Author Topic: CO2 in tyres  (Read 4914 times)

robgul

  • Cycle:End-to-End webmaster
  • . . cyclist, Cytech accredited
    • Cycle:End-to-End
CO2 in tyres
« on: April 16, 2008, 04:07:12 pm »
I'm sure I've read something about this somewhere ...

On Sunday had a flat at the start of the CTC club run  - replaced the tube (brand new) and because it was cold and the rest of the chaps were itching to move on I used a CO2 cartridge - fine, instant 120psi (wearing gloves so no frozen fingers  ;D )

... today, got the same bike out and the tyre was soft, not flat but approx 50% soft - pumped up with track pump and real air - rode 60 miles, still hard.

Is there something with CO2 that makes it reduce tyre pressure over time .. does it "shrink"?

Rob

Re: CO2 in tyres
« Reply #1 on: April 16, 2008, 04:12:27 pm »
Warning - total guesswork approaching!

Air is mostly N2. CO2 is a smaller molecule than N2, and therefore leaks away faster?X Wrong! See me after class...

Edit: As I suspected, I was wrong. CO2 leaks away faster because it is soluble in latex and permeates through the inner tube.

border-rider

Re: CO2 in tyres
« Reply #2 on: April 16, 2008, 04:12:49 pm »
Butyl will doubtless have a different permeability to CO2 than to the mix of gasses that make up air, but I dunno if it is more or less than the average,

edit: it is, much more:

http://www.bikeforums.net/showthread.php?t=154847

and anyway  I'd not expect tyre pressure to drop by that much since Sunday

I was wrong ;)

robgul

  • Cycle:End-to-End webmaster
  • . . cyclist, Cytech accredited
    • Cycle:End-to-End
Re: CO2 in tyres
« Reply #3 on: April 16, 2008, 04:34:02 pm »
Thank you gentlemen - I shall make sure my pump is working!

... but have to say the "instant high" albeit not long-lasting, from CO2 is worth it when it's cold/wet/dark or any combination thereof.

Rob

Re: CO2 in tyres
« Reply #4 on: April 16, 2008, 04:40:49 pm »
I wonder about the helium Chris Boardman used in his hour attempts.

border-rider

Re: CO2 in tyres
« Reply #5 on: April 16, 2008, 04:48:38 pm »
Helium's the leakiest thing there is.  We used to use it to find leaks in vacuum systems

Plus, hours of fun doing silly voices :)

Re: CO2 in tyres
« Reply #6 on: April 16, 2008, 05:00:07 pm »
Helium's the leakiest thing there is.  We used to use it to find leaks in vacuum systems

Plus, hours of fun doing silly voices :)

I always get the wrong mental image when Ms S's nickname (HK) is mentioned.

Re: CO2 in tyres
« Reply #7 on: April 17, 2008, 12:02:33 pm »
Butyl will doubtless have a different permeability to CO2 than to the mix of gasses that make up air, but I dunno if it is more or less than the average,

edit: it is, much more:

http://www.bikeforums.net/showthread.php?t=154847


I love it when threads descend into critiques of other people's spelling and grammar.

(it's "gases" not "gasses", MV) ;)
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

border-rider

Re: CO2 in tyres
« Reply #8 on: April 17, 2008, 02:25:40 pm »

Biggsy

  • A bodge too far
  • Twit @iceblinker
    • My stuff on eBay
Re: CO2 in tyres
« Reply #9 on: April 17, 2008, 02:44:26 pm »
I love it when threads descend into critiques of other people's spelling and grammar.

(it's "gases" not "gasses", MV) ;)

There is no such fing as correct spelling.  Dictionaries just reflect how the English language is used.  They don't make the "rules" up.  We do.

Gases, gasses, buses, busses...
●●●  My eBay items  ●●●  Twitter  ●●●

Re: CO2 in tyres
« Reply #10 on: April 17, 2008, 08:13:21 pm »
those bikeforums dudes toadally rock!




border-rider

Re: CO2 in tyres
« Reply #11 on: April 17, 2008, 08:19:35 pm »
I think this relates to the way one speaks

Being of Manc origin, I would pronounce the word gass-ez wheras Mrs MV might say gazez

I'd say sing-ing, she'd say singing

Re: CO2 in tyres
« Reply #12 on: April 17, 2008, 08:29:19 pm »
I tend to reserve gasses for the verb form, as in "Farmer Palmer gasses badgers".

We have the same argument over "focused" and "focussed" at work.  It's a common management buzzword.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

donpedro

  • ain`t haulin` any lambs to the marketplace anymore
    • But, I'm Swedish!
Re: CO2 in tyres
« Reply #13 on: April 17, 2008, 09:59:22 pm »
Q: Any chance of a adding spelling-button?  Really miss that from acf.
Not that anyone bother reading my Swenglish nonsens posts any way!  ::-)
"A society is defined not only by what it creates, but by what it refuses to destroy."

Re: CO2 in tyres
« Reply #14 on: April 17, 2008, 10:04:53 pm »
I use the spell checker add on for Firefox. It underlines in red any errors I make but still doesn't stop me posting dire spellings as sometimes I don't seem to see them even so. Sorry mate didn't see that spelling mistake.
I think you'll find it's a bit more complicated than that.

donpedro

  • ain`t haulin` any lambs to the marketplace anymore
    • But, I'm Swedish!
Re: CO2 in tyres
« Reply #15 on: April 18, 2008, 05:56:18 pm »
Thanks! I couldn't get the set up of Firefox to work like I wanted when I tried it. To many functions. Might try once more when I reboted my other pc.

Edit:
As stated before CO2 is addictive. I filled up two 23mm tires with a 16g cartridge after we punctured at the same time due to broken glass. Took us less than 5min to change tubes, search for stuck bits and refill!
"A society is defined not only by what it creates, but by what it refuses to destroy."

robgul

  • Cycle:End-to-End webmaster
  • . . cyclist, Cytech accredited
    • Cycle:End-to-End
Re: CO2 in tyres
« Reply #16 on: April 18, 2008, 06:22:48 pm »
How does a thread about CO2 get morphed into one about Firefox?

Rob

Re: CO2 in tyres
« Reply #17 on: April 18, 2008, 06:28:33 pm »
I once saw a newsgroup thread on nanotechnology run for 18 months and cover pretty much every subject under the sun.  However, this forum is more predictable because any really long thread tends inexorably towards NSFW.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

donpedro

  • ain`t haulin` any lambs to the marketplace anymore
    • But, I'm Swedish!
Re: CO2 in tyres
« Reply #18 on: April 18, 2008, 06:37:07 pm »
How does a thread about CO2 get morphed into one about Firefox?

Rob

Better now? ;)
"A society is defined not only by what it creates, but by what it refuses to destroy."

FatBloke

  • I come from a land up over!
Re: CO2 in tyres
« Reply #19 on: April 18, 2008, 10:12:25 pm »
Helium's the leakiest thing there is.  We used to use it to find leaks in vacuum systems

Plus, hours of fun doing silly voices :)
I thought hydrogen was even leakier, hence the storage problems affecting development of hydrogen infernal combustion engined cars. :-\
This isn't just a thousand to one shot. This is a professional blood sport. It can happen to you. And it can happen again.

border-rider

Re: CO2 in tyres
« Reply #20 on: April 18, 2008, 10:17:06 pm »
I thought hydrogen was even leakier, hence the storage problems affecting development of hydrogen infernal combustion engined cars. :-\

Hydrogen's better at adsorbing onto metal surfaces, but Helium is leakier -  a helium atom is about 1/3 the size of a hydrogen atom