How Much CO2?

One of the A riders in the club posted on the Yahoo group that he was making the move to CO2 cartridges, after many years of resisting them. That started online discussions that took two separate tracks.

12g threaded

Another member asked, “How many pounds of pressure does a 12 gram cartridge impart to a 700×23 tire? I use 16g cans and still have trouble getting home with the optimum 92-94 lbs onboard.”

The Internet is a wonderful thing. It doesn’t take long before answers start rolling in. Multiple answers.

“I’ve never checked the actual pressure,” answered a fast rider, “but my 23’s are quite firm after using a 12 gm cartridge. I just did a bit of research and it appears that you get about 100 psi in a 23mm tire from a 12 gm cartridge and about 125 from a 16 gm.”

But that doesn’t allow for individual differences. The fellow who posted that probably doesn’t weight more than 130 pounds soaking wet. The original poster followed up:

“Am I the only one who rides 25 mm tires? What did your research say about the pressures in the larger road tire?”

Cripes. We haven’t answered the cartridge size question yet, and now we’re introducing tire size variations? It’s gonna get confusing.

“I ride 25s too,” chimed in another member, “and am somewhat heaver than Steve so you probably will not be surprised to hear that I only roll with the 16s on the road bike.  However, I also put some Gatorskins on the wheels so I don’t get flats very often any longer [although I just jinxed it and am sure to get a flat on my next ride] so the extra cheese spent on the threaded 16 gram cartridges isn’t a big deal.  If you use less than 6 of these a year, it’s not a major expense.” But he also had a practical suggestion.

“Go buy a 12 gram and a 16 gram cartridge.  Let all of the air out of your rear tire, fill it up with the 12 gram cartridge, and go for a ride.  Repeat with the 16 gram.  Which did you like better?”

I imagined pffffft! sounds coming from garages all over the neighborhood as cyclists took him up on that idea.

16g unthreaded

Then, of course, there’s that complication you get with CO2:

“Bear in mind that CO2 bleeds out of a tire much faster than pumped air,” wrote the 130-pounder, “so if you fix the flat in the early part of a three-hour ride, you will find a lower pressure when you get home. This is why, after fixing a flat on the road with CO2, I always deflate the tire and refill it with a pump at home. However, unless it gets down in the low 80 lbs range, you shouldn’t have any problems short of a pinch flat if you hit a big pothole or rock.”

Okay, this is all good information. But one member had a great idea: Go right to the source. The Genuine Innovations website has a link to an inflation chart.

“Unfortunately there isn’t a measure for the 25mm tire,” said the guy who suggested experimenting. “But there is one for 23 and 28. You should be right in the middle. It looks like a 12gm will get you 90psi in the 23mm tire and 62psi in the 28mm tire or about 80psi in the 25mm. If you want a higher pressure, go with the 16.”

What was the second discussion track? Cost, of course.

The original poster wrote: “If you buy cartridges from a bike shop they can be pretty expensive. I just checked online and it appears that you can get them reasonably cheap if you get a bunch of them. For example you can get a box of 50 16 gram non-threaded cartidges for $50 including shipping. And different prices for different amounts. but 50 for $50 seems about the best.”

Another replied, “Buy a box of 12 gram cartridges at Walmart in the BB/paintball gun section. 15 for $7.97.”

“+1 on that recommendation,” said a third.  “I buy mine in bulk from a discount sporting goods store.  The only thing is that these do not have the threads to screw into some of the smaller nozzles.  I had to use it this weekend and a single Crossmark CO2 cartridge inflated my tire in one shot.”

Well, that was settled pretty quickly. Looks like a bunch of my club pals are headed for Wal-Mart to get their CO2. But one of the previous commenters signed off with some wise advice:

“Even though I’ve had good luck with cartridges, I still have a frame pump attached to my bike just in case Mr. Murphy is drafting.”




I’m Switching to CO2

So while we’re on the subject of flats, I have to tell you about a 180-degree change in my attitude toward pumps. This is apparently a topic of never-ending interest among bike noobs, because a previous post about pumps and CO2 cartridges is the all-time most popular post ever put up on this blog.

Road Morph

As most readers know, I adopted a frame-mounted mini pump — the Topeak Road Morph — three years ago as my preferred way to get the tires up to pressure after a flat. I had just fumbled and bumbled too many times with CO2 cartridges and decided I needed something more reliable. The Road Morph proved to be the answer. At least, for the several flats I had in the next year or so, I was able to get the tire pumped back up to the low end of its range, and ride home easily on it. At home, I could use my more powerful floor pump to top it off. The pump has bailed out fellow riders in group rides more than once, as they misfired their cartridges and needed something to fill their tires or be forced to call for a ride home. The picture at the top of this blog is of me and my friend David using the Road Morph to pump up one of his tires during a ride.

But during my three flats in two weeks run last month, I had help from riding partners in two of those cases. Each time, they suggested filling the tire with CO2 to get moving faster. As skeptical as I was, I agreed.

My friend David uses the little nozzle that attaches directly to the cartridge. Get it on the valve, turn it a bit, and pfffffft! — the tire fills without incident. Two weeks before, when I had my first flat, a fellow rider lent me his CO2 inflator. It’s the plastic housing that you slide the cartridge into, then use a small trigger to shoot the CO2 into the tire. I’ve got one of those, and I had consistently misfired the thing, wasting CO2, not filling the tire, and eventually switching to the pump. Maybe I’m older and wiser (no, not wiser, says my wife) but this time I filled it with no problem at all.

The weekend between those two incidents, I flatted while on a solo ride, which prompted the previous post about fixing them faster. This time I used the pump. The Road Morph is terrific for the first 60 pounds of pressure. Then you have to work harder. It’s got a built-in pressure gauge down by the valve, so you can see how well you’re doing. By the time you get to 90 pounds, you’re pushing with all your strength and the pump is barely moving. I know I’ve gotten tires up to 100 pounds in the past with the Road Morph, but it’s a struggle. And given how easily the CO2 cartridges work when used correctly, I decided to change my ways.

Inflator and cartridge.

So now I’ve got my inflator with the trigger and two cartridges in the seat bag. But in true belt-and-suspenders style, I continue to keep the pump mounted to my frame. One way or another, I’m going to leave the scene of future flats with properly inflated tires.

What the Hey, I Added a Pump

Guest poster Don Blount makes what, for him, is a major concession.

I finally settled my personal pump vs CO2 debate.

When I first began riding, I went weeks without carrying anything – a pump, CO2, patches or tire levers. I was just lucky, because I didn’t have a flat during this period. I was dumb too. Now, I wouldn’t go anywhere without the basic tire changing implements.

Shortly after I had those tools, I flatted on a hot summer day. It took me more than 20 minutes to change that flat and get the bike rolling again. On that hot summer day, it seemed like forever.

I have had more than my share of flats since and have become proficient at changing them although I’m not as fast as this guy. It takes me about 10 minutes total time to get the flat changed and the bike rolling again. And note that the guy in the video changes the flat in no time but doesn’t look for the cause of the flat.

CO2 is one of the things that I use when changing flats. I like the speed and also the convenience in part because my many of weekday rides come before work when a flat not only cuts my ride short but also shortens my preparation time to get ready for work or another appointment. The faster I change the tire the more likely I am to get to my next stop on time.

Mishaps are of course nerve wracking.

Last October while my wife was out of town I was returning home from a ride. My plan was get a quick shower and change and pick up my then three-year-old daughter at her preschool. I was on schedule, but about a mile from home I flatted.

Hurricane HPV Dual Mini (this is the old pump)

I changed the tube, took out a CO2 cartridge, pushed the nozzle and pssssst, it was a dud. I had two more cartridges. I kept getting a bubble in the tube and bam! overinflated the tube causing it to pop. I had one more tube and one more cartridge. No pump. I had stopped carrying a pump thinking that the CO2 would replace it. Quite frankly I never liked the pump, the few times I had used it, it didn’t work well, in addition to being bulky I wasn’t able to get much air in the tire.

I was already thinking of how long it would take me to push my bike to my daughter’s school in full riding gear.

I got the second tube inflated, mushy but rideable and picked my daughter up on time.

Common sense should’ve told me to look for another pump. Instead I worked on becoming more proficient at using CO2.

For that matter I didn’t think much about adding a pump until a few months ago when I came across that photo of George Hincapie’s training bike and saw that he was carrying a pump.

If one of the world’s top racers had one on his bike, why wouldn’t a recreational roadie? I’m not racing, I’m not hammering and a few extra grams of weight isn’t going to cost me anything.

Blackburn Airstik 2Stage (this is the new pump)

I decided that I should carry a pump, but it had to be the right one – small, affordable and effective. I ended up buying a Blackburn AirStik 2Stage, the one Hincapie was carrying. It is small enough to fit in a jersey pocket, although I mounted it on my bike. And it can get a tire up to riding pressure in about 200 pumps, that was about 90-100 psi. (I tested it.) And the $22 cost, including shipping, was within my budget.

I still carry CO2 and intend to use it as my primary method of inflating flats, especially when I’m short on time. However, having a pump on board provides me with a backup if there is a problem or as an alternative inflation method for those times when I have time.

SPECS Hurricane Blackburn
Length 267 mm 170 mm
MAX. PSI 100 160
Weight 185 g 84g

Don advises that the Maximum PSI figure for the Blackburn may be a little misleading. It can pump 160 psi “only if you’re Hercules,” he says.

CO2 vs. Pump – Hincapie Chooses a Pump

Sharp-eyed guest poster Don Blount came across an interesting tidbit, and offers it up for discussion:

This image was on the VeloNews Web site in a photo gallery of George Hincapie’s new training bike. In this closeup you can see what appears to be a Blackburn air pump attached to the frame beneath the water bottle cage.

After investigating further it appears to be the Blackburn Air Stik 2stage. (If my guess is off, please correct.) According to the Blackburn Web site, the Air Stik 2stage pumps to a maximum 160 psi. That would certainly take care of my tires.

Now if one of the top racing pros carries an air pump on his training bike, why wouldn’t everyone else? Given that, I’m sticking with CO2, at least until I run out of cartridges.

CO2 or a pump? — It never ends

I was chatting with a friend the other day who’s just getting into biking. He was telling me of his experience with his first flat. No pump, no CO2. He had a patch kit in his seatbag, but realized it was worthless unless he could fill his tire with air, so he wound up walking the bike home — three miles.


Do you prefer these?

“I saw these canisters of CO2 at the bike store,” he said. “Are they any good?”

Here we go again — the endless debate between CO2 and a pump.

Well, I told him, each has its advantages. CO2 takes up just a little space in your seatbag, and you don’t have to carry a pump. Just attach the inflator, stick it on the valve, and whoosh! you’re back in business. He liked that. He thought he’d try it.

But wait a minute, I said. There’s a problem with CO2, too. Sometimes, you misfire it and waste all the gas in the canister. Then, you can find yourself in the same predicament you were in last week.


Or this?

I told him of a recent A ride from our club, where a guy flatted along a major highway. One of the other guys had several CO2 cartridges — and managed to depressurize all of them. Without inflating the tire. Luckily, another rider in the group carried a pump, and stood by to watch the antics — then stepped in and saved the day.

“It took me probably 10 minutes to pump up a tire to 70 psi,” said guest poster Don Blount in an email awhile ago. “That’s longer than it took to change the tube.”

I’ve been there. It doesn’t take me that long to pump a tire up to 70, or even 90 psi. But those last 10 pounds to 100, to make it roadworthy again — I should be doing some strength work at the gym.

But Don also said he blew a tube with one cartridge, and when he went to use another one on another tube — it was a dud. He thinks he might just suck it up and go back to the frame pump.

At least that’ll get the tire inflated. With a cartridge — I’m guessing 50-50 odds.

My friend went back to the bike store and got a frame pump.