I'd add being very precise with your flat repair technique to the list. If you've left a thorn or shard of glass in your tire, you'll get another flat shortly and may not have enough CO2 cartridges to get you home. If you have pinched your inner tube under the tire bead CO2 inflates your tire so quickly that it'll blow out before you can catch your mistake. CO2 doesn't give second chances.

Carbon dioxide will seep through the inner tube so you will have to pump it up again with normal air again anyway.

I've never used CO2 and never had a desire to. I used to use Zefal HPX pumps, but have since switched to Giyo mini pumps that I have found to be excellent, store on the bike discreetly, and have a head that fits on and comes off presta valves without any issues.

The Giyos (I think we have five or six of them) inflate narrow tyres to the pressure I want, and do so without too much effort because of their narrow bore. About 120 rapid strokes, and I am in the 90-95psi ballpark for my 23C tyres.

I get the Giyo from Torpedo7 in New Zealand. It is probably a rebadged version of another brand available in North America.

Time: ~ 2 minutes to pump up my tire with a minipump.

I changed out a tire this morning and inflated it with a Lezyne Road Drive minipump (93 gm actual) timing how long it took. Pumping steadily as I normally would, changing position a couple of times and pausing to pinch the tire, it took 2 minutes 5 sec. I checked the pressure with my floor pump and it was 95 psi. I run 90/100 f/r.

For me, the time saved doesn't justify CO2. A physical malady inhibiting my ability to reasonably use a minipump certainly could.

I never timed myself but, back when I used an HPX, I doubt I could get up to 95 psi in 2 minutes. Four or five minutes maybe. I used to have to brace my hand against a tree or utility pole or something to get the last few psi into the tire.

My current weapon of choice is a Road Morph. The only functional thing I don't like about it is it's too short and I have to bend over more than I like. That and I think they're ugly but I use great big bags on the back of my recumbents so it doesn't show.

I've been using this for abut 3 seasons. Haven't had many flats but when I did it worked as advertised both as a CO2 and manual pump.

I also use a pump + C02. The two most highly recommended are the Road Morph and the Lyzene that two folks here showed. My C02 is kept in my saddle bag. With a few tests I learned that if I pump 20pumps from my Lyzene into my 25c tire I can then top it off with a 16gr C02 cartridge and I'm right at 110 lb. The weight of the Lyzene is so small that unless you are racing it simply has no downside. C02 is really helpful to keep you from holding everyone else up and the pump ensures you won't ever be embarrassed by running out of C02. I've used all my C02 cartridges helping OTHER people. One person who fails to actually repair their tube and boom! You've used up 2 cartridges.
BTW....C02 will diffuse through the inner tube much more quickly than regular air does so whenever you use it you need to bleed it out and pump "for real" after you get home.

Just no place to mount them on most current frames.

That never bothered me. I always topped off my tires with a floor pump before every ride so whatever is lost between rides was of no consequence.

I carry a C02 cart, but since I started using tire liners I don't get flats. 4000 miles on this set of Continental GP's and zero flats. Same with the last set of tires. The only flat I've had in the last two years is when I bought my new Ti bike and I got a flat before I could put in the liners.

NO2 is more amusing..

http://www.modernbike.com/itemgroup....Fcqj4Aod8hoA6g

Might I suggest a Red Zepplin inflator. It screws on to the valve. The cartridge screws into it and it has a valve to control inflation. That pretty much takes care of the potential screw ups. Put on0e layer of 200 mph tape around the cartridges to insulate your fingers and prevent noise as they bang around in your bag. 1 16 oz cart will do a road tire nicely. You may need 2 for a high volume MTB doughnut.

I used to carry a frame pump, but now I carry two or three co2 cartridges and this inflator. I don't think I'm saving weight, but I'm too cranky of an old man to sit there and hand pump my tires to 110+ lbs anymore.

http://www.amazon.com/Innovations-Ai...d_sim_sg_cy_29

I've been on the road where other guys brought out their co2 inflators, and failed miserably. I brought out this one and saved the day. It's never failed to work for me.

I carry two cartridges with a GI chuck. So far, I've never needed more than one cartridge at any time.

What happens if you get a flat, repair it with CO2, then get another flat, but you only have one spare tube? How are you going to find the leak, if it's small, without a pump, with just that one spare?

If you have to carry a second spare, just so you can save weight with more CO2, then what's the point of CO2?

I carry CO2 for my road bike, a mini-pump, and one spare tube plus a patch kit. (On my fixie, I carry a more powerful, yet still small, Lyzene pump attached to the frame, a spare tube and a patch kit, and no CO2.)

Never thought of the tape thing. That's a good idea.

I believe CO2 kool-aid is soda pop :)

I use frame pumps on 4 out of 5 of my bikes and a mini pump on the 5th because it is a Softride and I can't fit a frame pump on it. I do have CO2 and carry it only for races (triathlon and duathlon) but I have never had to use it (there, now I just jinxed myself).

These new combination CO2 pumps have a nice appeal. Currently I carry a CO2 inflator and a Topek Road Morph G pump. My thought on carrying a single inflator is the failure situation. What if the device fails? It is always nice to have a backup to get you home.

The flat gods have spoken!
 

The flat gods spoke to me today, and this is what they said:

"Thou shallt carry two independent means of inflating a tube."

OK, they didn't use those words, instead they caused my Road Morph G to explode when I was fixing a flat. That is, it morphed from a bicycle pump into this:

http://bikeforums.net/attachment.php...hmentid=320813

Luckily it didn't explode until it got to 90 psi, so I was OK.

Apparently the plastic threads into which the main cylinder screws are somewhat stripped. I can screw it back in, but even with a little torque, it "breaks through."

I've said before that I have a love/hate thing with the Road Morph. When it works, it's great, but this is the third or fourth time it has failed. And the failures have been due to poor design (pins falling out, things rusting, plastic threads). I'm through with Topeak.

I like the hybrid pump/inflators, but they don't satisfy the flat gods' dictum.

The Road Morph became obsolete when the Lezyne line was introduced.
My Road Morph has been sitting on a shelf in the garage since I went Lezyne.

I'm considering this for the pump.
I like the screw-on idea. Is much gas released when you unscrew it?

I have been using the Genuine Innovations SecondWind Road Air 2 Pump for several years now and many times works great and pumping by hand to 100psi is not hard at all. Put the CO2 cartridge on the handle pump side and it gives you a good grip to hold. Best of both worlds in one great price right now from Performance Bike also.

I ordered the Ultraflate plus today (thanks, PlumberRoy). It seems like 12 oz unthreaded cartridges will be the cheapest, and be perfect for my 700x23 tires. If I want to use threaded cartridges, I won't need to take the outer shell.

Tomorrow I will order this and these unless someone has a reason to reconsider.

Thanks for the help.

The Lezyne "HV"(High Volume) models are for mtn tires.
The "HP"(High Pressure) models are for road tires.
You want the "HP" version of that pump for a 700x23 tire.

Ah, thanks, I'm glad you caught that. I will get this one.

If you're using Presta valves (and you probably are) very little escapes. The adjustment valve can be closed off so that the cartridge is sealed again but that won't hold pressure forever.