges for bike tire inflators, you could fill the same cartridges as we use for CO2 with industrial N2 for about the same price.
    The "nitrogen" cartridges for the food industry aren't nitrogen. They are nitrous oxide or N2O. N2 can be made into a liquid form and will remain a liquid if kept cold but warm it up a little and it boils off. You can't compress enough N2 gas to put it in a tiny little cylinder like we use for bikes. CO2 can be compressed into a liquid and kept there at room temperature (and somewhat above) without refrigeration so you can put it into the little cylinders.

    You don't want to be using nitrous oxide for much of anything, by the way. I sure that the "nitrogen" cartridges used in the food industry are low pressure since you don't want to blow out the foam too quickly. Nitrous oxide is a hell of an oxidizer as well. You can make a natural gas or just about any hydrocarbon gas burn much more intensely with N2O. It packs a wallop.
    Stuart Black
    Solo Without Pie. The search for pie in the Midwest.
    Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
    Days of Wineless Roads. Bed and Breakfasting along the KATY
    Twisting Down the Alley. Misadventures in tornado alley.
    An Good Ol' Fashion Appalachian Butt Whoopin'.

  16. #16
    Senior Member
    Join Date
    Aug 2009
    Location
    North of Boston
    My Bikes
    Kona Dawg, Surly 1x1, Karate Monkey, Rockhopper, Crosscheck , Burley Runabout,
    Posts
    1,979
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    They use it for truck tires to run cooler?

  17. #17
    Pedaled too far. Artkansas's Avatar
    Join Date
    Oct 2005
    Location
    La Petite Roche
    Posts
    12,264
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by wahoonc View Post
    I would use helium to make the bike lighter

    Aaron
    Better buy now. We're having a helium shortage.
    "He who serves all, best serves himself" Jack London

    Quote Originally Posted by Bjforrestal View Post
    I don't care if you are on a unicycle, as long as you're not using a motor to get places you get props from me. We're here to support each other. Share ideas, and motivate one another to actually keep doing it.

  18. #18
    Senior Member BlazingPedals's Avatar
    Join Date
    Dec 2004
    Location
    Middle of da Mitten
    My Bikes
    Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, homebuilt recumbent
    Posts
    7,229
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    I like pie!!!

  19. #19
    rebmeM roineS JanMM's Avatar
    Join Date
    Jan 2006
    Location
    Indiana
    My Bikes
    RANS V3, RANS V-Rex, RANS Screamer
    Posts
    11,677
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by BlazingPedals View Post
    I like pie!!!
    Nitrous oxide propels the whipped cream onto your pie........................
    RANS V3 (steel), RANS V-Rex, RANS Screamer

  20. #20
    Senior Member longbeachgary's Avatar
    Join Date
    Sep 2008
    Location
    Beautiful Long Beach California
    My Bikes
    Eddy Merckx MXL; 2012 CAAD10; 2013 CAAD10 - The Silver and Black; Cannondale CAAD10 DI2 - The Black Dahlia; 2013 Cannondale CAAD10 DI2, The Black Mambo
    Posts
    3,273
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    You people are too smart for your own good.

  21. #21
    Senior Member
    Join Date
    Sep 2006
    Posts
    460
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Type Permeability of Rubber to Air in GOOGLE and check what shows up.

  22. #22
    Lover of Old Chrome Moly Myosmith's Avatar
    Join Date
    May 2011
    Location
    NW Minnesota
    Posts
    2,544
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Thanks for the good information. I should have remembered that the food dispensing cartridges were N2O as I can remember stories about kids huffing the gas off of canned whipped cream.

    http://www.press-citizen.com/article...S01/104260311/

    http://abcnews.go.com/Blotter/danger...ry?id=16006130
    Lead, follow or get out of the way

  23. #23
    Senior Member
    Join Date
    Dec 2010
    Location
    Moray , North East Scotland
    My Bikes
    531 Harry Hall/late seventies . Giant trance 3. Sabbath Silk Road Ti.d
    Posts
    102
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Well that was interesting,it all started when out on a club run,I find that pedaling hard frees off my mind ,lets it explore and inquire about trivial stuff ,like " do my tires act like nitrogen generators?. So I guess the answer is NO?
    I used to be a maintenance engineer in a food factory,there was a nitrogen generator in one of the plant rooms,we found that as it exhausted the waste gas into the room ,then a gas meter( something we used to check for flammability and breath-ability in the local atmosphere )would often show O2 at over the normal 20.9 % In the initial briefing on the generator ,I was told by the makers that it worked on the principle of N2 molecules not passing out through a membrane,all the other gasses did ,the remaining N2 was then pumped out to a receiver and the cycle began again. Thats what started that chain of thought.

  24. #24
    Senior Member avmech's Avatar
    Join Date
    Apr 2011
    Location
    Jupiter Florida
    Posts
    197
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by skidder View Post
    The only advantage to using pure nitrogen instead of air is nitrogen is dry. Straight air still has water vapor in it, and that can build up in auto tires causing corroded rims and changes in tire pressure as the vapor heats up while driving. Same thing in bicycle tires.
    Reason we use it in airplane tires and shock struts.
    2003 Trek 5200
    2012 Trek 7500

  25. #25
    coprolite fietsbob's Avatar
    Join Date
    Jun 2010
    Location
    NW,Oregon Coast
    My Bikes
    7
    Posts
    1,571
    Mentioned
    34 Post(s)
    Tagged
    0 Thread(s)
    I am not cycling at 3 miles up. in the jetstream..

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •