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  • Retrorockit
    replied
    AZ is an airplane guy, and needs to know this stuff. Putting the wrong type, or amount of gas in an airplane tire can have consequences.
    "Let's stick to the facts" was your idea Diggs. If this produced more facts than you would like that's too bad.
    "Others don't like to play here" are weasel words.No one is stopping you from going and playing with "others". I suspect there aren't very many.

    Leave a comment:


  • AZguy
    commented on 's reply
    I'm not sure what the problem is - initially I made a very simplistic point about CO2 and pressure changes with temperature when used in tires that was totally on topic, a simplistic reply was made that that response was somehow incorrect and so I got in the weeds since clearly my first comment was overly simplistic

    Is that a bad thing? I suppose the response can be moved to it's own thread if for some reason it seems inappropriate here, but it sure seemed appropriate _and_ civil to me... and who are those "others that don't like to play here"?... there are other electric bike heavy boards with folks that don't hesitate to do far less civil responses in similar cases


    Oh well... can't please everyone...

    Ride on, have fun!

  • Diggs Ut
    replied
    Originally posted by AZguy View Post

    OK, let's stick with the facts =]


    Boyles law and Charles law only apply to "ideal gasses" - which would stay gaseous all the way down to absolute zero at all pressures and temperatures. For real gasses those are only linear (straight line) approximations and the further a gas deviates from "ideal" the less well they apply.

    Gases like oxygen or nitrogen behave much closer to an ideal gas such that those approximations are plenty close enough for normal temperatures and pressures but even those gases will deviate strongly from those approximations at extremes. Those real world gases just plain aren't linear either.

    CO2 even at atmospheric pressure will condense into a solid at about -80°C vs. the ~-273°C (absolute zero) of the ideal gasses those approximations apply to so the scale is already slid by close to 200°K. Not to mention it will condense at room temperature at about 5.8MPa (~830psi absolute, ~815psi gauge) and this drops considerably at colder temperatures further offsetting the bias points in the ideal gas approximation. CO2 is quite non-linear too - it is a very curved line.

    However in the real world on top of all those deviations from ideal gas is that it is very soluble in water and when it dissolves in water that lowers the pressure a *lot* and this is likely going to have an even greater effect than the ideal gas deviations. That solubility is highly dependent on temperature and pressure and very rapidly increases with pressure and decreases very rapidly with temperature, especially when under pressure. Unless you've only used a dry gas to inflate your tires, they will have plenty of moisture in them - nature of the beast. Sealants like stans are full of water too. This will also acidify the moisture and while it's not that acidic (think soda pop acidic) and likely doesn't affect the rubber much, I'm not so sure about the sealants although I'm sure plenty of folks are using CO2 with them, but if it reduces their life at all I'm not on board.

    I've experienced this in the real world. I used to carry CO2 in my off-road vehicles - mostly so we could air way down in sand a then quickly get back up when heading back into the rocks. I've measured how much that pressure with CO2 fluctuates with elevation and temperature changes and it ain't pretty, especially where pressure deviations make a big difference like moto tires. After fighting that I stopped using CO2 in those applications. For the large off-road vehicles I got a high volume electric pump and for motos I took one of those <$20 noisy little 12V diaphragm pumps and took them out of the case - the little pump is really small, fist-sized, so very portable and even though they are very low volume they work pretty well for moto tires and would be great for bike tires if we had 12V handy (someday, someday!). That 48V one that they linked to is likely very small if you take it out of the case.



    Now for the real world of bikes

    For decades riding in the desert full of thorns and other pointy things (just about every creature in the desert is flat out mean, especially plants!) I used to accept a flat every other ride. I was using the CO2 cartridges for a year or two. When I finally graduated to fat tires (4+") they were a lot more hassle. It sometimes took more than one cartridge and when you are out of cartridges you are out of gas so you better have that pump too. And then one time I inadvertently was grabbing a cold part and got a pretty nasty frostbite since it numbed the area so quickly I didn't realize I was getting burned. So I went back to hand pumps and really came to the conclusion after going through plenty of cartridges is that the *only* advantage that the cartridges offered was that they were faster for sure. Even though the pump takes longer (and we're only talking a couple of minutes - real world) it's not a workout (I've done it in >45°C), just a lot of movement - or maybe I'm just in better shape LOL. Pumps are super reliable, will get to whatever pressure you need and does it with air vs. nasty old CO2.




    But anyway to me this is almost a silly discussion. Times have changed. More real world...



    Click image for larger version

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    Dude - Really? No wonder others don't like to play here........

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  • AZguy
    replied
    Originally posted by Diggs Ut View Post

    OK - Lets' stick to the facts. Charles Law states all gases expand with temperature at the same rate. CO2 expands no more and no less than Oxygen, Nitrogen or any other gas. It is also less reactive and corrosive than oxygen when mixed with other elements. My inflator has a thick foam sleeve over it (freezing has never been a problem) and securely threads onto the valve stem before I turn on the variable gas valve to inflate the tire. You guys can pump away with a manual pump on a hot day (never any shade when I had a flat). Your challenge with fat tires is many pumps. My challenge was pumping 75-90 psi. Either way, I'll take the CO2 inflator. Works like a dream, is tiny even with cartridges and I don't even have to raise a sweat. It's hard to believe those that don't like them have even used them. They are better than sliced bread.
    OK, let's stick with the facts =]


    Boyles law and Charles law only apply to "ideal gasses" - which would stay gaseous all the way down to absolute zero at all pressures and temperatures. For real gasses those are only linear (straight line) approximations and the further a gas deviates from "ideal" the less well they apply.

    Gases like oxygen or nitrogen behave much closer to an ideal gas such that those approximations are plenty close enough for normal temperatures and pressures but even those gases will deviate strongly from those approximations at extremes. Those real world gases just plain aren't linear either.

    CO2 even at atmospheric pressure will condense into a solid at about -80°C vs. the ~-273°C (absolute zero) of the ideal gasses those approximations apply to so the scale is already slid by close to 200°K. Not to mention it will condense at room temperature at about 5.8MPa (~830psi absolute, ~815psi gauge) and this drops considerably at colder temperatures further offsetting the bias points in the ideal gas approximation. CO2 is quite non-linear too - it is a very curved line.

    However in the real world on top of all those deviations from ideal gas is that it is very soluble in water and when it dissolves in water that lowers the pressure a *lot* and this is likely going to have an even greater effect than the ideal gas deviations. That solubility is highly dependent on temperature and pressure and very rapidly increases with pressure and decreases very rapidly with temperature, especially when under pressure. Unless you've only used a dry gas to inflate your tires, they will have plenty of moisture in them - nature of the beast. Sealants like stans are full of water too. This will also acidify the moisture and while it's not that acidic (think soda pop acidic) and likely doesn't affect the rubber much, I'm not so sure about the sealants although I'm sure plenty of folks are using CO2 with them, but if it reduces their life at all I'm not on board.

    I've experienced this in the real world. I used to carry CO2 in my off-road vehicles - mostly so we could air way down in sand a then quickly get back up when heading back into the rocks. I've measured how much that pressure with CO2 fluctuates with elevation and temperature changes and it ain't pretty, especially where pressure deviations make a big difference like moto tires. After fighting that I stopped using CO2 in those applications. For the large off-road vehicles I got a high volume electric pump and for motos I took one of those <$20 noisy little 12V diaphragm pumps and took them out of the case - the little pump is really small, fist-sized, so very portable and even though they are very low volume they work pretty well for moto tires and would be great for bike tires if we had 12V handy (someday, someday!). That 48V one that they linked to is likely very small if you take it out of the case.



    Now for the real world of bikes

    For decades riding in the desert full of thorns and other pointy things (just about every creature in the desert is flat out mean, especially plants!) I used to accept a flat every other ride. I was using the CO2 cartridges for a year or two. When I finally graduated to fat tires (4+") they were a lot more hassle. It sometimes took more than one cartridge and when you are out of cartridges you are out of gas so you better have that pump too. And then one time I inadvertently was grabbing a cold part and got a pretty nasty frostbite since it numbed the area so quickly I didn't realize I was getting burned. So I went back to hand pumps and really came to the conclusion after going through plenty of cartridges is that the *only* advantage that the cartridges offered was that they were faster for sure. Even though the pump takes longer (and we're only talking a couple of minutes - real world) it's not a workout (I've done it in >45°C), just a lot of movement - or maybe I'm just in better shape LOL. Pumps are super reliable, will get to whatever pressure you need and does it with air vs. nasty old CO2.




    But anyway to me this is almost a silly discussion. Times have changed. More real world...

    I moved on to using tubeless sealant aend even riding in the AZ desert haven't had a flat in >9000mi over several years (touch wood) so just leaving a good pump (as mentioned I'm a big fan of lezyne) strapped to the bike frame seems appropriate, especially considering how seldom it sees use - almost always just to help a nice young lady with a flat. Click image for larger version

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    Ride on!


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  • Diggs Ut
    replied
    Originally posted by AZguy View Post
    CO2 is one of the worst gasses to inflate tires with too. It changes pressure with heat
    OK - Lets' stick to the facts. Charles Law states all gases expand with temperature at the same rate. CO2 expands no more and no less than Oxygen, Nitrogen or any other gas. It is also less reactive and corrosive than oxygen when mixed with other elements. My inflator has a thick foam sleeve over it (freezing has never been a problem) and securely threads onto the valve stem before I turn on the variable gas valve to inflate the tire. You guys can pump away with a manual pump on a hot day (never any shade when I had a flat). Your challenge with fat tires is many pumps. My challenge was pumping 75-90 psi. Either way, I'll take the CO2 inflator. Works like a dream, is tiny even with cartridges and I don't even have to raise a sweat. It's hard to believe those that don't like them have even used them. They are better than sliced bread.

    Leave a comment:


  • AZguy
    commented on 's reply
    I think that 48V pump makes a lot more sense than a rechargeable one for nearly all electric bike applications, Much more than CO2 since size and weight are less an issue.

    My reality is that I just don't need a pump for >99.9% of riding. I haven't needed to use a pump trailside in years after sealing the tires. So I'll carry one like carrying a spare tire in the car which in all reality likely get used more and I still don't bother to carry a bottle jack and real tire (I do in the 4x4 but that's different). I guess if I were riding more deep in the backcountry, particularly solo, I might go back to carrying a patch kit too I guess - or better yet go fully tubeless and just carry a plug kit.

    Now if I were going to be changing tires pressures a lot, say to run deep sugar sand and then go back to pointy rock territory perhaps an electric would make more sense for my use cases

    In the end I have to ask in these days where sealing a tire is tried, true and pretty darn painless, what is someone doing wrong that they need a pump more than every fifth blue moon?

    YMMV

  • 73Eldo
    commented on 's reply
    Interesting, looks to be about $40.

  • Fred
    commented on 's reply
    Here's one that runs at 48V. May be a bit bulky for some.

  • TNC
    replied
    I hate CO2 stuff too. I use a Topeak Mountain Morph. It's like a small floor pump with a little foot that you can fold out and step on. It's much easier than having to do the isometric exercise of a hand pump. It always works, and I don't have to worry about whether I have enough CO2.

    MOUNTAIN MORPH® | Topeak

    Leave a comment:


  • 73Eldo
    commented on 's reply
    Battery death from non use was the first thing that popped into my mind. Someone needs to build one that can run in the 48-52 range so we can run it direct off out packs if needed.

  • AZguy
    commented on 's reply
    I think the rechargeable would be ok, albeit sort of heavy and large, only if you use them often

    If they only get used once a year or so (my carry pump likely doesn't even see that) then it would just be a battery you have to maintain and since they'd be kept charged, likely would get few cycles from them - now running a pump from the bike battery would make a lot more sense for that occasional use I think

  • Retrorockit
    commented on 's reply
    I did see a bunch of small rechargeable tire inflators available. IDK anything about them.But looks like better option than manual pumps or CO2.
    My NOX cartridges don't have threaded ends, so I guess I'll just have to save them for my whippet powered Iced coffee dispenser.

  • Fred
    replied
    One of these is another possibility; a little bigger than a small pump, but mine works well. I imagine one coud recharge it (12V) on the road with an inverter or srep-down transformer off the ebike battery,

    Leave a comment:


  • AZguy
    replied
    That looks skinny for fat tires

    A bit more money but looks a lot better for fat and I'm a huge fan of lezyne pumps: https://ride.lezyne.com/collections/...tubeless-drive

    Leave a comment:


  • 73Eldo
    replied
    This looks maybe interesting. Looks like its a Co2 head that says it threads onto the valve but they added a pump attachment with the same thread as the canisters.

    Shopping for mini bike pumps? Check out Blackburn's Core CO2'Fer Mini Bike Pump to ensure that every ride is safe and enjoyable. Shop online today.

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