Aerodynamics wheels and tire size??

Discussion in 'Cycling Equipment' started by Goldenboy, Jul 15, 2003.

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  1. Goldenboy

    Goldenboy New Member

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    I was on a ride over the weekend with a friend and I noticed that he was able to hold his speed better than me when coasting down hills. He had this advantage over the other riders in the pack as well. He is running 30mm aero Mavic Cosmics with 18c tires. I am running 23mm Ksyrium Elites with 23c tires and he has about 40 pounds on me. We are both running clichers at about 125psi. Does his setup have that much of an advantage or is my bike underperforming?? He was able to save valuable energy while the rest of us were spinning at the lower slopes of hills. I actually seemed to coast better than most other riders so I assume it to be his wheel/rim combo.
     
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  2. Goldenboy <[email protected]> wrote:
    >I was on a ride over the weekend with a friend and I noticed that he was able to hold his speed
    >better than me when coasting down hills. He had this advantage over the other riders in the pack as
    >well. He is running 30mm aero Mavic Cosmics with 18c tires. I am running 23mm Ksyrium Elites with
    >23c tires and he has about 40 pounds on me.

    If he's 40lbs heavier, there's the answer right there.
    --
    David Damerell <[email protected]> flcl?
     
  3. On Wed, 16 Jul 2003 02:00:25 +0950, Goldenboy wrote:

    > I was on a ride over the weekend with a friend and I noticed that he was able to hold his speed
    > better than me when coasting down hills. He had this advantage over the other riders in the pack
    > as well. He is running 30mm aero Mavic Cosmics with 18c tires. I am running 23mm Ksyrium Elites
    > with 23c tires and he has about 40 pounds on me.

    Ding!

    > We are both running clichers at about 125psi. Does his setup have that much of an advantage or is
    >my bike underperforming?? He was able to save valuable energy while the rest of us were spinning at
    >the lower slopes of hills. I actually seemed to coast better than most other riders so I assume it
    >to be his wheel/rim combo.

    Oh sure, it's his 18mm tires and deep aero rims. The 40 lbs of weight he has over you has no effect
    whatsoever....

    Sheesh.

    --

    David L. Johnson

    __o | Become MicroSoft-free forever. Ask me how. _`\(,_ | (_)/ (_) |
     
  4. Werehatrack

    Werehatrack Guest

    On 16 Jul 2003 02:00:25 +0950, Goldenboy <[email protected]> may have said:

    >I was on a ride over the weekend with a friend and I noticed that he was able to hold his speed
    >better than me when coasting down hills. He had this advantage over the other riders in the pack as
    >well. He is running 30mm aero Mavic Cosmics with 18c tires. I am running 23mm Ksyrium Elites with
    >23c tires and he has about 40 pounds on me. We are both running clichers at about 125psi. Does his
    >setup have that much of an advantage or is my bike underperforming?? He was able to save valuable
    >energy while the rest of us were spinning at the lower slopes of hills. I actually seemed to coast
    >better than most other riders so I assume it to be his wheel/rim combo.

    If he's 40 pounds heavier, there's most of your answer. On the other hand, he has to haul that extra
    40 pounds *up* the slopes, too. TANSTAAFL.

    ---
    My email address is antispammed; pull WEEDS if replying via e-mail.

    Yes, I have a killfile. If I don't respond to something, it's also possible that I'm busy.
     
  5. Goldenboy

    Goldenboy New Member

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    Yes he is 40 pounds heavier. But so were many other riders, and then some. I could roll just as well as them if not better. But 'DING' oh yeah, I put that in the original post but you must not have read the whole thing. It is NOT that simple, but I guess on here -- everyone is an expert.
     
  6. Ted Bennett

    Ted Bennett Guest

    Goldenboy <[email protected]> wrote:

    > Yes he is 40 pounds heavier. But so were many other riders, and then some. I could roll just as
    > well as them if not better. But 'DING' oh yeah, I put that in the original post but you must not
    > have read the whole thing. It is NOT that simple, but I guess on here -- everyone is an expert.

    I look forward to Goldenboy's explanation of how hub bearing friction overwhelms all other forces.

    --
    Ted Bennett Portland OR
     
  7. On Thu, 17 Jul 2003 15:31:29 +0950, Goldenboy wrote:

    > Yes he is 40 pounds heavier. But so were many other riders, and then some. I could roll just as
    > well as them if not better. But 'DING' oh yeah, I put that in the original post but you must not
    > have read the whole thing. It is NOT that simple, but I guess on here -- everyone is an expert.

    Now, don't get your knickers in a knot. You did not say that you rolled as fast as other riders who
    were as heavy as the guy in question.

    The thing is, a hefty gain in mass, for a modest gain in drag, is going to have a whole lot more
    impact on descending speed than a couple of millimeters in tire width, or a more aero rim. Look at
    the size of the tire and wheel's cross section. It just isn't big enough to make that much
    difference on downhilling.

    I usually outdistance by far most of the riders I ride with on downhills. Part of that is certainly
    my avoirdupois advantage, and the rest is the fact that I learned how to downhill when I was young
    and immortal, so I am less timid than most. But the width of my tires is irrelevant.

    --

    David L. Johnson

    __o | I don't believe you, you've got the whole damn thing all wrong. _`\(,_ | He's not the kind
    you have to wind-up on Sundays. --Ian (_)/ (_) | Anderson
     
  8. Goldenboy <[email protected]> wrote:
    >Yes he is 40 pounds heavier. But so were many other riders, and then some. I could roll just as
    >well as them if not better.

    Then something's suboptimal with their machines. If this guy's 40lbs heavier than you and has
    nothing wrong with his bike, there's nothing that can make you coast downhill as fast on an upright
    as he will.

    >It is NOT that simple,

    It _is_ that simple, actually.
    --
    David Damerell <[email protected]> Kill the tomato!
     
  9. Andy Coggan

    Andy Coggan Guest

    "David Damerell" <[email protected]> wrote in message
    news:Ucw*[email protected]...
    > Goldenboy <[email protected]> wrote:
    > >Yes he is 40 pounds heavier. But so were many other riders, and then some. I could roll just as
    > >well as them if not better.
    >
    > Then something's suboptimal with their machines. If this guy's 40lbs heavier than you and has
    > nothing wrong with his bike, there's nothing that can make you coast downhill as fast on an
    > upright as he will.

    With a really good tuck position and semi-aero equipment, I can coast downhill as fast as friends
    who outweigh my by 40 lbs, but who pay less attention to aerodynamic details. However, when one or
    more of them minimizes their drag by also assuming a really good tuck, they will pull away from me -
    even on box section wheels.

    To state it another way: 40 lbs is a lot, but it doesn't *necessarily* guarantee that somebody will
    outcoast you.

    Andy Coggan
     
  10. Mark Hickey

    Mark Hickey Guest

    David Damerell <[email protected]> wrote:

    >Goldenboy <[email protected]> wrote:
    >>Yes he is 40 pounds heavier. But so were many other riders, and then some. I could roll just as
    >>well as them if not better.
    >
    >Then something's suboptimal with their machines. If this guy's 40lbs heavier than you and has
    >nothing wrong with his bike, there's nothing that can make you coast downhill as fast on an upright
    >as he will.
    >
    >>It is NOT that simple,
    >
    >It _is_ that simple, actually.

    Guess that's why they call them the LAWS of physics, huh?

    Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
     
  11. Mark Hickey

    Mark Hickey Guest

    "Andy Coggan" <[email protected]> wrote:

    >With a really good tuck position and semi-aero equipment, I can coast downhill as fast as friends
    >who outweigh my by 40 lbs, but who pay less attention to aerodynamic details. However, when one or
    >more of them minimizes their drag by also assuming a really good tuck, they will pull away from me
    >- even on box section wheels.

    If anyone can out coast Andy on a less aero bike, you KNOW they're being helped by their weight.

    For a matter of comparison, a friend of mine who outweighs me by around 20 pounds (9kg) and I did a
    roll test down a steep hill on our almost identical Habaneros once, swapping wheels on the
    alternate runs.

    With aero wheels (Shamals), I could hang right beside him.

    With my light box section "climbing wheels", he easily dropped away from me.

    Or to put it another way (oversimplifying and leaving out a host of variables), it appears that 20
    pounds is about as much an advantage as aero wheels when coasting down that particular hill.

    Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
     
  12. Mike S.

    Mike S. Guest

    > >With a really good tuck position and semi-aero equipment, I can coast downhill as fast as friends
    > >who outweigh my by 40 lbs, but who pay less attention to aerodynamic details. However, when one
    > >or more of them minimizes their drag by also assuming a really good tuck, they will pull away
    > >from me - even on box section wheels.
    >
    > If anyone can out coast Andy on a less aero bike, you KNOW they're being helped by their weight.
    >
    > For a matter of comparison, a friend of mine who outweighs me by around 20 pounds (9kg) and I did
    > a roll test down a steep hill on our almost identical Habaneros once, swapping wheels on the
    > alternate runs.
    >
    > With aero wheels (Shamals), I could hang right beside him.
    >
    > With my light box section "climbing wheels", he easily dropped away from me.
    >
    > Or to put it another way (oversimplifying and leaving out a host of variables), it appears that 20
    > pounds is about as much an advantage as aero wheels when coasting down that particular hill.
    >
    > Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

    ...and people still wonder about aero wheels...

    Mike
     
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