CO2 Inflators
 

Can anyone tell me what size CO2 cartridges to use with a 700x25c tires. 12gr or 16gr. The recomended tire pressure is 120lbs. I know under inflated tires are bad to ride on. How much over inflated can you be without causing damage. I know I should invest in a gauge but when your on the road its just one more thing to pack.

str8shooter

I use 12g on my 700x23 but they are rated for the same pressure as yours (120psi). I don't carry a gauge with me either but from what I've been able to determine I get around 90 psi from a single cartridge. This may be less than perfect but it gets me back on the road quickly and I can use the cheap walmart CO2 cartridges.

Dan

I use 16 gram on 700-23's and that gets me to 120 psi + the amount that leaks because I'm not very mechanically gifted. For 25's, I'd go with 16, but you might not get to full inflation.

BTW, I've been told that once you get home after using a CO2 cartridge, you need to let all the CO2 out, and pump up the tire with air. Has anyone else heard of this?

I haven't heard of this, but I do know when I get home, I repump up the tires anyway, since I don't quite get the pressure I like to ride with when I use the one cartridge.

Koffee

P.S. I use the Walmart cartridges too. They are cheap, and I like 'em! :)

I use the 16g cartridges on my 23c and 25c tires. By gauge when I get home, they're at about 90-110 psi. As for the overinflation, a loose rule of thumb (it's years old, so it might be dated, but it works for me) is that the pressure listed on the sidewall is about 2/3 of the actual blowout pressure. I'm not sure that overinflation can cause damage, at least until you hit that critical pressure that causes the casing to burst. I routinely run my Michelin Carbon's up at 140-145 pounds (on the rear tire, anyway), and I've had no problems. Before you ask, I do like my ride kinda rough and fast. :-)


Grab some 16's from Wal-Mart, and away you go.

Are the cartridges from Walmart threaded?

no ... but you can buy a small CO2 pump that takes either threaded or untreaded cartridges.

-mark

Ok I may have to look into that. My current CO2 set up takes only the threaded cartridges.

I've never done this and I can't imagine what the harm would be in leaving it there, seeing as CO2 is present in room air, anyway.

Paul

what is the cost of the 16 gr cartridges at Wal-mart? If it is a big enough difference I will spend the $20 dollars it will cost me to buy a CO2 systems that takes both threaded and un threaded.

I can't remember how much exactly, but I think for something like a 25 pack, it's like 12 bucks. It's well worth the investment of a CO2 gun that takes both kinds of cartridges. I got 2 packs myself, and I paid about 25 bucks for the two boxes, and I have 50 cartridges I can spare, so I don't even have to worry about wasting precious moments pumping with those pathetic hand pumps again!

Koffee

I use either.. what ever I get at a good price.
But, when I inflate a tire I use my pump to fill the tire with air, low pressure, which is very easy to do, and then use the cartridge to bring it up to pressure.

Yeah I still keep my frame pump with me.. cause for one thing, say you get a blowout, and can't find the hole... you wanna waste co2 so you can find it? Also, I like to check my patch job with it... then I put it back in the tire, hit it with the Co2 and away I go.

I use 16g cartridges... the 12g ones don't get enough air in there for me to feel comfortable about not getting a pinch flat.

I've also heard that going 10% over isn't bad...and some people actually recommend it...

I gotta find cheaper cartridges though...the LBS wants $3 each, and I'm morally against shopping at walmart...

I use 12 grams, but I have the second wind co2 thingy so I give it a few pumps at low pressure and top it off with co2. Gets me home.

FWIW, I let out the co2 and pump it back up. I've heard that co2 leaks out of the tire faster than air, but I can't confirm this.

-murray

I do believe you're right about them leaking out quickly. My tire went flat so quickly the last time I inflated with CO2, I thought I had another flat. Now that I've inflated with the pump, I can see that I do not have a flat after all. But I was worried...

Koffee

Just a note, I have found that only bike shops carry the 16 gram. All 3 Walmarts - even Gander Mountain (hunting specialty shop) only carry the 12 gram.

I also make sure I rotate my tire air in the spring. Get all that old stale winter air out and put in nice fresh spring time air......

:D Hehe

Listen to me...

I have the same kind of tires as you and I also have a CO2 inflator. The thing is this...16g cartriges CANNOT be bought in bulk. On the other hand, 12g cartriges can. Just go to WalMart and go to the BB gun aisle. Get a 25 pack of BB gun CO2 cartriges. This will cost you about 12 bucks. As for 16g cartriges, they run 3 bucks apiece. If you are concerned about if the 12g will fully inflate it up to 120psi, don't worry. All you have to do is carry an extra cartridge. At 50 cents apiece, it's quite a bargain. Good luck.

EDIT: Overinflating your tires will not cause much damage. There is no big difference between say 120psi and 150. The higher psi, the less chance of getting a flat because surface area of the tire hitting the road is reduced. There are no benefits over 120psi though. Just make sure the pressure is around 120psi. Hope this makes any sense at all.

Also, to efficiently pack your cartridges, place 1 in the pump itself, and then place the other ones somewhere in your pack. Once again, good luck.

A single 12 gram CO2 cartridge will put about 90 psi into your tire...enough to ride home on.

Wal Mart CO2 cartridges are alleged to contain lubricants which will harm the seals in a CO2 inflator. I don't know if this is true or not. I can't imagine why they would damage a CO2 inflator, but not a BB gun. I use Wal-Mart cartridges, figuring that the money I save will offset the cost of a new inflator.

Some inflators allow you to carry a cartridge in them. Others do not. If your inflator allows you to turn the cartridge backwards, store it that way. Don't put a cartridge in an inflator in such a way that the cartridge is punctured and expect to use it at any time in the future. Once punctured, the CO2 cartridge will leak gas, even if it is in the inflator.

Experiment with a CO2 inflator at home, before you need it. Waste a cartridge or two so you know how to use the inflator, and how much pressure you can expect from it.

I'm not crazy about the idea of overinflating tires. You may not have to be super-precise, but if you put enough pressure into a tube, it will blow out.

When I use a CO2 cartridge for a roadside repair, I always top the tire off when I get home, and add air before the next ride. CO2 may leak faster than air, but if you top off before the next ride, you'll be fine.

I always carry an inflator, a patch kit, a spare tube and two CO2 cartridges. I've never needed more than one cartridge, but the second one is insurance.

FWIW, I have just had to use a CO2 cartridge roadside once, and it did seem to leak out quite a bit faster than air. The day after the CO2 infusion, I thought that I had pinched the tube! Pressure was down to something like 45 psi from probably 100+ psi. I pumped it back up to 120 psi using my floor pump, road it for about 15 miles and then let it sit for 2 days. When I measured it again, it was at 110 psi.