Facts, Not Fiction

 
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    #11
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    Quote Originally Posted by polevaultpower View Post
    This wouldn't dramatically increase the height of the PV
    It probably wouldn't affect heights at all, but it sure would save a lot a hair-pulling when you order a pole by a specific flex number and find out, as you say, the pole doesn't actually meet your expectations. I can think of two times we were stuck with a pole that the vaulter couldn't use.
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    #12
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    Need to have a PVer do a PhD in Material Science/Physics.
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    #13
    Quote Originally Posted by polevaultpower View Post
    This wouldn't dramatically increase the height of the PV, but a feasible improvement is in the technology we use to flex the poles. Deflection testing does not tell the whole story as to how stiff the pole will feel when actually used for pole vaulting.

    A crossbar has a flex number. The cardboard tube your pole ships in has a flex number.

    Two poles that are the same length and measured as the same flex number can feel really different depending on the sail piece and other factors.

    If it were profitable I'm sure this issue would have been resolved decades ago. But there isn't that much money in the pole industry.
    In golf, deflection testing was used to test shaft stiffness for years. On OTC clubs the flex is usually just called, flexible, standard, stiff, and extra-stiff, but like poles, there is a lot more there.

    My clubs were 1/2" long, which makes them less stiff, but they were tipped 1 1/2 inches, which is cutting off the far end, and getting the final flex point closer to the head, which makes them more stiff.

    In the 80s club manufacturers, at the high end, and most of the pros, went to frequency matching for shafts, which takes all these variables into account. As Becca said, not that much money in pole industry, but frequency matching could be done to more precisely measure poles stiffness, and flex points.
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    #14
    is a flex point the same thing as a sail piece?
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    #15
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    Quote Originally Posted by Merner521 View Post
    is a flex point the same thing as a sail piece?
    No... poles start with rectangular sheets of fiberglass. Then a trapezoid shaped sheet of fiberglass is added, the size and shape of this sail piece plays a big role in how stiff the pole is and how it bends, etc.

    The flex number is how manufacturers measure the stiffness of a pole and assign the weight rating. A pole is placed between two points that are at a set distance based on the length of the pole. A 50 pound weight is hung from the middle. The amount of deflection in the pole (how far it goes down) is the flex number. Stiffer poles have a lower flex number.

    It has been the same system since the early days of fiberglass poles.
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    #16
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    Quote Originally Posted by polevaultpower View Post
    A 50 pound weight is hung from the middle. The amount of deflection in the pole (how far it goes down) is the flex number.
    Still?! I thought they had a machine now that bent the pole by pushing from both ends and measured the stiffness.
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    #17
    Quote Originally Posted by Atticus View Post
    Still?! I thought they had a machine now that bent the pole by pushing from both ends and measured the stiffness.
    Isn't that machine just there to make sure that poles don't break when stressed?
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    #18
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    I thought the sail (triangular pieces) created the point that the pole bends when actually vaulting. The farther from the boot the sail is placed the higher the bend point is---- correct?
    Tom Hyland:
    "squack and wineturtle get it"
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    #19
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    Quote Originally Posted by Atticus View Post
    Still?! I thought they had a machine now that bent the pole by pushing from both ends and measured the stiffness.
    That is not used to measure stiffness, it is something Gill started doing when they first started having problems with the carbon poles breaking a dozen years or so ago.
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    #20
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    Quote Originally Posted by wineturtle View Post
    I thought the sail (triangular pieces) created the point that the pole bends when actually vaulting. The farther from the boot the sail is placed the higher the bend point is---- correct?
    It is shaped like a trapezoid, not a triangle. It does affect where the pole bends, but not as precisely as the way you are thinking.

    How a pole bends depends somewhat on the construction of the pole, but it also depends on what the vaulter does at takeoff.
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