a new question: Magnesium

Discussion in 'Cycling Equipment' started by Brad Behm, Feb 29, 2004.

  1. Brad Behm

    Brad Behm Guest

    Hello, I posted the question below about my bent frame. Thank you everyone for your excellent
    advice. Anyway I found what looks to be a good deal on a magnesium frame. But I know nothing about
    magnesium frames. Apparently it's a little like al. right? but lighter?

    This is what I found: Merida magnesium 909 road frame with carbon ahead fork for $250

    Is this a pretty good deal? pros and cons of magnesium? Your opinions are greatly appreciated.

    Thanks again,

    Andrew
     
    Tags:


  2. Werehatrack

    Werehatrack Guest

    On Sun, 29 Feb 2004 22:02:36 -0800, "Brad Behm"
    <[email protected]> may have said:

    >Hello, I posted the question below about my bent frame. Thank you everyone for your excellent
    >advice. Anyway I found what looks to be a good deal on a magnesium frame. But I know nothing about
    >magnesium frames. Apparently it's a little like al. right? but lighter?
    >
    >This is what I found: Merida magnesium 909 road frame with carbon ahead fork for $250
    >
    >Is this a pretty good deal? pros and cons of magnesium? Your opinions are greatly appreciated.

    Magnesium is generally more brittle than aluminum. Most items advertised as "magnesium" are actually
    an Al/Mg alloy; in my experience, the more aluminum in such an alloy, the better.

    I do not affirmatively know of any specific drawback in the Merida 909, but the fact that they're
    billing it as magnesium would be enough to put me off. That's just a personal opinion based on
    experience in the automotive and industrial lift truck fields combined with cynicism about buzzwords
    and hype in general.

    --
    My email address is antispammed; pull WEEDS if replying via e-mail.
    Typoes are not a bug, they're a feature.
    Words processed in a facility that contains nuts.
     
  3. S. Anderson

    S. Anderson Guest

    "Brad Behm" <[email protected]> wrote in message
    news:[email protected]...
    > Is this a pretty good deal? pros and cons of magnesium? Your opinions are greatly appreciated.

    Run away!! Run away!! ;-)

    Just my opinion,

    Scott..
     
  4. Gary Perkins

    Gary Perkins Guest

    Had a Merida Magnesium 907 that broke at the seat tube after about 1,000km. That's OK cause
    Merida replaced it with a carbon frame under warranty so all good in the end as the new frame
    seems great so far.

    For what it's worth it looked like a design problem with the original frame rather than a material
    weakness that caused the break. Re-enforcing tube inside the seat tube was too narrow and offered no
    extra strength to the seat tube???? How the hell would I know anyway I just ride it :)

    Cheers Gary

    "Brad Behm" <[email protected]> wrote in message
    news:[email protected]...
    > Hello, I posted the question below about my bent frame. Thank you everyone for your excellent
    > advice. Anyway I found what looks to be a good deal on
    a
    > magnesium frame. But I know nothing about magnesium frames. Apparently
    it's
    > a little like al. right? but lighter?
    >
    > This is what I found: Merida magnesium 909 road frame with carbon ahead fork for $250
    >
    > Is this a pretty good deal? pros and cons of magnesium? Your opinions are greatly appreciated.
    >
    > Thanks again,
    >
    >
    > Andrew
     
  5. Brad Behm

    Brad Behm Guest

    > Run away!! Run away!! ;-)

    hmm.. Why do you say that? Just curious.

    Thanks,

    Andrew

    >
    > Just my opinion,
    >
    > Scott..
     
  6. TheYvid

    TheYvid Guest

    Brad Behm wrote:
    > Hello,

    Hello!

    > Anyway I found what looks to be a good deal on a magnesium frame. But I know nothing about
    > magnesium frames. Apparently it's a little like al. right? but lighter?

    Funny - I was very curious about comparison of a marvellous Magnesium metal properties in theory and
    in practice and actually I started quite a similar discussion on a Polish bicycle newsgroup
    (pl.rec.rowery) just Yesterday - and it goes on;

    Merida seems to be the company that started dealing with this metal as a frames' material for a
    relatively large scale.

    And it seems that being the first is not always easy; a few opinions that have already emerged from
    the discussion mentioned are that the frames made in 2003 (MTB ones actually) were braking
    "constantly" on the seat tube/top tube welding, and this was due to a not to the bad material
    properties, but to the design. According to frame user (who actually broke a few of them in a few
    months, and a company (in Poland) replaced them immediately with no complaints (which is
    unfortunately not a rule)) the cause appeared to be a plastic "sleeve" put inside the seat tube to
    make a smaller-dimension seat post fit.

    That "intelligent" solution seemed to concentrate stress and cause a failure quite soon - so
    wasn't working with magnesium at all (as might do with Cro-Mo possibly, although being not a good
    idea anyway).

    When this "sleeve" was finally gotten rid of everything else with a frame is perfect. The warranty
    is given (by Merida) for 3 years (as for aluminium frames), in contrary to carbon ones with only 1
    year warranty.

    A huge advantages are
    - weight
    - damping properties (in theory 100 times better then with aluminium - and the rider I mentioned
    says the difference (compared to the alu) was really noticeable indeed).

    A disadvantage is a low corrosion resistance of magnesium in general, so the surface coating must
    cover the frame tight, and possible big scratches don't seem be good for the frame.

    Courious about Mg made parts' users pionions too!

    Greetz

    --
    TheYvid I seek You at 49894592
     
  7. TheYvid

    TheYvid Guest

    Werehatrack wrote:
    > Magnesium is generally more brittle than aluminum. Most items advertised as "magnesium" are
    > actually an Al/Mg alloy;

    What do you mean? In this case all aluminium alloy frames should be called magnesium ones since Mg
    is one of the major additives of 6000 and 7000 aluminium series.

    > in my experience, the more aluminum in such an alloy, the better.

    The typical Mg alloys contain up to 10% aluminium and a 6% Al addition combines optimal strength and
    ductility. So for some reason "the more aluminium, the better" doesn't seem to make sense.

    Regards,

    --
    TheYvid I seek You at 49894592
     
  8. S. Anderson

    S. Anderson Guest

    "Brad Behm" <[email protected]> wrote in message
    news:[email protected]...
    > hmm.. Why do you say that? Just curious.
    >
    > Thanks,

    Heehee..I'm sort of a retro-grouch, and a bicycle to me is much like a hammer, not a work of art.
    I've seen some Mg parts and they usually corrode very quickly and are quite brittle. Not to say you
    can't do it. If it's designed properly around the relative strengths and weaknesses of that
    material, you should be OK. But I'm not convinced that Merida frames meet that criteria. I have a
    similar dislike for composite frames. This comes from several bad experiences with carbon fibre
    frames back in the early '90's. Frames with a thousand k's on them and you could pull the drop-outs
    out of the forks with your bare hands. I'm sure some of the newer frames, particularly the Trek
    OCLV's, are somewhat better, but even they have plenty of failures. Unfortunately I sound like a
    crochity old guy when I say this (I'm only 34!!) but steel is real. If you're not doing Alpe d'Huez
    with 195 other guys in July on TV, I'm not sure Mg is the path to get where you want to be. OTOH,
    $250 for any good frame is pretty fair deal, especially if it fits you perfectly!

    Cheers,

    Scott..
     
  9. maxxevv

    maxxevv New Member

    Joined:
    May 31, 2004
    Messages:
    56
    Likes Received:
    0
    Wow ... where's that ? Anywhere online ??

    Would be interested in magnesium. Would be glad if you can post me a link.

    Thanks. ;)
     
  10. Tomd

    Tomd Guest

    maxxevv <[email protected]> wrote in message news:<[email protected]>...
    > Brad Behm wrote:
    > > Hello, I posted the question below about my bent
    > > frame. Thank you everyone for your excellent advice.
    > > Anyway I found what looks to be a good deal on a
    > > magnesium frame. But I know nothing about magnesium
    > > frames. Apparently it's a little like al. right? but
    > > lighter? This is what I found: Merida magnesium 909
    > > road frame with carbon ahead fork for $250 Is this a
    > > pretty good deal? pros and cons of magnesium? Your
    > > opinions are greatly appreciated. Thanks again, Andrew
    >
    >
    >
    > Wow ... where's that ? Anywhere online ??
    >
    > Would be interested in magnesium. Would be glad if you can
    > post me a link.

    http://www.chucksbikes.com/
     
  11. Zeeexsixare

    Zeeexsixare Guest

    maxxevv wrote:
    > Brad Behm wrote:
    > > Hello, I posted the question below about my bent
    > > frame. Thank you everyone for your excellent advice.
    > > Anyway I found what looks to
    > be a > good deal on a magnesium frame. But I know
    > nothing about magnesium > frames. Apparently it's a
    > little like al. right? but lighter? > This is what I
    > found: Merida magnesium 909 road frame with carbon ahead
    > > fork for $250
    > > Is this a pretty good deal? pros and cons of
    > > magnesium? Your
    > opinions > are greatly appreciated.
    > > Thanks again, Andrew
    >
    >
    >
    > Wow ... where's that ? Anywhere online ??
    >
    > Would be interested in magnesium. Would be glad if you can
    > post me a link.

    That would be so cool if it were actually (pure) magnesium.
    You could set one portion aflame and it would erupt in a
    gigantic fireworks display. You could then say, "I could
    have either ridden it or set it on fire... the fire was so
    much more fun!"

    --
    Phil, Squid-in-Training
     
  12. Prometheus

    Prometheus Guest

    --On Thursday, July 08, 2004 5:51 PM -0400 ZeeExSixAre
    <[email protected]> wrote:

    > That would be so cool if it were actually (pure)
    > magnesium. You could set one portion aflame and it would
    > erupt in a gigantic fireworks display. You could then say,
    > "I could have either ridden it or set it on fire... the
    > fire was so much more fun!"
    >
    > --
    > Phil, Squid-in-Training

    Unfortunately for you and the other pyros, this stuff isn't
    pure magnesium. I saw some examples of what I assume is
    similar stuff at SAE World Congress, and its a
    magnesium/aluminum alloy, that has strength properties
    similar to magnesium but can be worked and machined like
    aluminum. And its
    1/3 the weight of aluminum. But, its 3 times the price (per
    weight, which isn't how you buy stock). So given those,
    the pricing is similar to aluminum as well. Looks like it
    might have a future in the automotive industry, so it may
    make it into mainstream bikes before too long as well.

    Mike Mechanical Engineering 2006, Carnegie Mellon University
    Remove nospam to reply.
     
  13. Zeeexsixare

    Zeeexsixare Guest

    Prometheus wrote:
    > --On Thursday, July 08, 2004 5:51 PM -0400 ZeeExSixAre
    > <[email protected]> wrote:
    >
    >> That would be so cool if it were actually (pure)
    >> magnesium. You could set one portion aflame and it would
    >> erupt in a gigantic fireworks display. You could then
    >> say, "I could have either ridden it or set it on fire...
    >> the fire was so much more fun!"
    >>
    >> --
    >> Phil, Squid-in-Training
    >
    > Unfortunately for you and the other pyros, this stuff
    > isn't pure magnesium.

    Well, of course!

    I saw some examples of what I assume is similar stuff at
    > SAE World Congress, and its a magnesium/aluminum alloy,
    > that has strength properties similar to magnesium but can
    > be worked and machined like aluminum. And its 1/3 the
    > weight of aluminum. But

    Innnnteresting....

    > 3 times the price (per weight, which isn't how you buy
    > stock). So given those, the pricing is similar to aluminum
    > as well. Looks like it might have a future in the
    > automotive industry, so it may make it into mainstream
    > bikes before too long as well.

    But this $240 frame can hardly be the kind of alloy you
    speak of. It probably doesn't have anything special in it
    other than the regular amount of mag that's alloyed with
    aluminum for 6061 and such.

    --
    Phil, Squid-in-Training
     
  14. Chalo

    Chalo Guest

    "ZeeExSixAre" <[email protected]> wrote:
    >
    > That would be so cool if it were actually (pure)
    > magnesium. You could set one portion aflame and it would
    > erupt in a gigantic fireworks display. You could then say,
    > "I could have either ridden it or set it on fire... the
    > fire was so much more fun!"

    Pure magnesium would be useless for a bicycle frame, just
    like pure aluminum is useless for that purpose. However,
    there are several structural alloys of Mg that have been
    used for bike frames in the past, by Kirk Precision and
    Litech among others. Merida has been using magnesium alloy
    for some time:

    http://www.merida.com/s0_global/main_control.php?group0=tec-
    h&group1=magnesium&group2=0&

    It's only 2/3 as dense as aluminum, and similarly less stiff
    and less strong. So most of the benefits, characteristics
    and tradeoffs of aluminum frames will also be exhibited in a
    magnesium frame.

    I am curious as to how well magnesium copes with fatigue.

    FWIW, I have machined magnesium structural alloys before,
    and their shavings burn similarly to those of pure
    magnesium. It would be tough to spot-heat a piece as large
    as a bike frame enough to ignite it, without resorting to
    something like an oxyacetylene torch, though.

    Chalo Colina
     
  15. Bfd

    Bfd Guest

    "Chalo" <[email protected]> wrote in message
    news:[email protected]...
    > "ZeeExSixAre" <[email protected]>
    > wrote:
    > >
    > > That would be so cool if it were actually (pure)
    > > magnesium. You could
    set
    > > one portion aflame and it would erupt in a gigantic
    > > fireworks display.
    You
    > > could then say, "I could have either ridden it or set it
    > > on fire... the
    fire
    > > was so much more fun!"
    >
    > Pure magnesium would be useless for a bicycle frame, just
    > like pure aluminum is useless for that purpose. However,
    > there are several structural alloys of Mg that have been
    > used for bike frames in the past, by Kirk Precision and
    > Litech among others. Merida has been using magnesium alloy
    > for some time:
    >
    I would recommend staying far away from the Kirk Precision
    Mg frames. JUNK! You never ever see one as just about every
    single one broke! This may be the last remaining one alive:

    http://www.firstflightbikes.com/KirkPrecision.html
     
  16. Jim Smith

    Jim Smith Guest

    [email protected] (Chalo) writes:

    > FWIW, I have machined magnesium structural alloys before,
    > and their shavings burn similarly to those of pure
    > magnesium. It would be tough to spot-heat a piece as large
    > as a bike frame enough to ignite it, without resorting to
    > something like an oxyacetylene torch, though.
    >

    I know for a fact that a medium sized camp-type fire will
    readily ignite one of those magnesium alloy engine cases
    from an old air-cooled volkswagen, with spectacular results.
     
  17. Werehatrack

    Werehatrack Guest

    On 8 Jul 2004 19:11:50 -0700, [email protected] (Chalo) wrote:

    >I am curious as to how well magnesium copes with fatigue.

    In my experience, very poorly.

    One stunning example: For their 1970 model, Volkswagen
    increased the amount of Mg in the alloy for their engine
    block. They'd been having some problems with the blocks for
    the 1500 and 1600 engines, and I heard that the expectation
    was that the stiffer alloy that they could get by going to
    a higher Mg content would reduce the rate of certain
    failures. They'd been having a problem with bearing saddles
    wallowing out, and with cylinder head studs shearing out
    threads in the block It turned out to be a really bad move.
    With the stiffer high-Mg alloy, the studs took longer to
    pull out, but the blocks were cracking in a dozen places
    where they'd never had problems before, including across
    the bearing saddles, down the back of the block at the base
    of a cylinder, etc. For 1971, they reduced the Mg content
    and changed a couple of other things, and the cracking
    problem vanished.

    I've heard numerous disparaging remarks about Mg as a major
    component of Mg-Al alloys from a couple of metallurgists
    over the years, one of whom was in R&D with a major fastener
    manufacturer for quite a while. He commented that it made
    alloys that were really nice to work with, but if you used
    too much Mg, the material got very brittle.
    --
    Typoes are a feature, not a bug. Some gardening required to
    reply via email. Surrealism is a pectinated ranzel.
     
  18. Tim Izod

    Tim Izod Guest

    Prometheus <[email protected]> wrote:
    > --On Thursday, July 08, 2004 5:51 PM -0400 ZeeExSixAre
    > <[email protected]> wrote:

    >> That would be so cool if it were actually (pure)
    >> magnesium. You could set one portion aflame and it would
    >> erupt in a gigantic fireworks display. You could then
    >> say, "I could have either ridden it or set it on fire...
    >> the fire was so much more fun!"
    >>
    >> --
    >> Phil, Squid-in-Training

    > Unfortunately for you and the other pyros, this stuff
    > isn't pure magnesium.
    [snip]

    No, but if you put enough energy into it you can
    still make it burn. Iron dust, zinc dust, aluminium
    filings and even aluminium bodied pencil sharpeners
    were all found to burn with a nice bright flame in
    our undergraduate labs. Though the bright light had
    the downside of causing the imminent arrival of a
    grumpy lab technician telling us we were supposed to
    be doing chemistry and not playing:)

    --
    Tim.
     
  19. Chalo

    Chalo Guest

    Jim Smith <[email protected]> wrote:
    >
    > [email protected] (Chalo) writes:
    > >
    > > FWIW, I have machined magnesium structural alloys
    > > before, and their shavings burn similarly to those of
    > > pure magnesium. It would be tough to spot-heat a piece
    > > as large as a bike frame enough to ignite it, without
    > > resorting to something like an oxyacetylene torch,
    > > though.
    >
    > I know for a fact that a medium sized camp-type fire will
    > readily ignite one of those magnesium alloy engine cases
    > from an old air-cooled volkswagen, with spectacular
    > results.

    It takes a little while to ignite, though, because the
    case's thermal conductivity requires that the whole case be
    brought close to the ignition temperature before any one
    part of it can reach that temperature. It's not something
    one could do to a bike frame, laptop computer, or crankcase
    with just a match or a cigarette lighter (though those means
    will ignite shavings nicely).

    Chalo Colina
     
Loading...
Loading...