Scandium strength?

Discussion in 'Cycling Equipment' started by Adam Huisenfeld, Feb 26, 2003.

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  1. I am a larger rider: 6'3" and weigh around 220 lbs. I have heard contradictory arguments about how
    strong this tubing material truly is. I have heard that it's stronger then 7000 to 7005 tubing.....
    and I have heard that it is weaker. Any opinions or experience regarding Scandium? Please, please,
    PLEASE Email me... [email protected]

    Thank you!
     
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  2. Ant

    Ant Guest

    "Adam Huisenfeldt" <[email protected]> wrote in message
    news:<U_X6a.46503$F%[email protected]>...
    > I am a larger rider: 6'3" and weigh around 220 lbs. I have heard contradictory arguments about how
    > strong this tubing material truly is. I have heard that it's stronger then 7000 to 7005
    > tubing..... and I have heard that it is weaker. Any opinions or experience regarding Scandium?
    > Please, please, PLEASE Email me... [email protected]
    >
    > Thank you!

    http://tinyurl.com/6gp5

    cheers
     
  3. Jon Isaacs

    Jon Isaacs Guest

    >I am a larger rider: 6'3" and weigh around 220 lbs. I have heard contradictory arguments about how
    >strong this tubing material truly is. I have heard that it's stronger then 7000 to 7005 tubing.....
    >and I have heard that it is weaker. Any opinions or experience regarding Scandium?

    Realize that the material properties of the tubing are only part of the equation, the frame strength
    is determined also by the geometric properties of the tubing, ie larger diameters and thicker walls
    make it stronger.

    Fancy alloys with trick names are most often used to make bikes lighter rather than stronger. In my
    opinion it is likely they are less strong simply because the material itself are not significantly
    stronger and yet the manufacturer needs to justify the high price tag with a lighter frame.

    So, at your size, you should not be concerned with the weight of the bike, you should be concerned
    with the strength and stiffness of the frame. A heavier frame can obviously be stiffer and stronger
    and this is what you ought to be looking for IMHO.

    jon isaacs
     
  4. adam-<< I am a larger rider: 6'3" and weigh around 220 lbs. I have heard contradictory arguments
    about how strong this tubing material truly is.

    If the tubing dimensions are similar to other well built aluminum framesets, then it's probably no
    problem. The problem comes when they take this stuff, make it VERY thin walled, in an attempt to
    make it light light and then it becomes fragile.

    What do you want out a frameset? What do you want it to do for you? What kind of riding?

    Very light weigh frameset for you may mean a broken frameset for you- Also look at steel...some
    really nice, not heavy, well riding framesets out there- http://www.nobilettecycles.com

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  5. Bluto

    Bluto Guest

    "Adam Huisenfeldt" <[email protected]> wrote

    > I am a larger rider: 6'3" and weigh around 220 lbs. I have heard contradictory arguments about how
    > strong this tubing material truly is. I have heard that it's stronger then 7000 to 7005
    > tubing..... and I have heard that it is weaker. Any opinions or experience regarding Scandium?

    "7000" alloy is a category, not a specific material.

    7005 alloy is about equal to 6061 in its mechanical properties, but is easier for a bike
    manufacturer to process, as it requires less heat treatment after welding.

    7075 alloy as used in various machined parts is much stronger than 6061, but is not weldable by
    conventional means.

    Scandium-containing aluminum alloy really is strong stuff, with yield strength approaching double
    that of 6061, superior even to 7075. It is weldable by normal processes for aluminum alloys. The
    problem comes when manufacturers use the additional strength of the material to shave weight,
    which generally speaking makes the frame more suceptible to denting and other damage including
    fatigue cracking.

    An intelligently designed scandium-aluminum frame weighing the same as an intelligently designed
    steel frame would last similarly long if not longer, while providing a measure of corrosion
    resistance and the potential for rigidity unattainable by the steel frame. To my knowledge, such a
    frame is not manufactured, nor even an applicable tubeset for such a frame.

    Every scandium-aluminum frame I have seen or heard of falls into the category of "stupid light",
    disposable parts. None are suitable for a heavier rider.

    At your weight, you _want_ a frame over 5 lbs. regardless of how you intend to use it. Because of
    the many design tradeoffs, material tensile strength is a subtlety secondary to smart, mature design
    and an adequate amount of whatever material is used.

    Chalo Colina
     
  6. David Jones

    David Jones Guest

    It's exceptionally durable. It's actually used as a "grain refiner" in aluminum. Scandium was used
    in the guidance fins for ICB missiles as it's so stiff. I have a scandium story. I was in a very bad
    cycling accident on my Wilier Izoard (which doesn't use a replaceable derailleur hanger). At around
    21MPH I slammed the street and bike's hanger was bent in 2 planes BAD. I bent it (and it was VERY
    HARD TO BEND IT BACK) back to normal with hanger tool. I had a similar wreck on a MTB bike and the
    hanger snapped in two.

    -David Jones "Adam Huisenfeldt" <[email protected]> wrote in message
    news:U_X6a.46503$F%[email protected]...
    > I am a larger rider: 6'3" and weigh around 220 lbs. I have heard contradictory arguments about how
    > strong this tubing material truly is. I have heard that it's stronger then 7000 to 7005
    > tubing..... and I have heard that it is weaker. Any opinions or experience regarding Scandium?
    > Please, please, PLEASE Email me... [email protected]
    >
    > Thank you!
     
  7. Ed Ness

    Ed Ness Guest

    Mr. Colina wrote:

    > At your weight, you _want_ a frame over 5 lbs. regardless of how you intend to use it. Because of
    > the many design tradeoffs, material tensile strength is a subtlety secondary to smart, mature
    > design and an adequate amount of whatever material is used.
    >
    > Chalo Colina

    How did you come up with a 5 lbs. plus frame weight number?

    Easton makes a wide varity of Scandium tubing. Assuming the builder knows what they are doing, it
    should be no problem to build a suitable frame for a wide range of riders - including 220+ lb'ers.
    Just tell the builder that you want some of the thicker/stiffer tubes. And just a guess here, but I
    should imagine that a suitable frame should come in well under 4 lbs.

    Check the following link for some tubing information.
    http://www.eastonbike.com/TUBE_SETS/tubes_sc_road.html

    From what I understand, Mandaric builds a nice Scandium frame
    http://www.mandaric.com/index_forum.html

    Also, the Merckx SC model has a solid reputation.
     
  8. chump-<< At your weight, you _want_ a frame over 5 lbs. regardless of how you intend to use it.

    Don't need a frameset that heavy. I approach his weight and have a custom Nobilette steel lugged
    frameset that weighs about 4 pounds. Agree with everything else you say tho, particularly about
    getting a stoopid light frameset when one is .1 offa ton.

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  9. Bluto

    Bluto Guest

    [email protected] (Ed Ness) wrote:

    > Mr. Colina wrote:
    >
    > > At your weight, you _want_ a frame over 5 lbs. regardless of how you intend to use it. Because
    > > of the many design tradeoffs, material tensile strength is a subtlety secondary to smart, mature
    > > design and an adequate amount of whatever material is used.
    > >
    > How did you come up with a 5 lbs. plus frame weight number?

    It's my personal experience. The OP is not just a little heavy for a cyclist, he's kind of tall too.
    220 lbs. was my lightest "fighting weight" during my days as a fast cyclist. At that time I found
    the only lightweight (4 lbs. or less) frame in my size that was suitably stiff was Cannondale's. I
    used Cannondale frames exclusively for many years, but they were subject to some fatigue cracking
    which I regard as a side effect of their light weight. I never tried a Klein frame but I assume that
    they are the functional equivalent.

    The OP might ride a 63cm frame, or a 22" MTB frame. Either of these, when built to weigh much less
    than an actual 5 lbs., would be either quite flexible, prone to fatigue or crash damage, or both.

    I'm not saying that the OP couldn't _get away with_ a 3 to 4 lb. frame. I'm only saying that if my
    experience is any guide, he would be happier with the rigidity and longevity of a 5+ lb. frame.

    > Easton makes a wide varity of Scandium tubing. Assuming the builder knows what they are doing, it
    > should be no problem to build a suitable frame for a wide range of riders - including 220+ lb'ers.
    > Just tell the builder that you want some of the thicker/stiffer tubes. And just a guess here, but
    > I should imagine that a suitable frame should come in well under 4 lbs.

    A suitably *strong* frame perhaps, but that is not a frame's only measure of suitability. The extra
    pound or more can go a long way towards making a frame stable and long-lasting. Ultimately, it's
    much cheaper and more effective to shave weight on the less critical components, while maintaining a
    strong foundation.

    Chalo Colina
     
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