Is Magnesium Real......Huh?

[greatwhite]

If magnesium could be built lighter and as stiff as carbon, more would have been around. The key indicators of a frame material would be specific stiffness (stiffness/density) and specific strength (strength/density). Cabon is just so vasly superior as an engineering material that it makes no sense to develop alternatives that will not be as good. Laminate properties for top end carbon is hard to believe - if I remember correctly : 2000 GPa Young's modulus and 4000 MPa ultimate tensile stress - black magic ingeed.

Back to magnesium; Mg needs special care to work with. While it is a misconception that a mg component would burn at the slightest exposure to fire, this is true of shavings from machining and filing etc.

It also corrodes when exposed to chlorides - salt water & sweat.

In general I think the development effort outweighs potential benefits.

I do not agree wrt the OP's statement about custom carbon being simplistic. Some companies like Parlee, Cyfac and Sarto make carbon frames that is cuatomized in all regards - custom geometry, custom layup, custom tube thickness. The top companies effectively offer custom ride quality.

I cannot for the life of me understand why anybody would spend R100k or more on a frame that is mass produced in China and lots of very near copies could be bought for R5000 a pop, if a bespoke frame could be had for the same money.

In that lies one of the attraction for metal frames imo - there are no cheap chinese copies. The metal frame may be heavier than carbon, but would 500g more make a difference to 95% plus of riders at an event? I dont think so - most ride to finish, not to podium.

Nice reply.

Regards carbon fibre: I don't know that ultra high modulus carbon gets quite as high as 2000GPa Youngs modulus, but maybe you have seen new data I haven't. Compared to other materials though, I guess I am just knit picking anyway. What I do anticipate is that strength will increase a long way too. Research shows carbon nanotechnology tubes failing at 63GPa as an indication of where things could go. Generally though, though bikes are not made from these super exotic carbon fibres, nor in many instances would you want too. You do need a little compliance otherwise your bike will be like riding an anvil.... and they are insanely expensive.

 

With regard to simplistic carbon frames, you actually made my point. If you look at the Parlee custom frames they are essentially tubes and lugs. While they can lay extra/different material to customize, what they can't do is have a custom shape. This gives the mass produced frame the advantage in outright performance. The same appears to be the case for the sarto frames too (notice the consistent tube sections). Cyfac impress me more, at least they have varying tube sections, but guessing by the shape of the tube junctions, they are still lugged albeit nicely done. A person that reasonably closely matched the mass produced frame is probably better of with such IMO. As to why people spend so much on a mass produced frame - I guess they are victims of marketing (I know I have been on occasion and I tend to cynical of marketing bs.), availability & ignorance (of these niche manufacturers)

 

Back to magnesium: if it became as easy to make a magnesium frame as say steel. Do you think the would be uptake?

[HeyYou]

My magnesium Kirk.

 

But, it's heavy and a little noodely. But it is 30 odd year old tech. Mine is an early edition, with a steel fork, later models had an ali fork and I believe a carbon fork makes it even better. I live at the coast and some oxidising, but I've seen a lot worse 20 year old steel frames. 

 

I have steel, ali, lugged carbon and carbon bikes. For a +100 km ride I like my carbon Tommasini the best. It's hand made in Italy, around 2007, so maybe it's a little more compliant than a modern monocoque frame.

 

 

[greatwhite]

My magnesium Kirk.

 

But, it's heavy and a little noodely. But it is 30 odd year old tech. Mine is an early edition, with a steel fork, later models had an ali fork and I believe a carbon fork makes it even better. I live at the coast and some oxidising, but I've seen a lot worse 20 year old steel frames.

 

I have steel, ali, lugged carbon and carbon bikes. For a +100 km ride I like my carbon Tommasini the best. It's hand made in Italy, around 2007, so maybe it's a little more compliant than a modern monocoque frame.

Awesome - thanks for response. You say it's heavy and noodley, but does it soak up vibration well? (seems to one of the common threads on overseas forums for newer Mg frames)

 

Are you aware of anymore of these bikes in SA?

[HeyYou]

Awesome - thanks for response. You say it's heavy and noodley, but does it soak up vibration well? (seems to one of the common threads on overseas forums for newer Mg frames)

 

Are you aware of anymore of these bikes in SA?

 

Yes, it's a compliant ride, but my guess it has more to do with the frame design and geometry than with the Mg. 

 

It feels a bit like a lugged ali frame, Vitus, or Alan, perhaps a little stiffer.

 

There should be a couple of these in SA, they were pretty rad in the mid to late 80s. I remember seeing a few of them (I was riding a Hansom Super Prestige, 531c), though they were uncommon. One was sold on the Hub a couple of months ago, so there's at least 1 more somewhere in SA!!!

[seanp]

I think HeyYou is referring to mine. Purchased it from a fellow Hubber in November last year. Have to admit it was a spontaneous buy. Seen pics and read the articles about the Kirk before, but never actually seen one in the flesh. Just thought it looked so damn cool, and took the plunge. Remember it arriving from Jhb on a Thursday. So eager to get it home and check it out properly. Spent 2 hours that evening just giving it a good clean - bit of grime that had obviously accumulated over a lengthy period of none-use. Took it to the spray painter the following week. Been there since. No huge hurry to get it back yet - project for later this year.

Also heard that it had similar ride characteristics to the Vitus 979 and Bridgestone Radac alu bonded frames.

[Stretched@Birth]

I think HeyYou is referring to mine. Purchased it from a fellow Hubber in November last year. Have to admit it was a spontaneous buy. Seen pics and read the articles about the Kirk before, but never actually seen one in the flesh. Just thought it looked so damn cool, and took the plunge. Remember it arriving from Jhb on a Thursday. So eager to get it home and check it out properly. Spent 2 hours that evening just giving it a good clean - bit of grime that had obviously accumulated over a lengthy period of none-use. Took it to the spray painter the following week. Been there since. No huge hurry to get it back yet - project for later this year.

Also heard that it had similar ride characteristics to the Vitus 979 and Bridgestone Radac alu bonded frames.

If I'm not mistaken, Simon Kessler raced one of these for a short period I. The late 80's/early 90's.

[eddy]

If you want to ride your Mag around the Zoo Lake on a Sunday morning you will need to paint it gold.

[olffie1]

Leave magnesium for garden furniture!

[greatwhite]

Leave magnesium for garden furniture!

Didn't even know they made garden furniture from it - learn something new everyday. I would have thought the manufacturing cost would have made it prohibitive, but to be fair I have very little experience with Mg casting. I certainly can't see someone saying 'my Mg garden chair is 150g lighter than our Al garden chair'

[V12man]

Didn't even know they made garden furniture from it - learn something new everyday. I would have thought the manufacturing cost would have made it prohibitive, but to be fair I have very little experience with Mg casting. I certainly can't see someone saying 'my Mg garden chair is 150g lighter than our Al garden chair'

They don't - it's zinc....

[SwissVan]

 

2 - corrodes in air...badly

 

 

This

I've worked with magnesium parts used on aircraft, and in my experience the only thing that is gaurenteed to happen is it will need to be replaced much sooner than parts made from traditional materials like aluminum, titanium or steel.

 

So if anyone wants a frame that you can chuck away every few years or will crack under you, go ahead and get a magnesium frame

[SwissVan]

Nice reply.

Regards carbon fibre: I don't know that ultra high modulus carbon gets quite as high as 2000GPa Youngs modulus, but maybe you have seen new data I haven't. Compared to other materials though, I guess I am just knit picking anyway. What I do anticipate is that strength will increase a long way too. Research shows carbon nanotechnology tubes failing at 63GPa as an indication of where things could go. Generally though, though bikes are not made from these super exotic carbon fibres, nor in many instances would you want too. You do need a little compliance otherwise your bike will be like riding an anvil.... and they are insanely expensive.

With regard to simplistic carbon frames, you actually made my point. If you look at the Parlee custom frames they are essentially tubes and lugs. While they can lay extra/different material to customize, what they can't do is have a custom shape. This gives the mass produced frame the advantage in outright performance. The same appears to be the case for the sarto frames too (notice the consistent tube sections). Cyfac impress me more, at least they have varying tube sections, but guessing by the shape of the tube junctions, they are still lugged albeit nicely done. A person that reasonably closely matched the mass produced frame is probably better of with such IMO. As to why people spend so much on a mass produced frame - I guess they are victims of marketing (I know I have been on occasion and I tend to cynical of marketing bs.), availability & ignorance (of these niche manufacturers)

Back to magnesium: if it became as easy to make a magnesium frame as say steel. Do you think the would be uptake?

2 telling letters forming a simple word in your and Christies posts

 

IF

 

and to add to the magnesium iffitius

 

IF magnesium did not corrode so easily

[SwissVan]

I think HeyYou is referring to mine. Purchased it from a fellow Hubber in November last year. Have to admit it was a spontaneous buy. Seen pics and read the articles about the Kirk before, but never actually seen one in the flesh. Just thought it looked so damn cool, and took the plunge. Remember it arriving from Jhb on a Thursday. So eager to get it home and check it out properly. Spent 2 hours that evening just giving it a good clean - bit of grime that had obviously accumulated over a lengthy period of none-use. Took it to the spray painter the following week. Been there since. No huge hurry to get it back yet - project for later this year.

Also heard that it had similar ride characteristics to the Vitus 979 and Bridgestone Radac alu bonded frames.

I suggest you remove the bolts and bits that are made from other metals that attach to the frame.... and look closely for corrosion pitting before you invest money in a paint job

[seanp]

I suggest you remove the bolts and bits that are made from other metals that attach to the frame.... and look closely for corrosion pitting before you invest money in a paint job

Hi SwissVan. Thanks for the advice. Actually stripped the frame of all metal parts - as in the pic - the same day I received it; prior to the clean. Can't say that I saw any obvious pitting, checked for the normal - cracks, fractures, that sort of thing. But since the eyes are not as great as before, i'Ll ask the spray painter to do another check before any further work is performed.

Hold thumbs that all is in order, otherwise I may be saddled with an expensive wall-mount.

 

Regards Sean

[SwissVan]

Hi SwissVan. Thanks for the advice. Actually stripped the frame of all metal parts - as in the pic - the same day I received it; prior to the clean. Can't say that I saw any obvious pitting, checked for the normal - cracks, fractures, that sort of thing. But since the eyes are not as great as before, i'Ll ask the spray painter to do another check before any further work is performed.

Hold thumbs that all is in order, otherwise I may be saddled with an expensive wall-mount.

Regards Sean

Hopefully I'm being over pessimistic... good luck and even in the worst case scenario you will have a frame that would look good hanging in your bar

[HeyYou]

Hopefully I'm being over pessimistic... good luck and even in the worst case scenario you will have a frame that would look good hanging in your bar

 

I'm certainly not a metallurgist, or any kind of ....gist, but I think you are being a little pessimistic. Mag wheels were all originally magnesium alloys and corrosion wasn't the problem with them, it was brittleness.

 

I don't know, but I'm sure these Kirk frames were magnesium alloy of some kind, so although they may be brittle, I don't think big time corrosion will be a problem. 

 

I certainly checked my Kirk frame, as I do all my frames, and besides a bit of surface oxidation, nada.

 

But then again, I won't be riding it downhill over cobbles!!!!