Best CO2 inflators: Fast tyre inflation in small packages

These little gizmos are excellent if you want to pump up your tyres FAST. They're incredibly simple, all of them act as a valve. Screw a CO2 canister on one end, screw the other onto your valve and either turn a knob or just press down and with a short blast of pressurised gas, you're good to go. Unless you're racing and need the smallest, lightest setup possible, then I see them as an accompaniment to, rather than a replacement for the best bike pumps though we have discussed which is best. That being said, even the best gravel tyres sometimes unseat if they go flat, and a blast of carbon dioxide is far more likely to reseat them than your frantic pumping.

The best CO2 inflators you can buy today

Given the simplicity of these products, there's a lot less differentiation between them, and they all achieved the desired outcome of popping air into my tyres. The ones without valves tended to over-inflate, but then you just let a bit out from the tyre when you're done. There are a few with special features like gauges, and many come with a protective sleeve as the Joule-Thomson effect (a change of temperature from the expansion of gasses) makes them frost up when in use, but in short all of them work well enough that you really can pick what you fancy without fear.

How to choose

Still a bit unsure as to what you're after? Worry not, I've got you covered. Whether you want to know more about how to use CO2 inflators, or simply aren't quite sure what they are as yet then scroll down and have a read of my curated FAQ's.

What are CO2 inflators?

In the basic sense they're simply a small canister of compressed carbon dioxide that is delivered to your tyre via a valve head. There are variations on the theme but they all aim to do the same thing. Nearly all use threaded cartridges, so that’s all we’ve featured here, which come in either 16g or 25g varieties.

The two basic types are inline, whereby the cartridge is in line with the valve and actuated by pressing down, and angled types where the valve head forms a 90-degree angle and the canister will stick out sideways from the rim when in use. There’s no great difference between the two, but if you’ve got small wheels and lots of spokes then an angled one might be easier for you to use.

How many cartridges does it take to fill up a tyre?

For road tyres, a single 16g cartridge is sufficient for reinflation and will get it up to and over your desired pressure with ease. You may end up over-inflating and having to back off.

For larger volume tyres, we’re talking gravel bikes here, we’d go for a larger 25g cartridge. While you may have the volume within a 16g for reinflation, you may not be able to reach sufficient pressure to reseat your tubeless tyres, which would leave you in a pickle.

Can I use a CO2 inflator with tubeless tyres

On the whole, yes, though some sealants do say not to. The issue comes with the freezing effect of releasing compressed gas, which can freeze your sealant solid, rendering it useless. The best practice is to rotate the valve to the uppermost point and inflate from there, allowing the liquid sealant to drain to the bottom, as far away from the icy blast as possible. 

Are CO2 cartridges single use?

Yes, once they’re installed in the head they’re basically a disposable item. Once your tyre is back on you’ll probably want to vent the remainder of the canister by pressing the head against something (not your finger!) or opening the valve. If you unthread the cartridge without doing this you’ll spray gas everywhere in an uncontrolled way, and if you stow it away without venting the remainder it could end up venting itself in your jersey pocket.

This also means that for longer rides you may want to carry a couple of spare cartridges in case the worst happens.

What can I do with the cartridges after use?

They're made of aluminium, so can be recycled however you currently recycle your aluminium. Please don't leave them on the road or the trailside though.

Does CO2 leak out of bike tyres?

Carbon dioxide is a smaller molecule than the mix of molecules in the air which normally goes into your tyres. As such it seeps through the rubber of a tyre more easily and will go flat faster. It won’t go down immediately, but you will notice it the next day. Our advice would be not to rely on CO2 for multi-day events, and if you do have to use a CO2 inflator then deflate your tyres when you get home and refill from a standard pump. 

How we test

We’ve used plenty of CO2 inflators here at Cyclingnews so we know what to look for in terms of ease of use, thermal protection, gas delivery modulation and overall build quality.

For this grouptest we used the same tyre each time to avoid any differences in the valve, and always started from totally flat. The tyre in question was a Challenge Strada 27mm, which can be a little tricky to reseat so it makes an ideal test subject.

Will Jones
Tech Writer

Will joined the Cyclingnews team as a reviews writer in 2022, having previously written for Cyclist, BikeRadar and Advntr. There are very few types of cycling he's not dabbled in, and he has a particular affection for older bikes and long lasting components. Road riding was his first love, before graduating to racing CX in Yorkshire. He's been touring on a vintage tandem all the way through to fixed gear gravel riding and MTB too. When he's not out riding one of his many bikes he can usually be found in the garage tinkering with another of them, or getting obsessive about tyres. Also, as he doesn't use Zwift, he's our go-to guy for bad weather testing... bless him.

Rides: Custom Zetland Audax, Bowman Palace:R, Peugeot Grand Tourisme Tandem, Falcon Explorer Tracklocross, Fairlight Secan & Strael