Bicycle Mechanics - Does co2 leak faster than air?

Because I do not have a decent pump, I've been using co2 cartridges to fill up my tires. I've found after a week or so, enough co2 has leaked out of the tires to necessitate topping them off again, which means another co2 cartridge down the drain. Is this just the nature of the beast with co2? Are the molecules smaller, or are my tubes just crummy?

Yes, I am going to buy a regular pump, but I'm still curious about this. My tubes are Kenda and I fill them to about 80 psi, I consider 40-50 "time for a refill". Would butyl tubes make a difference?

Rob

I have been using co2 air pump for about 5 years and have noticed no real difference in time. Things you need to look at are how much riding do you do. And in the summer time when it gets hot then cools down you will lose air in your tire. I try not to use co2 to top off as it is expensive to replace the cylinders. I use it when I have a flat on the way to work. You may want to look into a good floor pump for home someone is always having a sale on those things.

Robzr,
I have used Co2 a few times on the trail when my floor pump is not with me. I have not had this problem. The only thing that I can think of might be that either your tubes are somehow having a big problem holding air because they are worn or are just old or defective in some way. Some other things: Do you live in a cool climate? Do your tires sit on a cement floor, such as in a garage, for storage? Do you gauge the tire pressure by how the tire feels from the outside, or do you actually use some sort of tire gauge?
A decrease in air pressure such as what you described, however, in only a week, would lead me to believe that there is something wrong with the tubes. Valves can be defective and leak. This is where you could be losing the air so rapidly. If both of your tires have this problem, then this probably isn't your problem.

Hope I brought something up that might be the problem!

-Moab

All tyres loose air.Some faster than others.Get a pump.The nitrogen in air has bigger atoms too.

I just ordered a mongoose floor pump from Performance ($39 reduced to $15). I gauge it with a Accugauge, ride and store it in chicago summer (70-90 degrees), and it sits on my wooden apartment floor when not in use. The tubes are like 35-38 size which is larger than my rims (the bike shop I got my bike at threw them in free). I have some other tubes I bought, butyl but 22-28 size. Can I use those in 700/30 tires? (ATB Allterrainasaurus 700-30/32c).

I would like to try something other than the oversize Kendas. Can anyone recommend a good tube, regardless of price for hybrid riding (limestone trails, pavement, very mild offroad)?

Also, how tight should I make the nut at the base of the Presta valve (the one that holds the valve to the rim, not the cap or little nut under the cap).

Thanks

Rob

28 tubes work ok in 30 tires,tubes stretch.Latex tube leak quicker than butyl.The cement floor business is a load of bull hockey as are minor temp differrences. the stem nut should not be tight.If the tube shifts in the tire a too tight nut will cause the stem to tear from the tube.You dont even need the nut.Others will differ, but any argument for the nut is bull hockey.

minor temp changes do not make a difference but temp changes do make a difference (its physics dude) I will try to make it short and simple as we all know when things get hot they expand and when the cool down they shrink or compress, air molecules included. So when it is 80F outside than it drops to lets say 65F at night, which it does here a lot that is a 15 degree temp change. now for some other factors to figure in when riding on the street you are riding on asphalt of conrete (usually) both these products absorb and radiate heat, and are usually hotter than the air temp around them add to that the friction that is being caused by th rubber meeting the road when you ride in hot weather you do not fill your tires to the max and that you should check your tire pressure everytime you ride in one day your tires can experiance as much as a 30 degree temp change. So in hot weather you may need to top off your tires more often. I make it a practice to check my pressure daily it only takes a minute. And if you are talking about the nut for a presta valve, no you really don't need it but it doesn't hurt to have it on there it does make it easier to put you pump on it, and harder to break it.

CO2 is slightly corrosive so I suppose it could slowly be degrading your tubes in some way...:confused:

Thanks for the physics lesson dude,and hot damm i'll be sure to be on the lookout for friction on the pavement too.Put all that stuff in your worry basket and throw it in the river.

Yes, a CO2 molecule is a bit larger than an N2 molecule, but I cannot believe either gas should leak out faster than the other. Get yourself a decent high-pressure floor pump to top off your tyres every few days, and get a decent full-size frame-fit pump (Blackburn, Zefal HP-X, etc.). Those CO2 cartridges are a waste of money and resources.

At least get a mini pump. CO2 carts are best used for fast trailside repairs in a race situation or where weight is a concern NOT for normal inflation. Waste of money and resources.:rolleyes:

I can't remember where I read this but someone once stated, that the C02 is a temporary fix to get you home, and that the tyre should be deflated when home and pumped up again with "normal" air. It might have been on the C02 pump instructions?

CHEERS.

Mark

Anybody ever noticed liquid in their tubes after being filled and topped up several times with CO2?

My CO2 "pump" was upgraded to a frame pump after the #@%&* thing broke while trying to repair a roadside flat 12 miles from home, used up 2 cartridges, and still left me with a flat tire.

Mark, That's exactly what my LBS mechanic told me. I was told that CO2 leaks through the pores of the tube much faster than air, and that's been my experience, too.

FWIW, I have to top off my road bike tires every time I ride. Even over a 24 hour period, it's not unusual for them to lose 10 psi or more.

Sue

I cannot imagine not owning a good floor pump.

I'm pretty anal about my tire pressure and if I
had to crack a cartridge everytime I topped off
I'd have to get a second job.

C02 is great for the road or on the trail.