Tire Inflation Pressure

Discussion in 'Cycling Equipment' started by beeker, Jun 28, 2003.

  1. beeker

    beeker New Member

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    I am new to biking so this may be a little basic but here we go anyway.

    When I started out, my biking buddy told me to run my tubulars at about 100-110 psi, but now that he has gone back to Nepal and I am on my own, I looked at the Continental Sprinters I am running an noticed that they have a maximum of 170 psi. I noticed a couple of posts that have people running up in the 180-190 range.

    Since I am running about 205 lbs, my thought is that more psi is better - lower rolling resistance.

    So, should I crank those babies up to 170 or just leave them down in the 110 range. Anyone with the time to give a primer on tire pressures? Thanks in advance.

    Beeker
     
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  2. rek

    rek New Member

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    I don't know if there are a different set of recommendations for tubular tyres, but 170+ psi strikes me as a crazily high pressure. Maybe if you were on a time trial or something where every millisecond counts .. ? But it would be seriously uncomfortable.

    Many moons ago I found this graph of recommended tyre pressures for different weights and sizes.. anyone care to comment on its validity?
     
  3. slug

    slug New Member

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    The 170 psi listed on the tire sidewall is not the recommended pressure, it just lets you know what the maximum pressure is. Racers like to pump tires up to there maximum to get the most efficiency and thus speed. But recreational riders are better off using a lower psi for better comfort because the lower pressure tire acts like a shock absorber.

    I was recently running 125 psi and was told by some tire dealers that was even a little too high. I now run about 105 psi. I weigh 170 lbs. and my bike is 20 lbs, so according to the chart posted previously, I should be running 97.5 psi. I'd say the chart is pretty close, but of course this is really a subjective opinion since it comes down to a trade off of comfort for efficiency.

    slug
     
  4. mnetherc

    mnetherc New Member

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    I know the question related to tubulars, but something I never realised (with clinchers) is that the rims also have a max inflation pressure, in addition to the tyres.

    For eg if you take a look at any of the wheelsets or rims on www.mavic.com and they have a listing of the max inflation pressures for each tyre size in use with their rims.

    See the following link for a bit of an overview, although it relates to some $$$$ Zipps specifically:
    http://www.velonews.com/tech/report/articles/4177.0.html

    Just thought I would mention this as I always thought it was the tyre max inflation pressure which was important, I never realised the rims had a max inflation pressure either (for clinchers that is, dont know about tubulars).
     
  5. late

    late New Member

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    Use the high end of the reccomeded range. Higher pressures cause more problems than they cure. That chart doesn't impress me much. It seems to say my wife should run her 25c Fortezzas at
    62.5 pounds. I don't think so.
     
  6. jeanremi

    jeanremi New Member

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    Blow up your clinchers to 10 BAR at least ( What this is in PSI, i don't know), my experience in this matter is that i have not had any punctures ( touch wood), and there is less rolling resistance.
    Little sharp slices of crap like sharp rock, glass , etc are resisted. The proof of this is that my team mates pump theirs up less and are always experiencing punctures, so go ahead, give it a max! But be careful in the wet weather during races( downhill cornering) it grips a little less, so adjust accordingly
    J-R
     
  7. drewjc

    drewjc New Member

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    my personal opinion on this is that you shouild use close to the maximum pressure documented on the sidewall of the tyre. This allows the tyre to work at it's optimum level in regards to rolling resistance, the comfort factor is also one to look at although with tubulars they tend to be more comfortable at high pressure than clinchers anyway. The rim pressure does not apply to tubulars as all of the pressure is on the tyre casing itself as opposed to the rim. If i were you i would be running about 160-170 psi. the tyres are designed to handle this pressure and they wont be as uncomfortable as u may be lead to believe (an inherent advantage of tubulars) good luck.
     
  8. ajo

    ajo New Member

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    The ideal (fastest) pressure is not the highest. To high pressure means that the tire (and wheel/bike) has to bounce up and down when rolling over all small stones and uneven parts of the road "stealing" energy(speed). The pro's know better - typically using 100 psi (7 BAR) on road races with 22/23 mm tires. + 1 bar (15 psi) for 20 mm tyres + 1 bar for very smooth road surface. (This is typical for a 150 pound rider - increase the pressure for heavier riders according to the table.)
    I think the table of reccommended pressure is OK - but I would add approx 20 psi to all.
     
  9. dfgrayb

    dfgrayb New Member

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    I have seen this chart. As to its validity...I don't know.

    My wife, who can do centuries at about 12 mph, weighs 160 with her bike, riding on 28s. This chart suggests we have her at about 60 psi. The minimum on her tire is 115.

    Something is wrong with something or someone (maybe me).
     
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