Specialized Secteur - tyres at 60psi???

dg74
dg74 Posts: 656
edited September 2009 in Road beginners
Anyone run their tyres at this low pressure before? Normally I run em at 100psi but the Secteur I'm getting with tyres at 700x25 are set at 60psi.

I can only imagine that this will slow me down. Or will it?

Comments

  • redvee
    redvee Posts: 11,922
    Slow you down, leave you vulnerable to visits from the PF. The handling will feel very different compared to the correct pressure, try doing a corner at speed with 60psi and then do the same corner with 100psi at the same speed. Even a few psi less and I can feel unnerved on my bike.
    I've added a signature to prove it is still possible.
  • What do you mean 'set at 60 psi'? Just pump them up!
  • John.T
    John.T Posts: 3,698
    Instant pinch flats at that plus cr*p handling. Blow them up to the pressure on the sidewall.
  • 115 on mine
  • dg74 wrote:
    Anyone run their tyres at this low pressure before? Normally I run em at 100psi but the Secteur I'm getting with tyres at 700x25 are set at 60psi.

    I can only imagine that this will slow me down. Or will it?
    I see that the tyres have 60TPI in the name:
    'Specialized All Condition Sport, 700x25c, wire bead, 60TPI, w/ Flak Jacket protection'
    but I don't think this means they should be at 60 psi.

    I may be wrong but just thought this may be why you thought they should be set at 60 psi?
  • redvee
    redvee Posts: 11,922
    Got my Ultra Gator Skins pumped upto 95psi and the first few days were boneshaking especially the cobbles I rode over but now used to the pressure.
    I've added a signature to prove it is still possible.
  • Anonymous
    Anonymous Posts: 79,667
    TPI, Threads Per Inch. It is the denseness of the weave of your tyres on the sides. The higher the number, the more puncture protection and tyre strength you have.

    Pump them to 110 psi, notice the difference immediately. :wink:
  • dg74
    dg74 Posts: 656
    Jesus. Some times I am so stupid.

    110 psi it is.
    :oops:
  • can you ever over do the inflating, being new to road biking i am frightened that i put too much air in.
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  • balthazar
    balthazar Posts: 1,565
    Carp.man wrote:
    can you ever over do the inflating, being new to road biking i am frightened that i put too much air in.
    Yes you can. If the pressure is too high, it will blow the tyre off the rim. If this happens in your house it will deafen you; if it happens on the road, it is obviously dangerous. Don't pump tyres up beyond the maximum pressure marked on them.

    Heavy braking on long downhills can cause enough heat that the air pressure increases enough to blow the tyre off. This isn't a problem in the UK – not long enough hills – but alpine cyclists know to ride with lowered pressure in their tyres, especially tandemists. The 'blow-off' point isn't necessarily as high as one might think.
  • balthazar wrote:
    Heavy braking on long downhills can cause enough heat that the air pressure increases enough to blow the tyre off. This isn't a problem in the UK – not long enough hills – but alpine cyclists know to ride with lowered pressure in their tyres, especially tandemists. The 'blow-off' point isn't necessarily as high as one might think.
    Interesting. How does that happen? I understand that the rim would get hot with heavy braking, but I wouldn't have thought this would have increased the air pressure within the inner tube? I'm not questioning that it happens, just interested to learn how it happens.
  • The heat causes the air in the tube to expand, increasing the pressure.
  • balthazar
    balthazar Posts: 1,565
    Interesting. How does that happen? I understand that the rim would get hot with heavy braking, but I wouldn't have thought this would have increased the air pressure within the inner tube? I'm not questioning that it happens, just interested to learn how it happens.

    It's thermal expansion. There are various way-over-my-head articles about it on Wikipedia, such as:

    http://en.wikipedia.org/wiki/Charles%27s_law
  • My Secteur Sport says 115-120psi.
  • Flasheart
    Flasheart Posts: 1,278
    115 psi on my Michelin Pro3 Race
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  • amaferanga
    amaferanga Posts: 6,789
    I've never pumped tyres up beyond 100psi. I don't see the point (I'm not exactly heavy mind) and with roads as they are in the UK I can only imagine that it'd be uncomfortable to say the least.
    More problems but still living....