Pressure loss in tubed tyres with CO2

Discussion in 'Beginners' started by labougie, 13 Nov 2017.

  1. cyberknight

    cyberknight Legendary Member

    Location:
    South Derbyshire
  2. palinurus

    palinurus Guru

    Location:
    Watford
    CO2 molecules are larger than N2 molecules (that make up the bulk of air), but CO2 is more soluble in butyl rubber and diffuses through it at a much faster rate (very approximately 15 times faster)

    Here's a nice chart- X is measure of size, Y of permeability through a rubber
    membrane.

    Generally increasing size does lead to reduced permeability but the effect of increased solubility for CO2 is much larger.

    Anyway, yeah- top it up with air once you get home.
    ZiD6yhY.jpg
     
  3. Paulus

    Paulus Getting older by the minute

    Location:
    Barnet,
    I have a Mini Morph road pump and it is very good. Gets up to 100psi easily. It is also quite light and fits into your back pocket.
     
  4. andrew_s

    andrew_s Guru

    Location:
    Gloucester
    People use CO2 because most modern pumps are slow, or very slow.

    Proper frame fit pumps, which were universal back when all frames were steel, don't fit most modern bikes well, what with sloping top tubes, the lack of pump fittings, hydroformed aluminium, and carbon of any old shape. For most people, it's either a mini pump in a back pocket, or a slightly less mini pump in a clip under a bottle cage.
    Mini pumps don't work well by comparison - they'll take a lot longer to get to a 100 psi riding pressure, if they get there at all.

    The best are the mini track pumps, the best of which are about as good as a smaller frame fit pump. I'd take it that if a rider is carrying one of these, he's not using CO2.
     
    Alan O likes this.
  5. boydj

    boydj Veteran

    Location:
    Paisley
    If you are on a group ride, normally the group will stop if someone has a problem. CO2 helps get everybody moving again with minimal delay. With the small pumps carried by most roadies these days it's hard work getting a tyre up to a reasonably high pressure. The used CO2 canister and the duff tube are taken home to go into the recycling - leave the countryside as you find it.
     
  6. Alan O

    Alan O Über Member

    Location:
    Liverpool
    Ah, the answer to a question I've been meaning to ask - thanks :okay:
     
  7. cyberknight

    cyberknight Legendary Member

    Location:
    South Derbyshire
    And weight weenie ism
     
  8. Reiver

    Reiver Legendary Member Photo Winner

    I don't think the tubes can be recycled so if you put them into the recycle bin they will just go to land fill, what a waste! - they are usually very simple to repair.

    Just because it is possible to recycle the co2 container does not mean it is an environmentally friendly thing to do. Melting down then reforming metal uses a lot of energy, energy that usually comes from fossil fuels and adds to climate change. There is nothing environmentally friendly about it, esp when the whole concept of these canisters is based on laziness. If someone can cycle 30 or 40 mile they have the energy to blow a tyre up with a pump.
     
    Dogtrousers, Duffy and Alan O like this.
  9. iluvmybike

    iluvmybike Well-Known Member

    On that basis then having a bicycle isn't very environmentally friendly then!!
     
  10. Reiver

    Reiver Legendary Member Photo Winner

    depends what you are using it for - if it is instead of a car for your commute then it is very environmentally friendly thing to do. If it's to pointlessly ride round in very big circles (like I do) then it is not very environmentally friendly at all (I guess we will stay healthier and out of hospital and care for longer which is good, but that environmental gain will be lost by all the extra food we eat, and we will probably live longer, and the very worst thing we can do to the enviroment is be alive)
     
    Dogtrousers likes this.
  11. boydj

    boydj Veteran

    Location:
    Paisley
    I usually do repair tubes - and what is acceptable in council recycling varies widely from area to area. As far as canisters go, then recovering metal by recycling is far more environmentally friendly than creating new metal from ore, and every little helps.
     
  12. mjr

    mjr Wanting to Keep My EU Citizenship

    Not producing the metal waste in the first place is friendlier!

    Tubes are accepted in the tyre bins at some recycling centres.
     
    Dogtrousers likes this.
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