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  1. #1
    Have bike, will travel Barrettscv's Avatar
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    Air pressure. Fill to the max for speed or less for comfort?

    I have 700c x 28 Continental Gatorback. I will fill them to 100+ psi two times a week or more.

    At that pressure, they roll well and minimize the risk of pinch flats. However, the ride is noticeably busy.

    After two or three days, the ride quality improves as the pressure drops to about 80 psi.

    Should I keep the pressure high at 100 psi, or am I just unnecessarily punishing myself?
    When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.

  2. #2
    bcc
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    I keep mine topped up to the top for the reasons you mentioned. You could always keep them around 80psi if you prefer that - you might find you still only need to refill them a couple of times a week. Ultimately I'd say do whatever helps you get out and ride

  3. #3
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    25c's on my fixed I run at full psi and suffer, for comfy rides I have 32c knobbies on my cyclocross that I run at full psi (85) and don't worry about the 1-2 mph I may lose. The roads are rough in Chicago and I learned my lesson with a serious pinch flat that nearly destroyed my rim thanks to some unmarked road work in the bike lane.

  4. #4
    Senior Member sumguy's Avatar
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    full psi. hate the sluggish feeling when pressure drops.

  5. #5
    The "now retired" Old Guy Ed in GA's Avatar
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    At my weight, I kind of think they should be at full pressure all of the time.
    "The problem with America is stupidity. I'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself?"

  6. #6
    NeoRetroGrouch
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    Quote Originally Posted by Barrettscv View Post
    I have 700c x 28 Continental Gatorback. I will fill them to 100+ psi two times a week or more.

    At that pressure, they roll well and minimize the risk of pinch flats. However, the ride is noticeably busy.

    After two or three days, the ride quality improves as the pressure drops to about 80 psi.

    Should I keep the pressure high at 100 psi, or am I just unnecessarily punishing myself?
    Run them at 80 as long as you don't pinch-flat. Testing shows that HIGH PRESSURE= FASTER= MYTH. Your tire is your suspension. Many think that the higher pressure is faster because it feels faster. Which feels faster - a Jeep CJ going down the road at 55mph or a Lexus going down the same road at 85. With high pressure, every time you hit a small imperfection/bump in the pavement, the full mass of the bike/rider has to go up to get over it. The energy required to go up that fraction of an inch is supplied by you pedaling. How many thousands of times would this be on a normal ride? Total them all up and how big of a hill did you just climb? With low pressure, the tire casing flexes and the rider/bike just goes straight. - TF
    Last edited by TurboTurtle; 10-02-08 at 01:30 PM.

  7. #7
    Senior Member funrover's Avatar
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    On my road/commuter I run 110 p.s.i. it helps me prevent flats!

  8. #8
    Senior Member piper_chuck's Avatar
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    Here's some interesting reading: http://sheldonbrown.com/tires.html#pressure
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  9. #9
    Banned. Mr. Beanz's Avatar
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    I keep mine at 120 (23 and 25's). Maybe I'm nuts but I feel no difference when I run lower psi. But I also feel no difference with a cf fork and/or seatpost either when others swear by them!

  10. #10
    Senior Member Indie's Avatar
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    I run my tires at full pressure. Any comfort that may be gained by riding on soft tires is negated by the extra effort it takes to move the bike forward.
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  11. #11
    NeoRetroGrouch
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    Quote Originally Posted by Indie View Post
    I run my tires at full pressure. Any comfort that may be gained by riding on soft tires is negated by the extra effort it takes to move the bike forward.
    That's really not true. You're beating yourself up to go slower. - TF

  12. #12
    Senior Member DieselDan's Avatar
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    Depends on what kind of riding I will be doing. Riding my MTB with 2.2" slicks, I'll ride around 45-50psi for simple neighborhood cruising, but pump them to the max (65psi) for a serious training ride. The road bike is a bit different, but I know on rougher chip and seal roads in Darlington and Lee Counties I drop them down to 105psi for a somewhat softer ride, but on better roads here in Beaufort County I pump to the max (120psi).
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  13. #13
    Senior Member CACycling's Avatar
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    TT, I'm confused by your box vs. bullet comparison (CJ vs. Lexus). The different feeling of speed is primarily the noise of wind hitting all those flat surfaces of the CJ and the (typically) larger lugged tires on the CJ slapping the pavement vs. an aerodynamic shape with tires designed to be smooth and quiet on the road. Not sure how that equates to tire pressure.

  14. #14
    Clydeasaurus tomdaniels's Avatar
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    Quote Originally Posted by CACycling View Post
    TT, I'm confused by your box vs. bullet comparison (CJ vs. Lexus). The different feeling of speed is primarily the noise of wind hitting all those flat surfaces of the CJ and the (typically) larger lugged tires on the CJ slapping the pavement vs. an aerodynamic shape with tires designed to be smooth and quiet on the road. Not sure how that equates to tire pressure.

    He was trying to explain that the worse suspension (jeep or high pressure tires on bike) makes you feel like you are going faster than you really are. The smoother ride (lower pressure or Lexus) makes the speed less noticeable.
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  15. #15
    Senior Member daintonj's Avatar
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    Quote Originally Posted by Mr. Beanz View Post
    I keep mine at 120 (23 and 25's). Maybe I'm nuts but I feel no difference when I run lower psi. But I also feel no difference with a cf fork and/or seatpost either when others swear by them!
    I do the same but I think the cf fork and seatpost do make a difference in reducing the faint buzz alu frames have.

  16. #16
    Senior Member CACycling's Avatar
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    Quote Originally Posted by tomdaniels View Post
    He was trying to explain that the worse suspension (jeep or high pressure tires on bike) makes you feel like you are going faster than you really are. The smoother ride (lower pressure or Lexus) makes the speed less noticeable.
    I knew where he was going, just don't think it is a fair analogy as the suspension (AKA tire pressure) is only one of many significant differences between these vehicles leading to the percieved speed.

    Now if he said a Lexus with underinflated tires got better mileage (ie: used less energy to move the vehicle down the road) than one with fully inflated tires, that would have been a fair analogy.

  17. #17
    Infamous Member chipcom's Avatar
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    I run mine (23 and 25) at 120 and I really don't consider the ride quality that bad...until I get on my commuter with the 32c TT2000s.

    Keep them pumped up to a level appropriate to your weight to prevent pinch flats.
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  18. #18
    Senior Member racethenation's Avatar
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    Quote Originally Posted by CACycling View Post
    Now if he said a Lexus with underinflated tires got better mileage (ie: used less energy to move the vehicle down the road) than one with fully inflated tires, that would have been a fair analogy.
    Yes, but that would not be correct. I think the analogy is bad either way, but I have never seen anything to support better gas mileage at a lower tire pressure than recommended.

  19. #19
    Galveston County Texas 10 Wheels's Avatar
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    My Buick gets better mpg with PSI Maxed Out in the tires.
    So I do the same on the road bike.
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  20. #20
    ..... Jynx's Avatar
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    Keep them around 90 - 95 psi. 80 seems a little low and may be prone to pinch flats.

  21. #21
    Senior Member CACycling's Avatar
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    Quote Originally Posted by racethenation View Post
    Yes, but that would not be correct. I think the analogy is bad either way, but I have never seen anything to support better gas mileage at a lower tire pressure than recommended.
    Thanks. That was the point I was was hoping someone would get. Why would it take LESS energy to move a bike with underinflated tires when it takes MORE energy to move a car with underinflated tires? Regardless, I know I am slower when my tires are down 20 psi. Don't need a guage to tell me they are low, I can feel it when I ride.

  22. #22
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    10 Wheels has a point there. I don't see how having lower tire pressure could equal the efficiency of having higher tire pressure. Even in a car, you'll get noticeably lower mpg if you have lower tire pressure even by 5 psi. Your engine has to work a little bit more because their is more tire making contact with the road. Same formula would apply to a bicycle. TurboTurtle, you can't convince me that having lower tire pressure is equal to a higher one. The less contact a tire makes, the more efficient the motorThat's why hybrids and high fuel economy cars have tires that make less contact with the road. This same formula would apply to a bicycle, being that the vehicle is the bike and the motor is the rider, each pedal stroke would benefit more from having fully inflated tires. Of course, the trade off is rougher ride, but that would depend on the individual's taste.

  23. #23
    Senior Member George's Avatar
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    Michelin tires says if your over 180 to fill to the max as on the sidewall
    George

  24. #24
    fc_
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    Ok, maybe I'm a physical oddity, but I seem to get better speed and more comfort with my tires at around 80-90psi (panaracer pasella tg, 28 or 35c depending on the bike I'm on). I also notice a notable level of discomfort above that psi range (I think they're rated at 120 psi).

    Find what works for you, and stick with it. Its your butt in the saddle after all.

  25. #25
    Triathlon in my future??? flip18436572's Avatar
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    I run around 110 - 120. The difference down to 80 is terrible for speed difference, and also too easy for a pinch flat with my 23's.
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