Ultra Wide Tires vs Narrow Tires - Page 3
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  1. #51
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    Quote Originally Posted by asgelle View Post
    By now, I think most people know this isn't true. Even for smooth roadways, there is a point where surface irregularities cause an increase in RR with increasing tire pressure. https://blog.silca.cc/part-4b-rollin...-and-impedance
    ok ugh,, the break even point for a 25mm Conti on "new asphalt" is over 110 PSI. It's only when you go over 110 PSI will impedance starts to dominate, and you overall rolling resistance starts to increase. 110 psi is pretty damn high to put on a 25mm tire don't you think? But guess what, going much more than 10psi below 110 will also... increase rolling resistance too! And how many times have we've seen folks in here say they run something ridiculous low like "70/75" psi on a 25mm. My general point still stands, people are still under inflating their tires.

    PS: I get a giggle out seeing the "milled pavement" photo in the test. The city had some re surfacing on s section here.. and I would never in a million years subject my enemy to ride on such millled road.. because my damn teeth felt like they were about to fall out. It's a pretty damn point less test as far as I'm concerned, however intriguing it was.

  2. #52
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    Quote Originally Posted by aclinjury View Post
    ok ugh,, the break even point for a 25mm Conti on "new asphalt" is over 110 PSI. It's only when you go over 110 PSI will impedance starts to dominate, and you overall rolling resistance starts to increase. 110 psi is pretty damn high to put on a 25mm tire don't you think?
    Quote Originally Posted by aclinjury View Post
    2. ... So all this bro talk about lower psi equals better rolling only applies to maybe mtb or gravel, but out on the tarmac, you sitll need to pump it as high as the specs allow..
    Was that the goalpost I just saw moving?

    Quote Originally Posted by aclinjury View Post
    But guess what, going much more than 10psi below 110 will also... increase rolling resistance too!
    Yes, but the penalty for being too high is much greater than being too low. This is carefully explained in Josh Poertner's blog at silca.cc.

  3. #53
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    Quote Originally Posted by asgelle View Post
    Was that the goalpost I just saw moving?


    Yes, but the penalty for being too high is much greater than being too low. This is carefully explained in Josh Poertner's blog at silca.cc.
    goal post moving? may tweaked an inch due to new data? but not moving. Sure learn me new data and I'm ready to be learned, nothing wrong with revising my view in light of new data. Agreed?

    But see the bros are talking using almost "gravel like psi" on tarmac, then my emphasis on higher psi still valid. Impedance theory is just one additional data point (in addition to the standard diamond drum test), and impedance data still doesn't support the sort of low psi (70-75) that some of the bros are preaching. What the Michelin data does support is that increasing psi gives lower rolling resistanct up to a point of about 110 psi for a 25mm. Bottomline, if performance is the goal on tarmac, and you're using a 25mm tire, then you need to be at 90-110 psi.

    ps: yes overinflating causes more performance loss than underinflating, but i don't think we need to worry about people over inflating a 25mm past 110 psi since everyone seems to be on the "lower is faster" bandwagon
    Last edited by aclinjury; 03-02-2019 at 11:53 AM.

  4. #54
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    Quote Originally Posted by aclinjury View Post
    goal post moving? may tweaked an inch due to new data? but not moving. Sure learn me new data and I'm ready to be learned, nothing wrong with revising my view in light of new data. Agreed?

    But see the bros are talking using almost "gravel like psi" on tarmac, then my emphasis on higher psi still valid. Impedance theory is just one additional data point (in addition to the standard diamond drum test), and impedance data still doesn't support the sort of low psi (70-75) that some of the bros are preaching. What the Michelin data does support is that increasing psi gives lower rolling resistanct up to a point of about 110 psi for a 25mm. Bottomline, if performance is the goal on tarmac, and you're using a 25mm tire, then you need to be at 90-110 psi.

    ps: yes overinflating causes more performance loss than underinflating, but i don't think we need to worry about people over inflating a 25mm past 110 psi since everyone seems to be on the "lower is faster" bandwagon
    How can you make PSI recommendations without stating rider weight? Yes, 90F 110R PSI for 25mm tires is a good place to be if you are around 200lbs.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

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  5. #55
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    Quote Originally Posted by Lombard View Post
    How can you make PSI recommendations without stating rider weight? Yes, 90F 110R PSI for 25mm tires is a good place to be if you are around 200lbs.
    I'm 220 lbs and rode my 25's at 90 psi front and rear without any pinch flats.

    Now I'm running 4kS in a 28 which measure to almost a 30mm tire at 75 psi at the same weight without pinch flatting.
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  6. #56
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    Quote Originally Posted by aclinjury View Post
    ps: yes overinflating causes more performance loss than underinflating, but i don't think we need to worry about people over inflating a 25mm past 110 psi since everyone seems to be on the "lower is faster" bandwagon
    Everyone? You can't think of even one person not on that bandwagon?

  7. #57
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    Quote Originally Posted by asgelle View Post
    Everyone? You can't think of even one person not on that bandwagon?
    Quite a few of the roadies who came in the shop a few years ago would run on no less than 120 psi, 23s, 25s, whatever. Do recall they were big, heavy guys, so they'd load up the tires, soak up the bumps, and ride comfortably.

    Aclinjury hits it right. This hasn't changed for decades:

    "What the Michelin data does support is that increasing psi gives lower rolling resistance up to a point of about 110 psi for a 25mm. Bottomline, if performance is the goal on tarmac, and you're using a 25mm tire, then you need to be at 90-110 psi."

  8. #58
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    Quote Originally Posted by velodog View Post
    And the Pro's use tubulars at Pari Roubaix, what's your point?

    Well, tubular tires don't pinch flat, so they're great on rough tarmac. Rider can run them at 80 psi. and retain optimum rolling resistance.

  9. #59
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    Quote Originally Posted by Fredrico View Post
    Quite a few of the roadies who came in the shop a few years ago would run on no less than 120 psi, 23s, 25s, whatever. Do recall they were big, heavy guys, so they'd load up the tires, soak up the bumps, and ride comfortably.

    Aclinjury hits it right. This hasn't changed for decades:

    "What the Michelin data does support is that increasing psi gives lower rolling resistance up to a point of about 110 psi for a 25mm. Bottomline, if performance is the goal on tarmac, and you're using a 25mm tire, then you need to be at 90-110 psi."
    Here again, maximum rolling resistsnce on what kind of surface? A test drum isn't the same as real world conditions.
    "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



  10. #60
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    Quote Originally Posted by asgelle View Post
    Everyone? You can't think of even one person not on that bandwagon?
    nope, not a single one. Let me give you an idea why everyone is on the bandwagon. For a person weighing about 125 lbs, in order for him to impart a 15% wheel-drop on a 25mm tire, the pressure needs to be pumped to around 70/75 F/R. This is for a 125 lb person. Most guys in here aren't that, most are in the 160lb plus, yet they're using this sort of psi or even lower. Not optimal. But hey, if YOU want to be comfy and not be performance oriented, then it's ok too. Me, when I'm on a road bike, I want to go fast.

  11. #61
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    Quote Originally Posted by Lombard View Post
    How can you make PSI recommendations without stating rider weight? Yes, 90F 110R PSI for 25mm tires is a good place to be if you are around 200lbs.
    For a person weighing about 125 lbs, in order for him to impart a 15% wheel-drop on a 25mm tire, the pressure needs to be pumped to around 70/75 F/R. This is for a 125 lb person. If you're in the 160-170 lbs class, you need to be at at least 90/100 psi F/R psi to get a 15% wheel drop. There is a chart on this 15% wheel drop but I can't find it at the moment.

  12. #62
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    Quote Originally Posted by Lombard View Post
    Here again, maximum rolling resistsnce on what kind of surface? A test drum isn't the same as real world conditions.
    I'm assuming good tarmac. Hell tarmac on most Socal roads are great, and I'd say on par with the diamond drum.

  13. #63
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    Quote Originally Posted by aclinjury View Post
    nope, not a single one. Let me give you an idea why everyone is on the bandwagon. For a person weighing about 125 lbs, in order for him to impart a 15% wheel-drop on a 25mm tire, the pressure needs to be pumped to around 70/75 F/R. This is for a 125 lb person. Most guys in here aren't that, most are in the 160lb plus, yet they're using this sort of psi or even lower. Not optimal. But hey, if YOU want to be comfy and not be performance oriented, then it's ok too. Me, when I'm on a road bike, I want to feel fast.
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  14. #64
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    couple pics showing typical road surface around here, and pretty much for most of Cali. Sure their are some bad roads, but for the most part, roads here are smooth, I'd say they're "diamond drum" equivalent.

    Ultra Wide Tires vs Narrow Tires-road2.jpg

    Ultra Wide Tires vs Narrow Tires-road1.jpg

  15. #65
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    Quote Originally Posted by aclinjury View Post
    couple pics showing typical road surface around here, and pretty much for most of Cali. Sure their are some bad roads, but for the most part, roads here are smooth, I'd say they're "diamond drum" equivalent.

    Click image for larger version. 

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    Click image for larger version. 

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  16. #66
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    Quote Originally Posted by aclinjury View Post
    For a person weighing about 125 lbs, in order for him to impart a 15% wheel-drop on a 25mm tire, the pressure needs to be pumped to around 70/75 F/R. This is for a 125 lb person. If you're in the 160-170 lbs class, you need to be at at least 90/100 psi F/R psi to get a 15% wheel drop. There is a chart on this 15% wheel drop but I can't find it at the moment.
    Sorry, the numbers don't agree with you. Use the second box and adjust F/R to 45%/55%:

    Bicycle tire pressure calculator
    "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



  17. #67
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    Quote Originally Posted by Fredrico View Post
    Well, tubular tires don't pinch flat, so they're great on rough tarmac. Rider can run them at 80 psi. and retain optimum rolling resistance.
    Yes, they're running larger volume tires at low pressures in a race that spends about 20% of the time on the cobbles and the race is still a race. That's like 200 kilometers of pavement that those low pressures are being used on, and, like I said, it's still a race. Nine out of the last ten editions have had an average of over 40KPH and the one edition of the ten that wasn't over 40KPH averaged 39KPH.

    That's over the whole race, tarmac and pave.

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  18. #68
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    Quote Originally Posted by Lombard View Post
    Sorry, the numbers don't agree with you. Use the second box and adjust F/R to 45%/55%:

    Bicycle tire pressure calculator
    ok let's take a real life scenario of a 170 lb rider, plus the following:

    - bike/pedals: 18 lbs
    - 2 bottles of water: 3 lbs
    - helmet, shoes, apparels: 5 lbs
    - phone, garmin, tool bag, pump, food, whatever else: 5 lbs

    170 + 18 + 3 + 5 + 5 = 201 lbs, we'll call it 200 even.

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    A 170 lb rider should be at 78/97 psi F/R. Isn't this what I said eariler, riders should be at 90-110 psi for best performance (on good tarmac you need less than a 15% drop)? I should add that the 78 psi front is assuming a STATIC load, i.e., you're not getting out of the saddle rocking your bike, because if you do, 78 psi will feel squishy and gives a vague handling feel, so you need to really up it to closer to 90 psi. Anyway numbers are inline with what I'm saying.
    Last edited by aclinjury; 03-03-2019 at 07:48 PM.

  19. #69
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    Quote Originally Posted by velodog View Post
    I get it, you're a slowpoke. Performance doesn't matter. Move along?

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    Quote Originally Posted by aclinjury View Post
    Anyway numbers are inline with what I'm saying.
    Well that’s quite different from what you said earlier. And what about a rider who weighs 110 lbs?
    Quote Originally Posted by aclinjury View Post
    ... but out on the tarmac, you sitll need to pump it as high as the specs allow.

  21. #71
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    Quote Originally Posted by aclinjury View Post
    I get it, you're a slowpoke. Performance doesn't matter. Move along?
    No, you don't get it, but that's all right because the blinders don't allow you to see more than what is in your narrowed field of view. You see a dead horse and you want to beat it, that's okay.

    Sticks and stones dude.
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  22. #72
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    Quote Originally Posted by aclinjury View Post
    ok let's take a real life scenario of a 170 lb rider, plus the following:

    - bike/pedals: 18 lbs
    - 2 bottles of water: 3 lbs
    - helmet, shoes, apparels: 5 lbs
    - phone, garmin, tool bag, pump, food, whatever else: 5 lbs

    170 + 18 + 3 + 5 + 5 = 201 lbs, we'll call it 200 even.

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Size:  49.8 KB

    A 170 lb rider should be at 78/97 psi F/R. Isn't this what I said eariler, riders should be at 90-110 psi for best performance (on good tarmac you need less than a 15% drop)? I should add that the 78 psi front is assuming a STATIC load, i.e., you're not getting out of the saddle rocking your bike, because if you do, 78 psi will feel squishy and gives a vague handling feel, so you need to really up it to closer to 90 psi. Anyway numbers are inline with what I'm saying.
    You really are forcing the issue about "good tarmac". Most of us don't have that.

    Also, I run 70 PSI front all the time. This concept about lower pressure in front feeling "vague and squishy" is BS. Maybe at 50 PSI, it would feel vague and squishy, but not 70. And you're much more likely to recover from a road hazard hit at a lower pressure in front.
    "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



  23. #73
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    Quote Originally Posted by asgelle View Post
    Well that’s quite different from what you said earlier. And what about a rider who weighs 110 lbs?
    with all the back and forth, and I have said in light of the Michelin data I'd review my view,... you'll need to be specific what exact of my statement you're referring to.

    I already spent time replying to Lomdard and his specific calculator and his calculator numbers are inline with what I'm saying, and they are higher numbers compared to some of the bro talks of "lower psi is faster rolling", and that was the main point of what I'm arguing about using the data presented by Velodog and you.

    tell you what, you're a smart guy, instead of trying to play "that's not what I said earlier" and make me do all the reply work, why don't YOU tell us, based on whatever data that's out there, what a 170-lb rider plus bike/gear should be riding at what pressure?? That's probably more meaningful than pissing match..

  24. #74
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    Quote Originally Posted by Lombard View Post
    You really are forcing the issue about "good tarmac". Most of us don't have that.

    Also, I run 70 PSI front all the time. This concept about lower pressure in front feeling "vague and squishy" is BS. Maybe at 50 PSI, it would feel vague and squishy, but not 70. And you're much more likely to recover from a road hazard hit at a lower pressure in front.
    I'm focusing on good tarmac? that's about what I see in for the most part in whole state of Cali. So now you make me wonder what sort of surfaces are the rest of the country is riding on.

    Anyway, I focus on "good tarmac" is because when I state a psi numbers, they have to be in relation to tarmac condition and rider+bike weight. And because the "standard diamond drum" test seems to be assuming a "good tarmac" condition, that's why I said good tarmac.

    Now if YOU want to argue for a lower psi usage based on whatever "crappy tarmac" condition that's out there, then feel free to present your point and data supporting your point, just like what I've done with my case for "good tarmac". This is probably more meaningful then arguing back and forth, agree?

    but if ride on hard dirt pack or half paved surface and 70 psi works for you, then go with it?

  25. #75
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    Quote Originally Posted by aclinjury View Post
    tell you what, you're a smart guy, instead of trying to play "that's not what I said earlier" and make me do all the reply work, why don't YOU tell us, based on whatever data that's out there, what a 170-lb rider plus bike/gear should be riding at what pressure?? That's probably more meaningful than pissing match..
    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,

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