a new question: Magnesium
Brad Behm
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
Werehatrack
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.
S. Anderson
news:1045ksu...@corp.supernews.com...
> Is this a pretty good deal?
> pros and cons of magnesium?
> Your opinions are greatly appreciated.
Run away!! Run away!! ;-)
Just my opinion,
Scott..
Gary Perkins
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" <bradbehmdelet...@localnet.com> wrote in message
news:1045ksu...@corp.supernews.com...
Brad Behm
> Run away!! Run away!! ;-)
hmm.. Why do you say that? Just curious.
Thanks,
Andrew
>
> Just my opinion,
>
> Scott..
>
>
TheYvid
> 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
TheYvid
> 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,
S. Anderson
> 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..
maxxevv
Wow ... where's that ? Anywhere online ??
Would be interested in magnesium. Would be glad if you can post
me a link.
Thanks. ;)
--
TomD
ZeeExSixAre
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
Prometheus
<phil_leeIHEA...@hotmail.com> 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.
ZeeExSixAre
> --On Thursday, July 08, 2004 5:51 PM -0400 ZeeExSixAre
> <phil_leeIHEA...@hotmail.com> 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
Chalo
>
> 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=tech&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
bfd
"Chalo" <chump...@hotmail.com> wrote in message
news:8b4b7de4.04070...@posting.google.com...
> "ZeeExSixAre" <phil_leeIHEA...@hotmail.com> 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:
>
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
Jim Smith
> 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.
Werehatrack
>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.
Tim Izod
> --On Thursday, July 08, 2004 5:51 PM -0400 ZeeExSixAre
> <phil_leeIHEA...@hotmail.com> 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.
Chalo
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
LioNiNoiL_a t_N e t s c a p E_D 0 T_N e T
American Racing Equipment has been making magnesium wheels for cars
since 1960, and Bassano Grimeca makes them for bikes now:
http://www.bassanogrimeca.com/images/foto/big/prodotti/ruote4.jpg
--
Robots don't kill people -- people kill people.
http://www.irobotmovie.com/
Alex Rodriguez
chump...@hotmail.com says...
>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).
I forget where I read the article, but I do recall reading an article about
a journalist who wanted ignite a magnesium computer case. I think it was
a Next computer case. He went to a lot of trouble trying to do it, and
it was not easy to do.
--------------
Alex
Ryan Cousineau
Alex Rodriguez <ad...@columbia.edu> wrote:
MacWorld or MacUser. It was for a cover shoot. They wanted to do
something special for either the return of Steve to Apple, the purchase
of NeXT, or the intro of the Power Mac Cube.
The special problem they had was that the Next case had a 1' cube-shaped
shell. It was very hard to get it up to the flashpoint of magnesium.
They went to a...well, a fire-simulation laboratory. The eventual
technique was probably something like a big pile of magnesium shavings
used as kindling, or just a hellaciously hot thermal start.
Once it got burning though, whoa!
--
Ryan Cousineau, rcou...@sfu.ca http://www.wiredcola.com
President, Fabrizio Mazzoleni Fan Club
carl...@comcast.net
Dear Alex,
Yes, the NeXT case was magnesium. That choice of material
and the rest of its design made the case a wonderful example
of imbecile design--your library may have "Steve Jobs & the
NeXT Big Thing" by Randall Stoss, which has a page or two on
all the problems with the NeXT case. It's bad enough to make
you admire modern bicycle design.
Carl Fogel
Ryan Cousineau
carl...@comcast.net wrote:
Mind summarizing? Offhand, I suspect the rather odd magneto-optical
drive and the attempt to do primary ventilation through the MO drive
slot were the big ones. The latter solution was adequate for cooling,
but the dust destroyed the drive.
I had a NextStation (the NeXT slab) with associated monitor for a while,
and it's a pretty nice design. much less aggressively weird than the
cube, and it fit nicely under the monitor. Those 17" grayscale monitors
were a delight to use.
carl...@comcast.net
Dear Ryan,
While the library closes here early on Sunday, I can recall
these problems among others with the magnesium NeXT case.
The case fiasco was driven purely by cosmetics and serves as
an example of the sort of things that kept going wrong when
Steve Jobs controlled things.
Jobs insisted on a special magnesium case, even though this
metal has no engineering advantage over plain sheet steel
for making computer cases.
Magnesium just sounds cool.
Jobs also insisted that the needlessly magnesium case had to
be a true cube with 90-degree angles everywhere. Normally,
casting moulds have a slight and invisible-to-the-eye taper
of about half a degree, just as cake moulds have a much
larger taper to help the baked cake drop out. If you want
no-taper square moulds, they have to come apart in several
expensive directions.
But a perfect cube sounds cool.
Achieving the invisible perfect 90-degree angles required
not only special casting moulds but also touch-up work on
the finished cases that cost the already dead-in-the-water
NeXT company extra millions of dollars.
Jobs also specified a brain-dead flat black paint job.
But "black" sounds cool.
But flat black paint is idiotic because it highlights even
the slightest surface blemishes, which Stoss pointed out is
why car makers reserve the very best sheet metal panels for
the cars that they plan to paint black. With its cool flat
black paint job, the NeXT computer often arrived showing
scuff-marks from normal styrofoam shipping inserts, which
cost NeXT even more money that it couldn't afford.
While Jobs was busy with pointless materials, invisible
angles, and bad paint choices, the rest of the project fell
apart.
Carl Fogel