skycomag

i thinking of getting a co2 inflater. i do carry a mini pump.
since my tire required pressure of 70-80 psi.
i thought if i need to repair a tire i would pump with the mini to about 20 psi then top of with the co2.
2 question:
1) how much psi does the co2 inflater inflate to?
2) which is a good one to get ?

thanks for your input in advance,
mitch

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HillRider

The pressure a CO2 cylinder produces depends on the size of the tire and the size of the cyclinder. A 12 gm cylinder will get a 700x23 to near 100 psi, A 16 gm cylinder will produce about 130 psi in the same tire. Larger tires (MTB and larger road) will obviously get to lower pressure. Innovation makes good inflators.

DiabloScott

That's a little higher than I've seen. But it also depends on how much air is in the tube when you pull the trigger. Skyco wants to start with 20 psi already in the tube so he's going to see a lot higher. Usually people who think they want to do this think the pressure won't be high enough with just the CO2 cart and once they see it's fine they skip the pump. It does help to have a little air just to give the tube some shape before you install it, and you do have to make sure the tube's in there just right before you inflate and a pump can help with that. But once you've done a few you realize you can just skip the pump and everything's fine.

His 70-80 psi and his avatar make me think he's got 700x32 tires or similar so 16g carts would be the way to go.

HillRider

I do the same thing. I use my mini-pump to get 20-30 psi in the replacement tube to be sure it's seated properly and the tube itself is good before using the CO2 (12 gm and 700-23 in my case) to bring it up to full pressure. I've seen a couple of damaged tubes and/or improperly seated tire beads in the heat of a roadside flat repair that I want to be sure everything is good before committing to the CO2.

BTW, 12 gm unthreaded cartridges can be very cheap as they are used in paint ball and "BB" guns. You can buy boxes of 15 or 25 at $.50 each or less at any X-Mart. 16 gm and any threaded cartridge are much more expensive.

cycle_maven

Here's what I know:

1) A 12-gram cartridge filling a 700x23 tire brings it to 90 PSI. I measured this.
2) PV=nRT, where P is pressure, V is volume, n is the number of gas molecules, R is a constant and T is temperature.
3) From 1 and 2, and that the temperature is nearly constant, we can calculate the increase in pressure any tire will have after any Co2 cartridge:
a) 12 gram into 700x32 will add 46 pounds.
b) 12 gram into 700x20 will add 119 pounds.
c) 16 gram into 700x35 will add 52 pounds.
d) 12 gram into 700x26 will add 70 pounds.

and so on...

What I do is carry a combo Co2/mini pump, 2 12-gram cartridges and pump the tire up some before shooting a cart into the tire. Not ideal or accurate, but it gets me home...

rydabent

I have had mini pumps fail me in multiple ways, two of them just flat broke when I tried to use them. I carry one for emergencies, but I carry CO2 cartridges and use them first.

JTGraphics

I have been using a Innovation 2nd wind its a CO2 and hand pump in 1 so no need to carry around 2 pumps.
Works great on the road for what you are talking about.
2nd Wind Road - Carbon Mini

digibud

As an aside I'd mention the other day when I swapped tires from my studded mtn tires to my 1.5" street tires and failed to inflate enough to properly seat the bead. A few miles down the road I realized both tires were going thunk-thunk. My hand pump would have been really hard to use to get the pressure high enough to seat the bead but it took two seconds on each tire with my C02. I use one 16gram cartridge on a 25c tire and it's enough to allow me to continue riding without fighting with a hand pump (which I also carry in case of a serious problem).

AltheCyclist

I actually do the opposite - use the inflator to get started (say, up to 20 PSI) and then use pump to get to 60-80 PSI, depending on bike.
Probably doesn't matter, I've found the inflators are just a convenience to save that 1/3 of pump time. In winter when it's really cold out, the inflators are a little bit wasteful; I've had them fully discharge on me when installing the valve, likely because the metal was so cold.

skycomag

DIABLOSCOTT
"His 70-80 psi and his avatar make me think he's got 700x32 tires or similar so 16g carts would be the way to go." good eye actually there 700cx35. the original tire on the bike had psi of 35-65. my new tires are forte metro k they take 80-90 (stated on the tire) psi but keep them at 60. lots of speed bumps(tree roots) on our bike paths

deacon mark

Not to steal the thread but how many times have you goofed up and the co2 discharged. I am the dummy for sure. 1st flat I tried it on I never thought about doing a practice run and the learning curve is not bad bit I let it all out. Now I carry 2 cartridges with me right? Well I messed up again and lucky still carry a mini pump. After that i went home and practiced after this. Well one other time I tried to get it all perfect and sure enough it was cold and ops.

Moral is a small mini pump I can get to 80 that gets you going.

RaleighSport

I almost went that route myself, but I've got a mini pump and a genuine ultraflate, I love that I can throw any cartridge in it and that it actually has a casing grip around the co2 cartridge itself.

Your inflator doesn't have a lock to prevent puncturing ahead of time?

deacon mark

Oh it does I just got fumbling hands. You would think years of jazz guitar and repairing expensive guitars I could hold the thing correct.

WickedThump

I recently got an Innovation Ultraflate. In addition to inflating tires, it shoos away wasps really well.

HillRider

I've had a couple of mini-pumps fail too and the cause was water that got into the pump and rusted the ball checks to the point they wouldn't seal. The problem with mini-pums is they are used so rarely and subject to really abusive conditions routinely so they aren't tested often and are in bad shape when you really need them. Moral: see if your mini-pump works with some regularity. Get the bad news when it doesn't count.

DMF 

Here's an odd question: If I mount a mini-pump to the seat tube, would it be better to mount it upside down? Rationale being that water can't get into the shaft from above. (If that doesn't make sense, by all means say so.)

HillRider

That should help but wheel spray can get water in them no matter how they are oriented. Some of mine have a rubber boot that covers the valve hole but that isn't perfect either. I expect the only real way to protect one of these things is to carry it in a rack pack or inside an under-saddle pack. Or, never ride in the rain.

DMF 

Heck, rain is my favorite riding buddy! Keeps all the other a**holes away.

catonec 

It takes alittle practice but this works well for me. I also carry a lezyne pressure drive backup

https://www.genuineinnovations.com/bicycle/road-tri-athlete/air-chuck-elite.html

2manybikes

Inovations has a tire size - cartridge size - pressure chart on their web pages.

It's about right. But temperature and slightly different size tires from different makers all marked the same size, change things a little.

gforeman 

I really like this one: Portland Design Works Shiny Object CO2 Inflator

https://www.amazon.com/Portland-Desig.../dp/B003M2PNGY

skycomag

aftervchecking varies site, decided on this one because of the features: Genuine Innovations Ultraflate Plus.

thanks to everyone for your imput,
mitch


https://www.genuineinnovations.com/bi...s-clone-2.html

WickedThump

The chart on Innovations site explains a lot. I bought an ultraflate because it can use the inexpensive CO2. Now I see why I might want to carry extras.

2manybikes

Me too, except an older version. I buy the 12 gram threaded cartridges at Walmart for 50 cents each. A box full at one time, maybe 24 in a box, I forget.
They are also used in air guns/bb guns, I carry three cartridges. I usually just use one for a 23mm tire. I don't need the highest pressure in that tire. If I want higher pressure, I put in 10-20 lbs with my mini pump, first. It's much easier to pump first at low pressure.
The temperature of the ambient air changes the pressure too. They don't work well at 20F. One needs to warm them up under your coat first..

Edit: oops, I mean unthreaded

mmmdonuts

Good choice. That's about as versatile as they come.