What are advantages and disadvantages of CO2 inflators over frame pumps?

  • I have a frame pump that I've used on the road when replacing flats, but I always see CO2 inflators advertised at bike shops. Are they worthwhile for the potential weight savings?

    I won't add this as an answer because I'm not positive it's the case, but I _think_ a tire inflated with a CO2 inflater will deflate quicker, because of the increased difference in partial pressure of CO2 between the inside and outside of the wheel. This depends on how permeable CO2 is through rubber, though - it could very well be the reverse.

    I generally don't see the point of CO2 inflators, but I did encounter one use for them recently. I had a flat and attempted to reinflate the leaky tire with my hand pump in 95F weather, in order to make the last mile home. With the CO2 inflator I'd have known right away, without much effort, that it was a lost cause, vs working up an additional useless sweat with the hand pump.

    @freiheit Just a minor quibble with your answer. CO2 is _not_ a smaller molecule than N2. It does leak out, though, due to the partial pressure difference between the inside and outside of the (slowly) permeable tyre. :-)

    i believe that the best realisation for co2 canisters are for city bikers who park up over a day.. Who would want to steal a bike with flat tyres or goto the hassle of pumping up then stealing! Deflate your tyres, park and lock and re-inflate when you come back after work or doing what ever you were doing without a worry! What we would need to do is design a unique nozzle for each valve, kind of like a key that fits in a lock.. that way not anyone with a canister could do the same and still steal..!

    @DonaldRoss That would be some expensive theft prevention if you need one (or even more) CO2 canister per day. Above that it doesn't look as if your answer doesn't try to answer the question, if the CO2 inflators are worth the weight savings.

    why is this not community wiki?

    Whatever you decide, it's important to feel competent and comfortable using what you carry with you. I have used hand pumps and sat on the curb for what felt like hours trying to pump up a tire. So if you get a hand pump, make sure you've practiced using it and know what it takes to actually fill your tire.

  • freiheit

    freiheit Correct answer

    11 years ago


    • Fast - generally these fill up your tire much faster than you could with a pump

    • Less effort - hook up, push button, no pumping

    • Possibly less weight (but I haven't compared weight of smallest pumps to CO2)

    • Lower initial investment - a valve and 2 cartridges generally seems to be cheaper than a good small pump.


    • Consumable cartridges - which is a cost issue if you have to fill up often

    • No backup - if you patch a flat and don't get it quite right, you don't have a way to fill up anymore. You could carry extra CO2 cartridges, but then you could lose the weight advantage.

    • Limited on what tires they work with. Big tires will get less pressure.

    • Less friendly - if your friend gets a flat and you've got one cartridge, will you loan it? If you've got a pump it's no problem at all. I've helped out complete strangers with my pump before.

    • Goes low faster. CO2 seeps through the tube a bit faster than air, so you'll have to top off the tire sooner than if you'd used a pump.

    One possibility to consider is a combo unit. Generally the pump on those is terrible, but it should be enough to get you home if you run out of CO2. Or carry both a pump and a CO2 valve and a cartridge. That way your first flat can be fixed super-fast and you avoid all the disadvantages (and the weight of a simple valve and one cartridge isn't much).

    This fits pretty well with my experience. Nice answer!

    Another potential disadvantage: it's very possible to explode the inner tube when using the CO2 cartridges on a road bike. I have done this before, and then you are out of air, and the tube is completely destroyed (you can't patch it).

    +1 Kevin. So you should also have a seat bag with a spare inner tube. Over the years my bag has grown with its contents; a couple of gels, a couple of CO2 cartridges, multitool, photocopy of my driver's license (so I don't need a wallet in my jersey), $20 bill just in case.

    Yep, I generally have at least two spare tubes. Patching a tube on the shoulder in the cold rain or hot sun is not something I enjoy.

    FWIW, you can inflate mountain bike tires with 12-16g CO2 cartridges without issue. I've also used them for cross tires. The increased volume of air is usually covered since you are not inflating to the same pressure.

    A standard cartridge is good for 45 psi on a 26x2.1 MTB tire. It's more volume, but less pressure, so it still works. Other than that one thing, great answer.

    Depending on your frame, you can get a full sized frame pump which greatly cuts down the time for inflation (relative to the mini pumps which are often sold these days) and reduces the risk of ripping off a valve with furious pumping (unless you have one of those mini ones with a little hose to the valve, like the Lezynes). Carrying both does hedge your risk better than either alone though.

    you can get different sized cartridges according to which size tyre you have. For example I need the biggest cartridge I could find for my 29x2.2 tyre.

    I have a Topeak hybrid HP which acts as a CO2 inflater and a minpump.

    Good answer. I'll add my advantage : CO2 is more compact and out of sight. I can easily fit the CO2 in my saddle bag; the pump would have to be on the frame, which I don't think looks good on a road bike (in my opinion). It's also recommended to have two CO2 cartridge in case you mess something up with the first one or if you have a second flat.

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Content dated before 7/24/2021 11:53 AM