C02 cartridges are only for "temporary" air ... WHO KNEW?!!!!

[Jiffer]

I have had a lot of back tire flats, all in a row lately. I took my bike in to get new tires and asked them to check out my wheels to make sure there's nothing about them causing my flats. I asked the LBS guy tips on using the C02 cartridge, because my dh had mentioned you have to be careful not to ruin your tire valve when you pull them off and I was worried that was why my tires might have gone flat. I then told him my dh had just given me a reminder lesson on how to use the C02 by having me use it on my bike. We let the air out and I filled it with the C02. The next morning, my tire was flat.

The bell went off in LBS guy's head and he explains to me that C02 air is only temporary air. It goes away after around 18 hours. It's to get you home, but you have to refill with your tire pump before your next ride. (He recommends doing it as soon as you get home. Let what's left of the C02 air out and pump regular air in. That way, the next time you go to ride your bike, if your tire is flat, you now it's actually flat and not just the C02 disappearing.)

Anyways, this was news to ME!!! Why hadn't my very experienced cyclist husband told me this?!!! And then I got to thinking that he surely must have, like a year ago when he taught me how to change a tire, and I had just forgotten.

So, he calls me from Utah today, where he had just finished a marathon. After he told me how great he did, I told him I learned something today. And then, as if I'm teaching him something new, I say, "C02 is only temporary air. You have to refill with your tire pump before your next ride." There was silence. And then he said, "Really?"

He didn't know!!! I couldn't believe this!!! This man man came in 4th at Ride the Bear with like 13,000 feet of climbing and thousands of people racing it. He's been a serious cyclist for several years now and has changed lots of flats out on the road using C02 and this man did not know this extremely important piece of information! I told him, if he thought back, it would probably explain some of his, so called, flats and he said I was probably right.

Wow. I actually taught HIM something today. ;)

[DigUpHerBones07]

Good for you! I love it when I teach my husband something. It makes me feel cool. Also, thanks for the heads up, I have been debating on getting a CO2 cartridge or a regular bike pump, I guess now I would need both! Thanks!!!

[kfergos]

Hmm, thanks for the interesting info. That kind of makes sense; maybe pure CO2 escapes through the pores in your tubes more easily than the mixture of gases in the air? Although air is mostly nitrogen, if I recall correctly, and that's N2. Wouldn't that molecule be smaller even than CO2 and thus even more prone to seep out? That makes me wonder what the composition (%) of air in our tubes is, and if over time it ends up with different gas ratios than the air around us. Chemistry nerds on TE, help!

Anyway I'm not a CO2 cartridge fan anyway. Every time I try to use one, it blows up or doesn't work or something. I'm going back to a good ol' hand pump as soon as I get my new bike.

[Mr. Bloom]

I just learned something too! I bet Silver didn't even know this!

[kermit]

I was actually told that Co2 is heavier than air. Thats why is doesn't last. I hate using them as well but its a necessary evil. Flats suck more.

[Veronica]

I don't think this is true.

Serious dirt bike racers use compressed CO2.

I think this needs a little research before being accepted as valid. Just ' cause the LBS guy says so, doesn't make it true.

Veronica

[Aggie_Ama]

My personal research is this is false. I have changed plenty of flats using CO2 and not had another flat on the tire for months. I do air the tire with a floor pump before the next ride so maybe that is why but I haven't had recurring flats on the tire that had CO2 on the road. My husband and the LBS pounded into my head on a skinny road tire air it up before each ride unless you are a fan of leaving the bike open for a pinch flat. I have never had a CO2 filled tire be low in enough to call it flat 18 hours though, 10-20lbs pressure yes but I have seen this on regular old air too.

[VeloVT]

This is just not true. I usually only inflate every 2-3 rides (unless I've done a particularly long ride). I have on numerous occasions fixed a flat with CO2 and had plenty of pressure in the tire for another ride or two (I like to keep them pretty hard too).

Could it be that you are underinflating? If you are not careful with CO2, you can lose a fair amount of it trying to inflate the tire... if you are underinflated to begin with, you are more likely to flat. Also for some reason tires seem to lose pressure faster when they start from a low pressure (not sure why, but it seems to happen).

I love my CO2 pump :).

[batsheva]

CO2 is smaller molecule than N2 - (the main component of air) so the CO2 seeps through the rubber of the tube/tire faster than nitrogen, and so the tire loses pressure faster-- they don't have air in the little cartridges because nitrogen molecules are much less compressible than CO2 so you would need a much bigger cannister if they were filled with regular air..

[Eden]

I'm pretty sure this is true. If I fix a flat with co2 I always have to pump the tire up the next day. I wouldn't say they get totally flat, but pretty squishy. Still I love having cartridges over a hand pump on the road. I still carry a really small pump for emergencies, but there's nothing like changing a flat in 40 degree rain and having to pump and pump and pump with a little hand pump just to get 70 lbs of pressure. Blech - co2 is so much quicker.

Even plain old air leaks out slowly, if I let my tires go a week without pumping them up they'll go from 100 lbs to 80.. its just not as much or as noticeable as the loss with co2.

[OakLeaf]

Well I was skeptical when I first read this, but after I thought about it...

Race cars fill their tires with nitrogen... NOT because it doesn't heat up the same as room air as a lot of people believe... but because it doesn't escape the tires as quickly as room air.

According to a trade organization (http://www.getnitrogen.org/why/index.php) (fwiw), oxygen escapes through tires 3-4 times as fast as nitrogen. It doesn't give statistics for CO2 (which would have to be somewhat slower than oxygen), but it does say that nitrogen is the largest molecule in room air.

Bottom line is, it's a bigger deal for a car, since you air your bicycle and motorcycle tires before every ride anyhow, but you probably don't check your car tires daily. But yeah, I suppose now that I've read this, if I have a flat early on a long ride, I'd probably borrow someone's air pump within a few hours.

[SouthernBelle]

The drastic temperature changes the co2 goes through may affect all this too.

Just a thought,

[Fujichants]

I have to agree that this is true as well, and BF agrees. Whenever we had flats, we would fill up with CO2 and the next day the tire would be soft and have less air in it. CO2 is perfect to get you home.

Anyways, I always always always pump my tires before a ride. Personally I just feel as if i'm missing something if I don't.

[Aggie_Ama]

I always pump before my rides so the CO2 issue is pretty much null for me which may be why I say rubbish to it but I still haven't seen a true flat overnight with CO2.

Why pump before every ride? It is kind like how as a kid our parents make us brush every night, it is good for you yes but it also becomes habit. It just makes sense to check with a tire pressure valve every ride so I don't have to deal with pinch flat which pisses me off more than any other flat because it is so easily avoided. I cannot even count the number of times my tire feels okay to the touch but I put the pressure valve on it and it is only 80-90 PSI. Also I get so scatter brained some days I wouldn't remember if I did put more air last ride, two rides, last year. LOL. My 2 cents threadjack. :)

[Grog]

I have noticed that CO2 escapes a lot faster than regular air out of my tubes. It's not constant though and I suspect this may have something to do with the tubes as well (I have a batch of light racing tubes that seem to be leaking faster than my heavier tubes but maybe it's skewed perception).

I always pump up my road tires before rides anyway. If I've inflated it with CO2 the day before and it's particularly low when I start pumping, I empty it almost entirely and start again with "fresh air." :D

[maillotpois]

I think this needs a little research before being accepted as valid. Just ' cause the LBS guy says so, doesn't make it true.

Veronica

I agree. I have never noticed a CO2 filled tire needing to be re-filled more quickly. Perhaps it was not completely filled?



I must again post from Sheldon Brown's alter ego:




CO2 is heavier than air, you will make your bike heavy and slow if you
use it. Helium is lighter, the only way to go if you want speed and
safety.

If you are willing to live dangerously, Hydrogen is lighter and cheaper
than Helium, but don't smoke while riding your bike if you use
Hydrogen...

[kie_fujo]

the same thing has happened to my husband and myself. i asked my lbs about it the first time and they said that it must have been a fluke. then it happened to my husband as well. i believe it based on my experience. and both times they were completely full. once i refilled with my floor pump they held air just fine. but have never had co2 hold.

[sbctwin]

Before I knew better, I didn't always pump my "road" tires before every ride. On my mtn bike (now my commuter bike), I never pumped everytime I rode. I felt the tire and if the tire felt 'squishy' I would pump it up. But, on a group ride, on my road bike, I had a flat. The group leader that helped me fix the flat told me that as soon as I got home, I should pump up my tire. He said that the CO2 air didn't hold the air the same as my pumped air. Sure enough, I got home OK, but the next morning, my road tire felt really squishy, so I pump it up, fearing I would have another flat the next time I checked. My pumped tire remained good and by the next weekend, when I pumped up the tires for another long ride, my tires needed pumping, but not as much as it did the day after my CO2 fill. On my mtn bike (now commuter bike), I have had lots of flats this summer. My CO2 would fill it for me till I could get the tire fixed, but I would never feel like I was 'safe' until I actually put pumped air in the tire. I think the CO2's are good for the emergency fix, but not good for the long haul and if I have access to a regular pump, I will pump my tires for good measure.

[Mr. SR500]

CO2 works great! I used cylinders whenever needed and simply top off with a regular pump before every ride. I've not found any problems with tires loosing more air when filled with CO2, however some tubes leak more then others. I've had some I rarely had to add air, and other that would lose 10 psi in a day.

[Bluetree]

I usually dont have flat or squishy tires after using a CO2 cartridge, but I pump up the tires with a floor pump before every ride anyway.

If the tire does go flat after use on a ride, is it possible that something embedded in the tire is causing it, instead of the CO2? After all, the only reason to use one during a ride is if something is wrong with your tire and tube. Even if the tube is replaced, the problem still persists if something too small to be seen remains in your tire.

I had that happen once. After a succession of flats on one ride, close inspection at home revealed a tiny, tiny shard of a staple embedded in the tire.

[Crankin]

I always pump my tires before every ride, but, neither my husband or I have had issues with CO2 cartridges. I've only had flats 3 times in 8 years; one, where the tire kept going flat was because the tire had actually been cut.
I think this is what my grandmother called a "bubbie-meiser."

[OakLeaf]

Ah, more info here:

http://www.ornl.gov/~webworks/cppr/y2001/pres/117378.pdf

According to that (discussion of separation of gases by a permeable membrane - effectively similar to permeation of molecules through an inner tube), CO2 molecules actually have a larger effective hard sphere diameter than N2 molecules - 3.99 Angstroms for CO2 vs. 3.68 for N2.

So there goes that theory :rolleyes:

[smilingcat]

whew!!! Glad some one looked it up about the effective size of the two molecules. Carbon, nitrogen and oxygen are on the second row of the periodic table, with carbon in group IV followed by Nitrogen and finally by Oxygen. So when someone said CO2 is smaller than N2 :confused: huh?

Now about the permeability, just because something has an effectively larger diameter doesn't make it less permeable. Things that can affect is the Van-der-Waal force (something that poped up first in my head) and I'm sure there are others. but this can create drag on a molecule as it tries to permeate across a membrane.

I dunno whether CO2 will go flat faster than N2 filled tire. CO2 has a molar weight of 12+16+16=44 while nitrogen is 28. assuming both act as an ideal gas up to 100psi (PV=nRT law)... how much more does CO2 filled tire weigh than with N2?? if someone can figure out what n, number of moles to fill up a tire, then we would know the difference in weight. my P-Chem book is burried somwhere in the garage. And I'm in no mood to go look up the conversion factors and the value of ideal gas constant R...

Anyway, not sure which would leak faster. And that's my answer. Answer from your LBS sounds fishy.

smilingcat

[Jiffer]

I can't believe what a controversial thread I started! I told my husband not to feel too bad that he didn't know about the C02, because it's obviously not known by many and, in fact, is debated as truth by many. He says it makes perfect sense, though. And he said this explains why he sees tires being filled with pumps at the Tour de France. He could never figure out why they wouldn't just use an air compressor, which would be so much quicker.

We, too, fill our tires before every ride. And this would explain why dh never realized the C02 had leaked so much. He just pumped it no matter what. I agree that different tubes, tires and the weather may account for the C02 leaking faster or slower. I think the "18 hour" thing the LBS guy said was just a number he threw out to say you can ride quite a while, but it won't last forever. He wasn't being specific.

[Running Mommy]

our room mate works for a welding supply shop, so he knows a bit about gasses. co2- bigger.
Now helium- smaller, which is why it escapes balloons so quickly..
ya learn something new every day

[OakLeaf]

And he said this explains why he sees tires being filled with pumps at the Tour de France. He could never figure out why they wouldn't just use an air compressor, which would be so much quicker.

Um, an "air compressor" (like you have in your garage) compresses and delivers AIR. They could use pre-filled nitrogen cylinders... but why?

In high-level pro races they just swap wheels... so how long it takes to fix the flat is pretty much irrelevant.

I think the reason they use pumps in that context is control. You know how you fill a great big auto or motorcycle tire from a compressor - go over by a couple-three pounds and then let the air out with the valve in your gauge, right? Leaving the compressor on a skinny road bicycle tire for that extra second or even half-second could be enough to blow it clear off the rim. (BTDT at gas station compressors when I was a kid :rolleyes:) By the time you check and adjust the pressure several times, it's just as quick to pump a road bike tire by hand - with a decent floor pump it only takes 25-30 strokes to go from 0 to 120 (it seems like... I'll count them next time!)

[tulip]

Interesting news, y'all are serious investigators on this stuff! I've never used a CO2 cartridge. They did not exist for cyclists when I started riding in the 80s, so I've always carried a pump with me. My Road Morph gets me up to 100 PSI without any problems. CO2 cartridges can fail and people use them incorrectly, and if you don't have a pump, you're plum outta luck. Also, what do you do with the spent cartridges--just throw them away? That seems like such a waste somehow.

So even if you use CO2 cartridges, you might still want to have a pump for backup.

[Mistie]

N2 is a smaller molecule (2 atoms of N) than CO2 (1 atom of C and 2 of O). However, because our atmosphere is 78% N2, the N2 would escape more slowly because of the principle of diffusion. Thus, CO2 would escape quickly because there is less than 1% CO2 in the atmosphere and to reach equlibrium, the CO2 would have to move OUT of the tire. In the case of N2, equilbrium is reached quicker because there is more N2 in the outside of the tire (atmosphere). Sorry for the chemistry lesson, I have a BS in it.

[kfergos]

Mistie - How 'bout the other interactions between the rubber of tires (the stuff smilingcat brought up) and CO2 vs. N2? Surely equilibrium isn't the only thing that determines how quickly you lose pressure in a tire?

[pardes]

I was actually told that Co2 is heavier than air. Thats why is doesn't last. I hate using them as well but its a necessary evil. Flats suck more.

Air is a combination of about 80% nitrogen and 20% oxygen. Carbon dioxide is actually more dense than air.

If you mix vinegar and baking soda together in a container with a lighted candle, the candle will go out since the carbon dioxide produced pushes the air (lighter) up and the carbon dioxide (heavier) stays in the bottom and extinguishes the flame.

[Triskeliongirl]

I like Mistie's explanation the best, but I am sure we can't rule out additional factors as well.

I do agree with the fundamental observation that a C02 filled tube deflates faster than an air filled one. I too always considered C02 as temporary air, and after using it as soon as I get home I always remove all the C02 and replace it with air (not just top off, but deflate and reinflate).

[SadieKate]

Interesting news, y'all are serious investigators on this stuff! I've never used a CO2 cartridge. They did not exist for cyclists when I started riding in the 80s, so I've always carried a pump with me. My Road Morph gets me up to 100 PSI without any problems. CO2 cartridges can fail and people use them incorrectly, and if you don't have a pump, you're plum outta luck. Also, what do you do with the spent cartridges--just throw them away? That seems like such a waste somehow.

So even if you use CO2 cartridges, you might still want to have a pump for backup.Can't disagree with a word you've said. Pumps provided unlimited air and don't fill up the overstressed landfills.

[Bluetree]

Also, what do you do with the spent cartridges--just throw them away? That seems like such a waste somehow.

Several of my LBSs recycle old tubes and spent cartridges. I just throw them in a box until my next visit, then drop them off.

[kfergos]

A lot of the cartridges are straight steel or aluminum, which is recyclable in most places, too. Even so it does seem like a waste compared to free air and one device to put the air in your tires.

[Crankin]

Some of us have bikes that are too small to fit a pump on. I had a very nice Road Morph pump on my Trek, but even that took a lot of work to figure out a place where it would fit. I absolutely can't put a pump on my Kuota. It's not just the size, but the shape of some parts of the bike where you would usually put a pump.
I have the metal cartridges.

[OakLeaf]

The Topeak Micro Rocket (http://www.topeak.com/products/Mini-Pumps/MicroRocketAL) series - I can't think of a bike that it wouldn't fit on. Plenty of room between my left crankarm and frame. And if it really won't fit on your frame, it'll go in a jersey pocket or seat pack.

Not the quickest way to air a tire. Not very polite on a group ride unless you make it very clear that you don't want anyone to either wait or lend you their CO2. But it definitely is good for enough pressure that I'm comfortable finishing out a ride.

[SadieKate]

I haven't met a bike bottle cage yet that can't handle a Barbieri (http://www.glorycycles.com/bacatwopu.html) and it pumps pretty well to high pressure.

[JaneE]

I managed to post this note in the wrong thread the other day...no computer genius here! :o

I'm a recent convert to CO2 usage on the road. I have observed that my CO2-inflated tires do not hold pressure as long as pumped tires. I thought it was just me, that I'd done something wrong, but obviously others have observed the same thing.

I resisted using a CO2 inflator and always carried a Road Morph pump with me (which is a very nice pump, imo). Unfortunately, the RM does not fit on my new Ruby and I've been forced to carry a mini-pump (a Blackburn Airstik: http://www.dealhaven.com/storefrontprofiles/processfeed.aspx?sfid=134849&i=237850988&mpid=9720&dfid=1 ). It works but it's a MUCH greater pain the in rear. So, I pulled the CO2 inflator out of moth balls and now carry it and a few cartridges on my bike as well as the mini pump for back-up. It's a compromise: neither one by themselves is an ideal solution.

And +1 that those empty CO2 canisters are recycleable. Any empties I might have after a ride are put right into our recycle bin for weekly pick up and we've had no complaints so far.

[Crankin]

I guess I'm not willing to put up with the time and pain of the other pumps. The Road Morph worked so well (though I only had to use it once). I am weak enough as it is and scared to death of anything mechanical. Although that one you posted SadieKate, looks promising.
I've avoided the issue by hardly ever riding alone. I have the cartridges and when I ride alone, it's usually not that far from home and it's in places where it's quite likely other cyclists will be by if I am really in a fix. I know this is stupid, but I spent quit a bit of time a couple of years ago being paralyzed by the fear of a flat. This seemed to be a good compromise. So, while I will do a 25 mile ride alone, I won't go out for 50 miles alone...