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  1. #1
    Senior Member sabazel's Avatar
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    Duh Question: PSI

    I have a question that probably fits in the "duh" category, but I couldn't find the answer in a search.

    At what PSI should I run my CX tires? For various conditions? I'm a roadie, but after my first race tonight, I have a sneaking suspicion that the PSI was way too high. If not, well, time to look for another excuse.

    I have 700x35 tires.

    Thanks in advance for answering my "duh" question.
    "What is a Tiagra? Is that like a Liger?"

  2. #2
    Slave to my PM
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    There is not one blanket statement, since there a several variables that need to be considered. Are you running tubulars? How much do you way weigh? What are the conditions like?. Generally speaking, I run 30 psi on my front and 35 psi on my back with tubulars, and I weigh 170. I have run lower, but if it is bumpy in spots I tend to bottom out pretty bad. I have never pinch flatted with running as low as 25 psi on the front, but running it that low I think I have just been lucky. When I ran clinchers I usually kept it up around 40 psi.

  3. #3
    Senior Member meanwhile's Avatar
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  4. #4
    Team Beer Cynikal's Avatar
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    I run around 28 lbs in my tubulars when I race and maybe 35 in clinchers. In my clinchers I run Stan's sealant in my tubes to avoid pinch flats.
    I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC

  5. #5
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    Clinchers, 700x34, 170lb body-weight. 37psi front, 41psi rear, or thereabouts. Any lower up front and the tire rolls over too much. The rear is a bit firm, but I'll take that over a pinch flat any day.

  6. #6
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    It's really something you have to experiment with personally. There is a certain knack to riding low PSI, both in terms of turning and in terms of avoiding pinchflats.

    The pressure gauges on floor pumps are inaccurate at low PSI, so get a good one like the Accugage.

  7. #7
    Overacting because I can SpongeDad's Avatar
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    I have had it recommended to me that the top end should be 1/4 of the weight of you plus your bike. For me, that's 45 lbs.

    Last year I progressively when lower - to about 30psi on clinchers, at which point I was pinch flatting. This year I'm doing 35 front/40 back. Even at that, I did manage to pinch flat the rear going over a root as I was grinding around an off camber turn. Did the same turn 5 more times the next day at the same pressure and was fine.

    Tubulars can get lower.
    “Courage is going from failure to failure without losing enthusiasm." (Churchill)

    "I am a courageous cyclist." (SpongeDad)

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