Road Bike, Cycling Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
354 Posts
Discussion Starter #1
Over on a Cyclingnews interview, I read somewhere (paraphrased) "the bike envelope can still be pushed: bike manufacturers are building strong, stiff, sub 1kg carbon bikes, and are now beginning to experiement with magnesium. Bicycle innovation has not peaked yet".

So, is magnesium the next level in performance? The Dogma is the only magnesium frame I am aware of-are there others? If so, are they a step above carbon? The Dogma isn't exactly lighter than a carbon frame (it is about 1250g frame only, whereas as many carbon frames are 1100g or under) and seems to be a bit smoother than the typical alloy bike at the same stiffness, but not as smooth as a well-done carbon frame. Is there more promising magnesium frames or components on the way, ones that will eventually replace carbon fiber? Ski manufacturuers have begun replacing titanium in their skis with magnesium alloys, on certain race models.
 

·
Resident Dutchbag
Joined
·
11,864 Posts
There's a few more companies that make magnesium frames. My impression was that magnesium is a material that is not going to really break through because frames couldn't be made as light as carbon frames while at the same time being more expensive as aluminum, but I could be wrong.
http://www.magnesium.com/w3/uses/index.php?cat=10&product=1028
 

·
Registered
Joined
·
168 Posts
In thinking about magnesium frames, I would consider the difficulty that American Classic has apparently had producing a magnesium rim that's market-ready. When it was first announced, I think they called it the "Mg 300" or something like that, but at least a year after they announced it, they were advertising it as 325 grams. That's pretty close to the weight of their aluminum rim, the CR350, which is actually weighing in at 360-some grams.

One of the problems, I think, is that magnesium is exceptionally suceptible to oxidation (rusting). In fact, Mg has the highest reduction potential of any structural metal - to the tune of 0.7 volts more than aluminum, which itself oxidizes more readily than iron (steel). Aluminum can get away with oxidation because Al2O3 (aka corundum, sapphire) is a durable coating that prevents further oxidation. Oxides of iron and magnesium don't provide similar protection. Magnesium alloys are anothre matter, but IIRC, pure Mg is quite suceptible to etching and pitting.

AmClassic hints at the difficulty of using Mg on their web site; they call their wheels "The ultimate clincher wheelset for race or event use only," and describe their rustproofing method as "Ceramic coating with an epoxy seal for durability and to fight corrosion. Ceramic braking surface. Magnesium wheels require more care than other rims." For them, Mg is an alternative to carbon because you can make a clincher out of it. For the shapes of a bicycle frame, though, carbon is already pretty close to ideal.
 

·
Registered
Joined
·
432 Posts
http://www2.sjsu.edu/orgs/asmtms/artcle/articl.htm

Always, when talking about a particular material to use for making a bicycle, I would re-read this series of articles. I have not re-read through completely but I recall there was a bit in there that discussed magnesium. I think the bottom line is that there are serious cons to using magnesium as a frame material in the real world. Corrosion is one that was touched upon. Besides the charateristics of the material itself, other factors come into play, like cost being a big one. Assuming the cons of magnesium could be overcome, the cost of the material or processing of it could be cost-prohibitive. In the free market what you pay for has to give back something in some kind of value, even if it is only in bling. After all we buy perfume, jewelery and fine wines.
 

·
imbasilical moreon
Joined
·
1,873 Posts
likeguymontag said:
In thinking about magnesium frames, I would consider the difficulty that American Classic has apparently had producing a magnesium rim that's market-ready. When it was first announced, I think they called it the "Mg 300" or something like that, but at least a year after they announced it, they were advertising it as 325 grams. That's pretty close to the weight of their aluminum rim, the CR350, which is actually weighing in at 360-some grams.

One of the problems, I think, is that magnesium is exceptionally suceptible to oxidation (rusting). In fact, Mg has the highest reduction potential of any structural metal - to the tune of 0.7 volts more than aluminum, which itself oxidizes more readily than iron (steel). Aluminum can get away with oxidation because Al2O3 (aka corundum, sapphire) is a durable coating that prevents further oxidation. Oxides of iron and magnesium don't provide similar protection. Magnesium alloys are anothre matter, but IIRC, pure Mg is quite suceptible to etching and pitting.

AmClassic hints at the difficulty of using Mg on their web site; they call their wheels "The ultimate clincher wheelset for race or event use only," and describe their rustproofing method as "Ceramic coating with an epoxy seal for durability and to fight corrosion. Ceramic braking surface. Magnesium wheels require more care than other rims." For them, Mg is an alternative to carbon because you can make a clincher out of it. For the shapes of a bicycle frame, though, carbon is already pretty close to ideal.
Leonard Zinn is doing custom mag bikes......here.....I noticed they are painted, for corrosion protection?
 

·
Registered
Joined
·
432 Posts
Being that magnesium has the same down side as aluminum, being there is no fatigue limit, meaning that the slightest flex eventually will cause the metal to fail. So, although it's lighter than titanium it's got to be built up like aluminum bikes. I don't see an advantage. I'd rather go with steel or carbon fiber for a frame that does not fail do to fatigue as long as there was no crash that exceeded the fatigue limit of the material.
 

·
Banned
Joined
·
476 Posts
steel maybe the long term 'replacement' for carbon

everything that goes around, comes around

steel lasts longer than any other material and the ride is hard to argue with

maybe when lots of carbon frames have to be replaced due to cracks, tar or solvents, or minor 'slip ups' [like chain suck] ; many riders may deside to swing back to a mareial that is more durable
 
1 - 9 of 9 Posts
Top