Noob question re CO2 inflators

Mububban
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Noob question re CO2 inflators

Postby Mububban » Wed Oct 26, 2016 12:18 pm

When changing tubes on a road bike, should you partially inflate the tube using a mini pump and then use a CO2 cartridge to get up to full pressure, or just use the CO2 from flat?

I'm wondering if a partial pump then CO2 will over-inflate and pop the tube, or will it just stop when it hits a certain pressure?

I'm riding 25mm and have 16g cartridges.
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biker jk
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Re: Noob question re CO2 inflators

Postby biker jk » Wed Oct 26, 2016 1:45 pm

I use a mini pump to give the tube some shape to make installation easier. The Co2 inflator will get you to over 100psi but you can shut it off before it completely empties. In a 25mm tyre you won't need more than 90psi absolute maximum in any case. Why waste the Co2 inflator to give the tube some shape then risk not having enough Co2 left to properly inflate the tube?

vosadrian
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Re: Noob question re CO2 inflators

Postby vosadrian » Wed Oct 26, 2016 1:54 pm

I just blow some air in with my mouth to give it some shape to stop any kinks in the tube when fitting. You should be able to get the tube to take shape using just your lungs. If I am carrying CO2 I generally don't carry a pump. Then I fit tube and release about 20psi worth and check everything is seated right (have had tyre beads not seat before causing instant tube failure when CO2 released). Then release the rest. This generally gets too much pressure in a 23mm tyre which can be an issue if riding in the wet/slippery conditions. Some of my wheels like at least about 120psi sometimes to seat the bead properly so better to over pressure and then let some out if too hard, but in the dry/grippy conditions I just ride with hard tyres until I can check properly.
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Gerry.M
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Re: Noob question re CO2 inflators

Postby Gerry.M » Wed Oct 26, 2016 2:27 pm

vosadrian wrote:I just blow some air in with my mouth to give it some shape to stop any kinks in the tube when fitting. You should be able to get the tube to take shape using just your lungs. If I am carrying CO2 I generally don't carry a pump. Then I fit tube and release about 20psi worth and check everything is seated right (have had tyre beads not seat before causing instant tube failure when CO2 released). Then release the rest. This generally gets too much pressure in a 23mm tyre which can be an issue if riding in the wet/slippery conditions. Some of my wheels like at least about 120psi sometimes to seat the bead properly so better to over pressure and then let some out if too hard, but in the dry/grippy conditions I just ride with hard tyres until I can check properly.

^ This - it's pretty easy to blow a little bit of air using your mouth into the tube to give it some shape

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outnabike
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Re: Noob question re CO2 inflators

Postby outnabike » Wed Oct 26, 2016 5:24 pm

I've stopped twice to help different riders, and pumped up their tyres. Mind you I am in no hurry if a bloke is in need. One was a racing bike the other a bso. The full CO2 cartridge did them both and no complaints. :)
Mind you I only did the thumb test and had no complaints.

Interestingly I have not used the thing on my own bike yet.....fingers crossed.
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vosadrian
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Re: Noob question re CO2 inflators

Postby vosadrian » Thu Oct 27, 2016 9:25 am

outnabike wrote:I've stopped twice to help different riders, and pumped up their tyres. Mind you I am in no hurry if a bloke is in need. One was a racing bike the other a bso. The full CO2 cartridge did them both and no complaints. :)
Mind you I only did the thumb test and had no complaints.

Interestingly I have not used the thing on my own bike yet.....fingers crossed.


One cartridge will certainly get two 23mm road tyres ridable... but it would not get two up to optimal pressure. I have had two flats with one cartridge and the second time got me to 30-40psi which was enough to get home but it did not feel too good. If I had put less pressure in the first time, I probably could have got two tyres to around 70-80psi which would have been OK.
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Duck!
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Re: Noob question re CO2 inflators

Postby Duck! » Fri Oct 28, 2016 1:40 pm

You need to get some air into the tube by some means before fitting it in the tyre to avoid pinching it when installing the tyre.

Always carry a pump as well; if you have a bad day & have more punctures than you have canisters, you can still get yourself going.

Another thing to note, tyres inflated with CO2 will deflate quicker than with natural air; by chemical trickery the gas is absorbed into and passes through the tube membrane at a much faster rate than air does.
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