The tool that goes everywhere with me is the Innovations Microflate Nano. It’s a simple chuck that fits on top of a threaded CO2 cartridge.
Purty, ain't it?
You screw it all the way on the cartridge, slip the nozzle over the tube’s valve, and then slightly unscrew the cartridge, releasing a gush of sweet, sweet, CO2 into the tube.
This thing has never failed me. I usually stick to the 16 gram cartridges - you can get 12 or 16, 16 gives you about 110 PSI in a 700x23 tire. I use it all the time for shorter MTB rides, for normal commuting and training rides close to home.
The upsides are that it's cheap and simple, probably impossible to break in normal use. It's tiny, leaving room in my tailpack for the other essentials that wouldn’t fit if I used one of the larger CO2 apparatti – a large Spin Doctor multitool with chain tool (more essential than you'd think); a Problem Solvers valve extender (lets you use a buddy’s 30mm stem tube in your Deep Vees) and a Surly Jethro Tool (for track nuts on the fixed gear, or to open beers).
The downsides are that threaded CO2 cartridges cost more, it takes two cartridges to fill up an MTB tire, and the cartridge will freeze to your hand during discharge if you aren’t careful – keep your glove on when inflating the tire, okay?
The other inflation tool that usually stays on my roadbike, or goes into the Camelback if I’m doing a really long MTB ride, is the Hurricane HPV Dual Mini Pump, sold by Performance and fine online retailers near you, providing you live in Seattle.
It's the backup system for long road rides, and on those multi-flat days when a tube and two CO2 cartridges just isn't enough. It looks really small but actually has a two or three-stage telescoping pump – you pull on the handle and increasingly small tubes keep coming out of the thing like snakes coming out of a snake circus clown car, until the plunger portion of the pump is nearly as long as an old school frame pump. You clip it onto the valve in the normal manner, put the tire on your lap, then start hammering away on the thing like Ron Jeremy at an audition. The telescoping pump allows you to get two or three times the amount of air that a shorter single stage mini pump would give you. This cuts your pumping time in half over the regular mini pump. I can get around a hundred PSI in a 700x23 tire in about 25-30 strokes, and I've filled a 29'er mountain bike tire with this without passing out or needing to take a nap mid-fill. A seven flat day taught me that a good pump is a real necessity. This is one I trust.
It's *much* better than any other mini-pump I’ve ever used.
The other upsides are that this pump is reliable, it's outlasted Bell, Serfas, Blackburn, and other Performance mini pumps I've tried - they all sucked while this one totally blows. It only costs about $12 and it comes with a nice plastic mounting bracket that attaches on the braze-ons. You just slip them on under your water bottle mount and attach the water bottle holders normally. -
The downside is your trendy but dumb friends may make fun of you for proudly sporting the Performance logo on your Fondriest or Calfee. But hey, nobody said "the best" would be the most expensive or the most glamorous. Maybe you can sticker it up with some Colnago decals off E-bay, if that makes you feel better about it.
The two other key elements you really need to have on hand and know how to use are tire irons and a patch kit. An extra tube is nice but on a multiple flat day, you don't want to get caught out. I prefer the old school style (patch + sandpaper + glue) because they seem to hold up better over the course of a season being ignored in my tailpack, while the Skabs and other one piece patches tend to have trouble adhering to the tube once they've been drenched in a soaking rainstorm. Just a reminder - you sand the hole until the surrounding rubber is roughed up, apply the glue, *let the glue mostly dry for a few minutes* then apply the patch. You might also want to consider making a steel core Serfas tire lever the one you carry in your tailpack, particularly in the winter. The regular plastic levers are a bit fragile in serious cold, and the last place you want to be is 5 miles from home, in the cold, sweaty as hell, on a bike with a very tight tire, that you can't seem to get off. The best pump or CO2 cartridge in the world won't do you a damn bit of good then. Y'know how some experiences make a strong impression on you? That one will.
Take my word on it.