Magnesium frames any good?

[bsyptak]

I've been eyeing a magnesium MTB frame on Ebay. 2.8 lbs. For $110, it seems worth a try. That is unless it's unsafe. Thoughts? The only thing I've seen is that they are tough to paint & may oxidize. I'm in dry climate so it doesn't matter.

Thx.

[Thylacine]

I think you'll find they're an Aluminium alloyed with Magnesium, and if a multi-national bicycle company decides to make thousands of frames out of somthing, i think it's safe to say they won't spontaneously combust.

Whether it rides nicely or actually fits you is another matter.

[ranger5oh]

Its not solid Magnesium... not for $110. Its also not solid mag for the fact it would combust on a humid day.

Its prolly a POS.

[Falanx]

Its not solid Magnesium... not for $110. Its also not solid mag for the fact it would combust on a humid day.

Its prolly a POS.

I should imagine there are Kirks left in circulation. But Dawes stopped selling them due to the actions of a lecturer at my University's Materials department. By God, they were a POS. Pores, inclusions, finger-sized voids...

Combust in humidity, eh? You might want to speak to ductile iron manufacturers up and down the country. They tend to stockpile solid magnesium in vast quantities and are daily plagued by it not spontaneously catching fire. It may hydrolyse. But even then, not below about 300 degrees.

[rmfnla]

Hold onto your butts...

Magnesium, like aluminum, has poor dynamic qualities and is an unsuitable material for a bike frame.

There, I said it!

[2manybikes]

Hold onto your butts...

Magnesium, like aluminum, has poor dynamic qualities and is an unsuitable material for a bike frame.

There, I said it!

Oh no ! Here we go............

[Falanx]

Hold onto your butts...

Magnesium, like aluminum, has poor dynamic qualities and is an unsuitable material for a bike frame.

There, I said it!


Troll -1.

:)

Dyanamic? Dynamic? What, you mean a lump doesn't move very much of it's own accord?

[zonatandem]

A magnesium Paketa tandem won this year's Hotter Than Hell 100 in TX.
Don't knock a material unless you have used it . . .

[Falanx]

My issues with magnesium alloys as bicycle materials stem from;

Mechanical: It's a hexagonal metal with a long c/a ratio so it doesn't have many active slips systems and exhibits low ductility. Ductility is a consequence of work hardening and the difference between UTS and yield (contrary to the popular belief that UTS is determined by ductility). Therefore, it is also brittle.

Chemical: It's grossly reactive, and its oxide is water soluble and reactive. The oxide lattice-matches well and is stable, but forms hydroxide readily with water.

Metallurgical: The only 'safe' - the weld has acceptable strength and toughness - welding for magnesium is friction stir welding, a process utterly unsuited for bicycle frames that are tubular. Aluminium welds are inherently unsafe themselves. But magnesium is aluminium to the nth degree.

[ken cummings]

I would doubt the value of a $110.00 frame when a good set of wheels costs a lot more. I rode a Kirk die-cast magnesium bike when they first came out and it was a nice bike. I would give a lot just to have a Kirk frame clear-coated and mounted over my fire place. The I-beam construction (not glued tubes) is one of the sexiest thing I have ever seen.

[Pride81]

I was going to mention that, but you beat me to it. Here's a website to where the magnesium tandem can be
found http://www.precisiontandems.com/catframetandem.htm

[Pride81]

Try this link http://www.paketa.com/tandems.htm

[rmfnla]

I would doubt the value of a $110.00 frame when a good set of wheels costs a lot more. I rode a Kirk die-cast magnesium bike when they first came out and it was a nice bike. I would give a lot just to have a Kirk frame clear-coated and mounted over my fire place. The I-beam construction (not glued tubes) is one of the sexiest thing I have ever seen.


I remember those.

Are you sure you would want it so close to an open flame..?

[2manybikes]

I remember those.

Are you sure you would want it so close to an open flame..?

:lol:

If you need to make a campfire all you need is a knife and a flint !

[Peterpan1]

Bow risers used always to be made of powder coated magnesium alloy. For some reason cast aluminum never made it until the CNC process became cheap enough to mill billet aluminum.

[slowandsteady]

To heck with magnesium, go with Sodium, not sodium chloride. Pure sodium. It would explode if it got wet. Nice!

[rmfnla]

Troll -1.

:)



What does that mean?

[kiperto]

I ride a magnesium frame on my road bike, a Litech made by some former Soviet aerospace engineers. I do not know if they are still around. It's a great. Being my first roadie in 10 years I only have a steel Giant from my high school days to compare it to.

1) It has not spontaneously combusted on me yet.
2) Okinawa is pretty humid and we got a steady month of rain in May-Jun. No signs of corrosion.
3) The frame is very light and very responsive. Again I do not have much to campare it to but for $110 I'd say you cannot go wrong with that mountain bike frame.

And it could be one of those Litech frames. I bought mine off a friend who lived in Kazakhstan when he first discovered them. He bought two, rides one and sold me the other. I paid about $500 for my frm from him. He probably bought it for about $350-$400 or so direct from the manufacturer.

[poopncow]

My issues with magnesium alloys as bicycle materials stem from;

Mechanical: It's a hexagonal metal with a long c/a ratio so it doesn't have many active slips systems and exhibits low ductility. Ductility is a consequence of work hardening and the difference between UTS and yield (contrary to the popular belief that UTS is determined by ductility). Therefore, it is also brittle.

Chemical: It's grossly reactive, and its oxide is water soluble and reactive. The oxide lattice-matches well and is stable, but forms hydroxide readily with water.

Metallurgical: The only 'safe' - the weld has acceptable strength and toughness - welding for magnesium is friction stir welding, a process utterly unsuited for bicycle frames that are tubular. Aluminium welds are inherently unsafe themselves. But magnesium is aluminium to the nth degree.

++ bloke,
but there is something to be said about pearls and porcines,
where heresay wins over reason.
where branding and marketing stomps science and sound design
cheers!

[bikejoel]

i have one of the litech mtn bike frames. the frame cracked where the seat tube extends above the top tube. you need to use the proper seat post shim with a 31mm OD not the 30.9 OD the seller has listed
i double shimmed (stacked) the replacement frame and have not had any problems since. the bike weighs in at 23 lbs and i weigh 200lbs

[bsyptak]

I love it when my threads pop up a year later.

[Revtor]

http://www.mgbiker.20m.com/index.htm

these are the frames. the site is kinda dodgy and hasn't been updated in a few years, but the info is there.

the frames are extruded tubing, a combo of ovalized and round, welded beautifully. the alloy is 94% magnesium and the metal is derived from saltwater! supposedly they worked on the manufacturing, alloying, extruding and welding for a long time. only one or two groups in the world have worked this all out.. the litech guys and a South African company who now supplies Paketa.
People are resistant to new things, and without a slick marketing campain, one or two companies surely aren't going to make much of a splash in a market that is filled with highly engineered marvels like 853 steel, hydroformed aluminum, and exotic monocoque CF. Unless this magnesium frame was ALOT better in some regard, or the company had the marketing department to make people believe it was, the MG frame will remain an obscure novelty. They almost made it big time when Specialized almost picked up Litech Magnesium frames for their s-works M5 line (mtb) but the project wax nixed becasue of cable routing issues!! yes... a shame. its good to hear that specialized has their eyes open for new technology at least!!

I got a 54cm road frame two weeks ago from a guy who imported and rebadged/painted these litechs a few years ago. (got it on ebay) its very light, the welds are perfect, and it comes with a gold coating that prevents corrosion. I got mine powdercoated clear just recently and have almost everything I need to build it up..

the frames are constructed very well I can tell you that. as for the ride, I cant say yet. all reviews seem to be positive, but most bike reviews are.

anyone else with real experience abord one of these?

ill bump the thread with any info once the machine is rideable!

~Steve

[seeker333]

Easton made some Mg stems a few years back, coating peeled off and they rusted like crazy. So look out for scratches, paint peel.

The lowers of many suspension forks are made from magnesium - they're diecast with no welds.

Seems like your frame oughta work fine if joints are good.

Of course there's a lot of inexpensive Al mtb frames available that weigh in under 4 pounds.

[Dr.Deltron]

Aquired this beauty recently. The only thing a magnet sticks to are the bolts! :p
The frame tubes are magnesium, but I'm not sure how many of the other non-magnetic parts are.
There are no welds, just clamps & rivets.

[bikejoel]

Looks like you're ready to enter a HPV (Human Powered Vehicle) competition. I've seen bikes like this before in these competitions. i'm assuming it's a "rear steer" how is that for cornering? nice ride!

[palmtree]

Any more information on the Mg frames?

[Dr.Deltron]

Looks like you're ready to enter a HPV (Human Powered Vehicle) competition. I've seen bikes like this before in these competitions. i'm assuming it's a "rear steer" how is that for cornering? nice ride!

I am ready, but NOT on this trike! :p
I have a Greenspeed GTX thats a better "racing" trike, or a Challenge Hurricane for 2 wheeled, high speed fun!

The Thebis IS rear steer! It is NOT made for cornering! :p
It's biggest "plus" is the "WOW! What IS that? I've never seen one of those before!" factor. :rolleyes:
But it's all original and in very nice shape. Thanks for the compliment! :D

[abbynemmy]

I'm surprised no one mentioned the Pinarello Dogma.

http://www.competitivecyclist.com/za/CCY?PAGE=PRODUCT&PRODUCT.ID=3669

[DasProfezzional]

I was going to bring up the Ellsworth MGnificent, but a visit to their page revealed that it has apparently been discontinued. Hm.