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I used to ride a 26" mtb, but now I'm switching to a 29er. Since the volume of the tire increases, I was wondering is one 16 gram CO2 cartridge enough to inflate the tire?

Notes: The tire will be between 2.1 and 2.25 wide. Since I'm big (110 kg) I need more pressure as a low weight biker.

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2 Answers

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Yes. One 16 gram cartridge is enough to fill an average 29" tire. I just tested in my Schwalbe Rocket Ron 29x2.25, and from empty it gets to about 38 psi. I run tubeless, so normal pressure at my 110kg weight is around 35-38psi.

With a tubed setup, 38psi might be a touch low, but plenty to get you back in off the trail.

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up vote 5 down vote

I found this chart which lists tyre pressure for various sizes of tyres and cartridges. It doesn't list 29 inch tyres, but with a little bit of maths and physics (and a little bit of hand-waving) I calculate that the pressure in a 29 inch tyre is going to be about 10% lower than a 26 inch tyre.

The chart says 40 psi for a 26 inch tyre, so you'd be looking at about 36 psi for a 29 inch tyre. Which is a bit on the low side.

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Unfortunately, that chart isn't particularly useful. 27"/700C tires range from under an inch width to about 2", and the volume is a function of the square of the width, so that's a 4x difference. – Daniel R Hicks May 27 '12 at 20:20

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