Not sure about using a Co2 Cartridge I have a road bike (Cannondale Synapse Alloy 6). I bought it this past March. In addition, I purchased an inflator. It came with, I presume, a 16g cartridge. I haven't had the need to use this yet. I understand that one of these can put 130lb of pressure in a 27" tire. My tires are designed to hold 105-110lb. I don't want to overinflate my tire. How do I know when I've put 110lb of air in my tire? With my floor pump, this is no problem. I set the pump to 110 and I can't put more in when I reach this amount. I don't want to blow my tire out with one of these cartridges.

Thanks for your help.
These cartridges are intended to inflate a tire in an emergency situation, like during a race, or for example during a ride on the country-side, far away from gas stations ;o)

(or, by the way, just to save your arm muscles from inflating a skinny tire up to a very high pressure)

When they say "up to 130 PSI", I think the manufacturers want the potential customers to be sure that the product actually might achieve 130 PSI if needed. For, say, 700x20 tires (very skinny ones), that would be a very reasonable pressure.

To use the cartridge, it must be attached to an inflator, which allows you to control how much pressure you desire. The key issue is: since there is not a pressure gauge, the only way to know the right point is to know beforehand what the right pressure "feels like" with your current tire, and then trying to replicate that after you fix the tire, for example:


Thumb-checking the tire so that it is "hard enough";
Grabbing the seat or the handlebars and hitting the wheel against the floor so that it is "hard enough";
Riding the bike while looking at the bulge around the ground-contact area, so that it "looks right";
Riding the bike while hitting small irregularities on the ground, so that it "feels right".


(unfortunately the gauge from my floor pump broke, and I am becoming expert on "sensitive" tire inflation methods :o(

As a bottom line, if your tire is designed for 110 PSI max., that doesn't mean (at all!) that it will instantly explode as soon as it reaches anything beyond that pressure, because that is the maximum pressure recommended to BE RIDDEN. If you get, say, 130 PSI with the cartridge, you'll probably feel it is too much, so you can deflate it a bit before riding. In the end, between too hard and too soft, there is a lot of room for personal taste, specially if you just want to go on riding, after a flat.

Just as an example: I had (have?) a lot of friends who ride mountain bikes with knobby tires up to 80 PSI (it's crazy, I know), just because the bike "rides much better on asphalt". So far, no explosion happened (except one with a very low quality tire targeted at 40 PSI max... The girl literally hugged the road, but she was ok...)