air in tyre

funkydisciple
funkydisciple Posts: 65
edited July 2011 in Road beginners
I posted a few days ago that due to my weight I should put in more air in the tyre than the recommended psi. I'm not looking to go way overboard with the psi but looking to get the tyre at least at a point that when i press down with my thumb i dont want it to go down at all....but once i'm done putting the air in... when i'm taking the pump off that little bit of air goes out that makes a difference....when you guys sit on the bike do you notice the back tyre goes down just a little bit? is that normal?

Comments

  • Brimstone Magpie
    Brimstone Magpie Posts: 11
    Surely if you've got the right pressure in the tyre a squeeze with thumb will have no impact? Silly question, but are you sure you've got the right inner tube size? The only time I've had real issue with keep the pressure up on my road bike is when some numpty at the lbs put the wrong size inner tube in.

    I usually pump beyond the recommended psi assuming that a little will escape when I removed the nozzle, and cause of your previous thread stick a bit more in for luck.
  • TuckerUK
    TuckerUK Posts: 369
    I'm no expert but I've read that if either tyre doesn't compress slightly under the riders weight then the pressure is too high.
    "Coming through..."
  • jim453
    jim453 Posts: 1,360
    When you disconnect the pump from the valve the noise you hear is air escaping from the hose not the inner tube. Don't worry about it.
  • navrig
    navrig Posts: 1,352
    If you use a track pump that little bit air which escapes is from the hose between the pump and the tyre and is not actually coming out of the tyre.

    Aim for 100-120psi.
  • sungod
    sungod Posts: 17,348
    there'll be some safety margin in the max rating on the tyre, but i'd still be wary of going over it, the rims and rim tape also have a pressure rating

    are you are getting pinch flats when you run the tyres at the middle of their range? if not then can't see why you'd need to go any higher
    my bike - faster than god's and twice as shiny
  • ai_1
    ai_1 Posts: 3,060
    Every pneumatic tyre on any vehicle compresses when you load it. How much it deforms depends on the size and shape of the tyre, the pressure, and the load. If you can't see any compression when you sit on your bike then I reckopn you've over-inflated.
    As I under stand it, the general concensus is that approx 15% compression is typically about optimum for good comfort without impacting performance. That would be a decrease in tyre height of 15% where it contacts the ground when you put the weight of the bike and rider on it. I'm no expert so do check around to see if this figure is correct before relying on it!
    funkydisciple wrote:
    I posted a few days ago that due to my weight I should put in more air in the tyre than the recommended psi. I'm not looking to go way overboard with the psi but looking to get the tyre at least at a point that when i press down with my thumb i dont want it to go down at all....but once i'm done putting the air in... when i'm taking the pump off that little bit of air goes out that makes a difference....when you guys sit on the bike do you notice the back tyre goes down just a little bit? is that normal?
  • rake
    rake Posts: 3,204
    light bikes arent really made for very heavy people. you may never get it to perform at its peak.
  • sub55
    sub55 Posts: 1,025
    rake wrote:
    light bikes arent really made for very heavy people. you may never get it to perform at its peak.
    :roll:
    constantly reavalueating the situation and altering the perceived parameters accordingly

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