Magnesium bikes (Merida MTB)

depends on the alloy. and how recent this second hand frame is. if it's newer, it should be ok.

iirc, some of the tdf frames were magnesium this year. mtb forks have been made of cast mag
alloys for ages.

one reason some people have concerns is that magnesioum alloys tend to have low ductility at room
temperatures. being as most high strength alloys tend to be a bit ductility challenged, i wouldn't
say this is necessarily a big problem.

if you want to be definitive, find out what the alloy is, then look up the specific modulus and
compare that with your alternatives. specific modulus is stiffness/density. "normal" steel, aluminum
and titanium bike alloys tend to be very comparable. as far as i'm aware, it's only exotics like
some of the lithium aluminum alloys and 6Al-4V titanium alloys that show any significant departure
from the norm.

jb

Marten Hoffmann said:

In the past, Kirk made bicycles out of magnesium. Nowadays, only Merida makes them. I can buy a
second-hand Merida Magnesium Elite MTB that weighs in at only 9 kgs. I'm only a 70 kg. guy myself
so I'm not too worried about breaking this bike or anything.

Or should I? Some people claim magnesium is not very strong in comparison to aluminium or steel.
Is this true or only something "they" say?

Quoted message said:

Marten Hoffmann said:

In the past, Kirk made bicycles out of magnesium. Nowadays, only Merida makes them. I can buy a
second-hand Merida Magnesium Elite MTB that weighs in at only 9 kgs. I'm only a 70 kg. guy
myself so I'm not too worried about breaking this bike or anything.

Or should I? Some people claim magnesium is not very strong in comparison to aluminium or steel.
Is this true or only something "they" say?

The new top-of-the-range Pinarello Dogma is made of magnesium. It uses Dedacciai's AK61
Magnesium tubeset.

Magnesium is very light and has the durability of thick walled aluminium. Its a material with no
downside except maybe corrosion - it has a habit of developing blotchy green and black acne. You
have to made sure that the frame has been given the appropriate anti-corrosion treatment - then
you're on a winner

Rik O'Shea said:

Quoted message said:

Marten Hoffmann said:

In the past, Kirk made bicycles out of magnesium. Nowadays, only Merida makes them. I can buy
a second-hand Merida Magnesium Elite MTB that weighs in at only 9 kgs. I'm only a 70 kg. guy
myself so I'm not too worried about breaking this bike or anything.

Or should I? Some people claim magnesium is not very strong in comparison to aluminium or
steel. Is this true or only something "they" say?

The new top-of-the-range Pinarello Dogma is made of magnesium. It uses Dedacciai's AK61 Magnesium
tubeset.

Magnesium is very light and has the durability of thick walled aluminium. Its a material with no
downside except maybe corrosion - it has a habit of developing blotchy green and black acne. You
have to made sure that the frame has been given the appropriate anti-corrosion treatment - then
you're on a winner

Magnesium is quite low in the galvanic series. That makes it typically a sacrificial anode. Good
stuff for water heaters.

"Rik O'Shea" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Magnesium is very light and has the durability of thick walled aluminium. Its a material with no
downside except maybe corrosion

endurance limit?

failure modes?

Seems steel is better in both...

Also, if pure enough, magnesium makes a great fire:eek:

gwhite gwhite@hocuspocus_ti.com said:

Rik O'Shea said:

Quoted message said:

Marten Hoffmann wrote:

> In the past, Kirk made bicycles out of magnesium. Nowadays, only Merida makes them. I can buy
> a second-hand Merida Magnesium Elite MTB that weighs in at only 9 kgs. I'm only a 70 kg. guy
> myself so I'm not too worried about breaking this bike or anything.
>
> Or should I? Some people claim magnesium is not very strong in comparison to aluminium or
> steel. Is this true or only something "they" say?
>

The new top-of-the-range Pinarello Dogma is made of magnesium. It uses Dedacciai's AK61 Magnesium
tubeset.

Magnesium is very light and has the durability of thick walled aluminium. Its a material with no
downside except maybe corrosion - it has a habit of developing blotchy green and black acne. You
have to made sure that the frame has been given the appropriate anti-corrosion treatment - then
you're on a winner

Magnesium is quite low in the galvanic series. That makes it typically a sacrificial anode. Good
stuff for water heaters.

ANd definitely needs some sort of treatment wherever it contacts another metal... copper grease or
teflon tape for preference...

For what it is worth though I have to ask.. IS this a Magnesium bike? or is it another version of
"scandium" ie. simply an Aluminum bike with a different alloying element? I searched around a bit
and of the few english sites I found none were really clear.

I can't help but think of the "Huffy Titanium" and "Huffy Aluminum" ..not a description just a name.

Stellite <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Also, if pure enough, magnesium makes a great fire:eek:

Yeah, can you imagine a nice long slide out in a corner of a crit or even a descent. Now race
organizers would have to make sure that they have a haz-mat team in place to handle the risk of a
magnesium fire.
🙂
Would that mean that magnesium bikes are going to have carry the DOT Flammable solids placard when
they are on public roads? hmmm.........

[email hidden] schreef ...

Quoted message said:

ANd definitely needs some sort of treatment wherever it contacts another metal... copper grease or
teflon tape for preference...

For what it is worth though I have to ask.. IS this a Magnesium bike? or is it another version of
"scandium" ie. simply an Aluminum bike with a different alloying element? I searched around a bit
and of the few english sites I found none were really clear.

I can't help but think of the "Huffy Titanium" and "Huffy Aluminum" ..not a description
just a name.

Since the Merida Magnesium Elite really weighs in at some 9 kilos (in the smallest size, of course)
I'd gather it's really magnesium.

That said, I got informed that a magnesium frame will corrode whenever it's being scratched (as any
metal would do, of course). But it seems you can't stop it from corroding after the first scratch,
however carefully you re-powdercoat or re-enamel the frame.

My source has quite some experience with Avid magnesium brakes (discontinued) breaking off at the
point where the brake cable rubbed the magnesium and with magnesium lower legs on sprung forks that
kept breaking after minor scratches.

So I'm getting a little less enthusiastic about this bike ......

--
Regards, Marten

Quoted message said:

endurance limit?

most high tensile steels don't have an endurance limit.

If your mountain bike has a suspension fork, chances are its lower legs (and arch) are made from
magnesium. How does that make you feel? Does your friend have experience snapping forks too?

Or to put it another way, perhaps the Avid brakes were a bad design.

-Dion

"Marten Hoffmann" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

[email hidden] schreef ...

Quoted message said:

ANd definitely needs some sort of treatment wherever it contacts another metal... copper grease
or teflon tape for preference...

For what it is worth though I have to ask.. IS this a Magnesium bike? or is it another version
of "scandium" ie. simply an Aluminum bike with a different alloying element? I searched around a
bit and of the few english sites I found none were really clear.

I can't help but think of the "Huffy Titanium" and "Huffy Aluminum" ..not a description just
a name.

Since the Merida Magnesium Elite really weighs in at some 9 kilos (in the smallest size, of
course) I'd gather it's really magnesium.

That said, I got informed that a magnesium frame will corrode whenever it's being scratched (as
any metal would do, of course). But it seems you can't stop it from corroding after the first
scratch, however carefully you re-powdercoat or re-enamel the frame.

My source has quite some experience with Avid magnesium brakes (discontinued) breaking off at the
point where the brake cable rubbed the magnesium and with magnesium lower legs on sprung forks
that kept breaking after minor scratches.

So I'm getting a little less enthusiastic about this bike ......

[email hidden] schreef ...

Quoted message said:

If your mountain bike has a suspension fork, chances are its lower legs (and arch) are made from
magnesium. How does that make you feel? Does your friend have experience snapping forks too?

Yes he did. He sold these forks in his shop and nowadays he runs a bicycle assembly company.

Quoted message said:

Or to put it another way, perhaps the Avid brakes were a bad design.

Perhaps they were.

--
Regards, Marten