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Daft Question # 27658. Tyre pressures Front / Back.

Discussion in 'Bicycle Mechanics and Repairs' started by Elmer Fudd, 21 Oct 2007.

  1. Elmer Fudd

    Elmer Fudd Miserable Old Bar Steward

    How come when I check my tyre pressures ( 80lb"2 ) I always have to put more in the front tyre than the back ? As in yesterday, 30lb front, 10lb back.

    If I go up a kerb, I do it at a dropped kerb if possible, if not I slow right down, in both cases I 'hop' up the kerb.

    I would have thought the back wheel would take the most punishment pressure wise as there is more direct weight over it.

    BTW newish tube in front, thought I might have copped a puncture the other morning but pressure this evening still at 50lb so it's not that.

    Yours
    Confused of Durham
     
  2. Tubes are slightly porous, your front is simply slightly more porous than your rear. Are you running Schrader or presta valves? Schrader valves have a screw in valve core which, if not screwed in tight enough, will let air escape. Youll need a valve core key to tighten it, available from motor accessory retailers.
     
  3. John Ponting

    John Ponting Über Member

    Location:
    Herts
    for MY information:

    I have 3 grandsons under 11 years, all have bikes, all get visited by the fairy too frequently, grandad mends holes in tubes.

    What is the current forum view on green slime as a prophylactic? Does it work on small thorn holes? Does it slow down pressure loss through porous tubes?
     
  4. I once worked in a cycle shop which had the maintenance contract for all the bikes on the Sony Film studio lot, bikes for security staff, load carriers for shifting film stock around etc. We replaced twenty or more tubes a week, until that is I had the bright idea of installing slime filled tubes to them. It took a while for the shop owner to realise that the repair contract was diminishing in value and another while for him to realise why. I got such a bollocking!
     
  5. Elmer Fudd

    Elmer Fudd Miserable Old Bar Steward

    That explains it then, new tube on front bought from Halfrauds (on a Sunday morning), the valves BTW are presta.

    Because I have to use a valve adaptor (Schraeder type pump) I always wrap a bit of P.T.F.E. tape round the presta valve threads et voilà ! No leaking air when I pump up my tyres.
     
  6. John Ponting

    John Ponting Über Member

    Location:
    Herts
    I feel a visit to my lbs for 3 bottles of slime on Monday.