Ultra Wide Tires vs Narrow Tires - Page 4
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  1. #76
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    Quote Originally Posted by asgelle View Post
    As I said earlier, all generalizations are wrong. A 170 lb. rider should start with the 15% drop recommendation and then adjust pressure based on the individual roads he rides on considering several factors among them the balance between speed and his risk of pinch flats or rim damage, comfort, and handling,
    ah ok got it. And that's where I'm coming from too, I just put emphasis for the case of "good tarmac" because I think good tarmac approximates a diamond drum (and we have solid data for diamond drum), but i'm also opened to the Michelin data too, and that I'm assuming most people are riding on good tarmac that sits somewhere between diamond drum and the tarmac in the Michelin test (reasonable?).

    A reason of my seemingly contentious reply is also to get people stop and ask questions whenever they hear another poster says:

    1. lower psi rolls with less resistance
    2. I use 65/70 f/r and it works great
    ...without context whatsoever

    Not here to waste time preaching people. But I'm opened to data, any data, if that means better performance. Those who are happy with 70 psi, great!

  2. #77
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    this morning on a ride i ran across this piece of metal plate on a sidewalk near my house. I thought hmm interesting, it does give a distinct buzziness to the tires that I don't feel on regular pavement. Not sure what the "diamond drum" that they use to test rolling test is, but if it's anything like this metal plate, then it definitely creates more buzziness to the rider than riding on good pavement. Rolling at a constant speed thru this metal plate I can definitely feel the attenuation (when compared to the smooth tarmac on the sidewalk). Not really trying to make a conclusion if a diamond metal drum or "good tarmac" give less rolling resistance, just stating my initial feeling is that the metal plate I rolled thru feels more attenuating than rolling on good tarmac on the road. Another anecdote.

    Ultra Wide Tires vs Narrow Tires-drum.jpg

  3. #78
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    Quote Originally Posted by aclinjury View Post
    this morning on a ride i ran across this piece of metal plate on a sidewalk near my house. I thought hmm interesting, it does give a distinct buzziness to the tires that I don't feel on regular pavement. Not sure what the "diamond drum" that they use to test rolling test is, but if it's anything like this metal plate, then it definitely creates more buzziness to the rider than riding on good pavement. Rolling at a constant speed thru this metal plate I can definitely feel the attenuation (when compared to the smooth tarmac on the sidewalk). Not really trying to make a conclusion if a diamond metal drum or "good tarmac" give less rolling resistance, just stating my initial feeling is that the metal plate I rolled thru feels more attenuating than rolling on good tarmac on the road. Another anecdote.

    Click image for larger version. 

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    4 pages and and it's about time to wonder what the experimental setup actually is. lol.
    Blows your hair back.

  4. #79
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    Quote Originally Posted by aclinjury View Post
    this morning on a ride i ran across this piece of metal plate on a sidewalk near my house. I thought hmm interesting, it does give a distinct buzziness to the tires that I don't feel on regular pavement. Not sure what the "diamond drum" that they use to test rolling test is, but if it's anything like this metal plate, then it definitely creates more buzziness to the rider than riding on good pavement. Rolling at a constant speed thru this metal plate I can definitely feel the attenuation (when compared to the smooth tarmac on the sidewalk). Not really trying to make a conclusion if a diamond metal drum or "good tarmac" give less rolling resistance, just stating my initial feeling is that the metal plate I rolled thru feels more attenuating than rolling on good tarmac on the road. Another anecdote.

    Click image for larger version. 

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    And your point?
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  5. #80
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    Lightbulb

    Quote Originally Posted by den bakker View Post
    4 pages and and it's about time to wonder what the experimental setup actually is. lol.
    yeah lol

  6. #81
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    Arrow

    Quote Originally Posted by Lombard View Post
    And your point?
    see above

  7. #82
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    Quote Originally Posted by aclinjury View Post
    see above
    I think you are forgetting that the surface in the road is flat and not a "drum". That does make a difference believe it or not.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  8. #83
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    Quote Originally Posted by Lombard View Post
    I think you are forgetting that the surface in the road is flat and not a "drum". That does make a difference believe it or not.
    I suppose it depends on which part of the drum you are concerned with? The round part or the flat part? Haha! Sorry, I digress...
    To date, philosophers have merely interpreted the world in various ways. The point however is to change it.

  9. #84
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    Quote Originally Posted by Lombard View Post
    I think you are forgetting that the surface in the road is flat and not a "drum". That does make a difference believe it or not.
    Not really. https://blog.silca.cc/part-4b-rollin...-and-impedance
    Attached Thumbnails Attached Thumbnails Ultra Wide Tires vs Narrow Tires-theoretical_and_real_roller_plus_tom_a_asphalt_grande.png  

  10. #85
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    Quote Originally Posted by aclinjury View Post
    this morning on a ride i ran across this piece of metal plate on a sidewalk near my house. I thought hmm interesting, it does give a distinct buzziness to the tires that I don't feel on regular pavement. Not sure what the "diamond drum" that they use to test rolling test is, but if it's anything like this metal plate, then it definitely creates more buzziness to the rider than riding on good pavement. Rolling at a constant speed thru this metal plate I can definitely feel the attenuation (when compared to the smooth tarmac on the sidewalk). Not really trying to make a conclusion if a diamond metal drum or "good tarmac" give less rolling resistance, just stating my initial feeling is that the metal plate I rolled thru feels more attenuating than rolling on good tarmac on the road. Another anecdote.

    Click image for larger version. 

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    Very interesting. Noticed the same thing every time I ride over one of those idiot things. Chip and seal on farm to market roads in TX feel just like that, except the surface isn't as slippery. We'd immediately feel the difference transitioning to the paved shoulders on the federal highways. Lowering below 90 psi would still feel slow and squishy on the chip and seal, though, so we kept pressure optimized for the smooth shoulders, 95-110 psi.

    The chart says it all: rolling resistance decreases up to 110 psi and increases from impedance above 110 psi--on less than perfect surfaces. Trackies pump up to 120 psi, but they aren't bouncing around on the boards. IME over 40 years on 23, 25, 28, 32 mm tires, road riding is fastest between 90-110 psi, exactly what the graph shows. Above that psi: too much bouncing around every time you hit a bump. Below: too squishy when accelerating, whacking up a hill, or making an emergency maneuver.

    Load up the bike with luggage and it'll feel like its on shock absorbers at 95 psi, nice and cushy but control still optimum. Unloaded, most riders I've talked to prefer the road feel and control at 90-95 psi. That's perfect for a 190# bike and rider on 25 mm, or heck, 28 mm.

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