Flat tires, they happen to everyone eventually. I have been pretty fortunate in that department and haven't had to deal with many (although I'll have plenty now that I said that) and all of them have occurred while mountain biking. Having just gotten into road riding last year my thought was if I can just avoid the pot holes (in Michigan that's easier said than done) and random foreign objects in the bike lane I should be ok.
Then one day it finally happened. I was on a perfectly innocent bike ride on a route I've taken many times before. I decided to take a detour to check out a small lake I had never ridden by. After enjoying the lake for a bit I was off to begin the second half of my bike ride, about 15 miles from home. It was then that I heard a hissing noise and figured I either had a really mad snake tangled up in my drivetrain or a soon to be flat tire. Fortunately it was the latter, but I was still going to have to repair the tire. A random screw (that wasn't even sharp) had punctured the tire. It must have been hit at just the right angle.
Fortunately on this ride I did grab a saddle bag on the way out the door, but I distinctly remember almost leaving it at home with the thought "I haven't needed anything out of this thing yet, why waste time attaching it to my bike when I could get out and ride sooner". It seemed other than the flat, luck was on my side since not only did I bring my saddle bag, but in it was a spare tube, tire levers and the PDW Shiny Object CO2 inflater.
I've had other CO2 inflaters in the past. Most of them were made of plastic and other cheap components, like a rubber band to hold the CO2 cartridge in place. However, the build of the Shiny Object (we'll call it the SO to save time) is anything but cheap. The construction is solid and other than O-rings, appears to be made entirely out of metal. When you pick it up, it feels like a device you can depend on. There is no cheap rubber band to lose either. The SO uses standard threaded CO2 cartridges and they are held firmly in place once tightened down.
Now, you know the cautionary tale all bike shops and online blogs tell you about your emergency equipment and how you should know how to use it? They say to be sure that you try this equipment out in a non-emergency situation, like in your garage or basement, before you actually need it to get you home. Well, as I'm sure you've guessed, I didn't do that.
Luckily for me the SO is pretty self explanatory. After changing the tube and wasting one cartridge due to over inflating the tire and pushing the bead over the rim, the second cartridge filled the tire easily to the proper firmness (I would say PSI, but I didn't have a gauge, I just used the two finger squeeze test, very scientific). Once filled, I hurried back home since I know CO2 won't keep your tire inflated for as long as air from a traditional tire pump (something about the CO2 molecules being small enough to seep through the semi-porous tube and tire rubber material, but I'm not a chemical engineer, so ask google if you want a more indepth explanation).
The SO has a very well machined valve with smooth CW/CCW (with arrows to help guide you when controlling the valve) action by way of a nice knurled knob that makes precisely controlling the release of CO2 easy. It is easy to release and stop the flow so you can put in a bit at a time until the tire feels just right.
Some CO2 inflaters are a one use setup where there is no valve, so you better make sure it seats on the tube's valve stem and stays there or you'll need that spare cartridge you brought. With the PDW SO, I was able to keep the cartridge connected since I didn't use all of it to inflate the tire (the second time). I did test it to see if there was still CO2 in it a few days later and there was a fair amount in there, maybe even enough for another road tire. It didn't seem like any had leaked out in prior days.
At this point I can tell you I am a fan of this CO2 inflater. So much so that I bought a second one to keep in my other saddle bag so I don't forget it if switching bags between bikes. You can usually find this on Amazon at the cost of around $15, well worth it for the piece of mind it provides and cheaper than many other alternatives.
They do have another configuration that comes with a leather sleeve to put around the cartridge in case you don't want cold fingers while releasing the CO2. I find that it doesn't get all that cold and gloves were plenty for me to keep my fingers from freezing. Now if you were filling a MTB tire and needed a couple cartridges in a row to fill the tire (or you're the kind of person that likes finely sewn leather goods), it might be worthwhile. Winter is another time where the sleeve may be useful, but again, if you've got gloves or something else to hold the cartridge with (like the tube with a hole in it), you should be fine without the leather sleeve. Use the money you save to buy a few spare tubes.
I'm sure there are plenty of other CO2 inflaters out there that will work just fine, but I will be using this one for a long time to come. Judging by the look and feel of how it's built it will be a permanent part of my flat tire emergency kit for many years to come.
Be sure to check out the Portland Design Works Shiny Object (big name, small device) and other great products from PDW at your local bike shop (preferably), Amazon or at their link below: