Road Cycling - Is Aluminum stronger than Steel?

I know there are different types of aluminum and steel, but in general, which is stronger?

I'm about 215 lbs. now, but hope to be 190 lbs. by the end of September (through lots of bicycling... I was 240 lbs. when I started this winter).

When I get my next road bike I'm going to get either aluminum or steel, but still am not sure which I should go with. I want something that will be strong and fast, mainly for exercise. I'm definitely not planning on entering races, but I might do some centuries once I drop some more weight.

Are the steel frame Bianchis good bikes (like the Veloce, Eros)... how about the Specialized Allez Cr-Mo? Or should I stick with a something like the Allez Comp with the double-butted aluminum frame?

Steel is always stronger than aluminum from a yield and ultimate strength perspective. For cycling, specific strength (strength per unit weight) brings them closer in peformance. To get aluminum stronger it's drawn and heat treated which makes it stiffer so it often rides harsher.
The bottom line is if the frame designer uses the material well you get a stiff frame which doesn't knock your teeth out. I ride a Felt f30 which is aluminum and carbon rides great and accelerates like a rocket. I'm 6'2" and 218lbs.I'd go steel or alum/carbon but not all aluminum.

Larry

Well steel is far stronger then aluminum. But as Larry pointed out, on a weight basis, aluminum compares favorably with steel.

If you look at an aluminum bike frame vs a steel bike frame, you will notice that the aluminum bike has larger diameter tubing then the steel bike. If you run aluminum in normal sized tubes, the frame will not be stiff enough. When you increase the diameter of the tubes, the frame gets much stiffer.

When aluminum bike frames first were put in use, they kind of over did it. These "over built" frames tended to be very strong and very stiff. Since then, aluminum frames have been made more compliant and probably less strong. Also, some manufacturers tend to emphasize different things so two aluminum framed bikes made by different manufactures could behave quite differently.

In your case, you are heavy but not REALLY heavy. I think any bike frame that is not "stupid light" (made as light as possible even at the expense of durability) would work just fine for you.

Different bikes have different handling characteristics based on geometry, construction and somewhat on materials. Going out and giving various bikes a test ride is about as good a way to judge them as any and better then most. Ride what you like.

http://www2.sjsu.edu/orgs/asmtms/artcle/articl.htm

Doesn't matter. If you take a thread with an equal cross section of material, the steel thread will be stronger. If you make up threads that have equal weight, the aluminum thread will be thicker and stronger. It's symplistic to narrow your thinking to the basic metal used.

You aren't buying steel or aluminum, you're buying a bicycle frame that is made from those materials. The frame manufacturer has lots of options concerning the basic material, the particular alloy of that material, the size and confirmation of the tubes, and the joining method. The frame manufacturer is going to make choices that exploit the advantages of the materials they use to produce a product they think will sell well.

When aluminum bike frames first were put in use, they kind of over did it. These "over built" frames tended to be very strong and very stiff.

Actually, the opposite is true and that kind of proves the whole point. Among the early aluminum framed bikes were offerings from Vitus and Alan. They were made from tubes that were sized to mimic bikes with steel tubesets. They were very light and very noodly. Gary Klein's original fat tube frame concept was to produce a bike that would weigh about the same yet be stiffer than the steel bikes of the day. The design was revolutionary at the time.

Hey Pat, thanks for your input, it was very helpful and thanks DnvrFox for the link to Bicycle Metallurgy!

thanks DnvrFox for the link to Bicycle Metallurgy!

You are welcome. It clarifies a lot of "myths" that seem to never end!

[QUOTE=ultra-g]I know there are different types of aluminum and steel, but in general, which is stronger?

I'm about 215 lbs. now, but hope to be 190 lbs. by the end of September (through lots of bicycling... I was 240 lbs. when I started this winter).

QUOTE]
in the winter I put the weight on, up to apx 240 and in the summer I get down to apx 195lbs
I ride a Bianchi Giro which is aluminum, and its a great smooth, strong ride.. :)

if you compare tensile-strength to weight ratio, then Aluminum is much stronger.. I guess thats why they make planes out of it.. :)

But strength and weight are not the only things that make a bike great. I believe that overall, steel makes better bikes.. How much better? Ill let you know when I get my steel bike in a month or so.. :D

The site about metallurgy has holes in it's research that many top frame builders and VeloNews disputes; also that research site does not build bikes so they have no real world experience.

The following information is from: Pure Opinions On Bikes, Materials, and Fitting; See the book: Hayduk, Douglas. Bicycle Metallurgy for the Cyclist. Boulder, Colorado 80302: Douglas Hayduk, 640 Marine Street, 1987.

This is written for relative bike rookies, re-entry riders, and folks who have managed to ride bikes for a while without learning much about them (which is fine, by the way). These are opinions based on my experience. You are free to disagree, but I don’t have time to debate. You’re lucky if you do!
Frames Materials
Chome-moly steel is the best material for bicycle frames, because it’s the safest and most durable (has a long fatigue life), is easiest to repair, and is more workable in the sense that in the right hands, it can be made more beautiful and unique. In the wrong hands, it’s still safer and more durable. Also, its strength and stiffness allow it to be used in diameters which are not just aesthetically pleasing, but also allow for good tire clearance, fender clearance, and so on. If the tube has to be fat to be strong, it encroaches on the tire too much; steel doesn’t. Don’t fear rusting steel—there are a number of sprays you can coat the insides of the tubes with to absolutely prevent rust; so don’t worry.
Aluminum is light and cheap and always large-diameter because, like a presto log or a block of pink popcorn, it doesn’t stand up to repeated flexing. Aluminum has a short fatigue life, so the smarter makers eliminate fatigue-inducing flex by using huge diameter tubes. There are some fine aluminum frames out there—notably, the ones made by Charlie Cunningham and Gary Klein. They at least, have some flesh and blood and brains behind them. But today’s cheap-labor imitations have nothing to offer beyond their function, and if you can warm up to one of them, you can likely warm up to anything. Consider yourself lucky?

The following info is from: VeloNews dated 6/10/03, page 42.

“As anyone familiar with beer cans can tell you, al is softer and less stiff than steel. Al is easy to draw and form into shapes, easy to machine and relatively easy to weld. Its density is about a third of steel and half of ti, so it is not hard to build a light bike with it. It will oxidize, and should be painted, powdered coated or anodized to prevent corrosion, but it does not rust away rapidly. Al has downsides too. Its tensile strength, yield strength and elongation are far less than those of high strength steel and ti alloys. Al is more vulnerable in a crash. Al has no fatigue limit, a property steel possesses, often expressed as a % of its tensile strength. Below this limit, the material can be cycled indefinitely without breaking. This means that al can be less predictable than steel as to when it will fail after long use. Back to our beer can: compare a can of beer to a metal can of olives and it’s apparent that he al container has much less stiffness than a steel can of similar thickness and diameter. Yet many al bikes feel stiff. Why? It’s because al’s density is so low; tubes can be made large and thick for stiffness and light weight. Al can be alloyed with other elements to enhance its properties. Scandium for instance is an element that can help make a very strong al alloy. “

Titanium is a wonderful material with enviable properties, but it still isn’t as stiff as steel, so you have to use it in larger diameters. So Ti chain stays have two choices: crowd the tire or crowd the chain rings. For the same reason, Ti fork blades are used rarely, and only in large-cross sections, which look terrible on road bikes, and only barely acceptable on any bike. Titanium is not as tough as steel is, so cracks in it tend to propagate faster, leading to earlier failure. And then, it’s harder to repair.
Titanium has been sold as a near magical material, but its biggest deal is that it won’t rust. And that's no big deal!
Carbon fiber is a most remarkable material that is not living up to its promise. It’s light, yes. It’s strong when it’s new. But carbon fiber is sort of like a heavyweight boxer with a great right cross and left hook, who is also a hemophiliac and can’t take a punch. It loses its strength and so much of its safety when it gets chipped, knicked, weathered, and generally beat around as a bicycle gets beat around. Carbon fiber forks are famous, at least among manufacturers and distributors, for snapping instantly, and this in spite of the fact that it’s virtually impossible to buy an off-the-shelf high-end bike without a carbon fork. Whether you like the looks of a carbon fiber frame, is another issue altogether. Summary: Light, strong in the lab, but with a track record of sudden failures.

Then there are these web sites:

http://www.henryjames.com/faq.html
http://www.kirkframeworks.com/Philosophy.htm
http://www.exploratorium.edu/cycling/frames1.html
http://www.roadbikerider.com/UArant3.htm#Frame%20Materials%20for%20Big%20Guys
http://rivendellbicycles.com/html/101_pureopinions.html
http://rivendellbicycles.com/html/101_framematerials.html

As you can now see there is always 2 sides to every piece of balony!

Whether you like the looks of a carbon fiber frame, is another issue altogether. Summary: Light, strong in the lab, but with a track record of sudden failures.

Then there are these web sites:

http://www.henryjames.com/faq.html
http://www.kirkframeworks.com/Philosophy.htm
http://www.exploratorium.edu/cycling/frames1.html
http://www.roadbikerider.com/UArant...or%20Big%20Guys
http://rivendellbicycles.com/html/101_pureopinions.html
http://rivendellbicycles.com/html/1...ematerials.html

As you can now see there is always 2 sides to every piece of balony!


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84 Trek 660 Suntour Superbe
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Hey, thanks for the comments and additional web sites. Nice to know there is controversy even amongst engineering types.

They all work...
use the bike you like the most.
Avoid potholes.
have fun ;)

even i'd buy an aluminum cervelo soloist team if i could. just get the bike you like. unless your doing lots of touring. then go with steel.

I have always owned aluminum bikes, except for my first bike, and probably will never change. I believe that aluminum, so far, is the best ride for me. The stiffness doesnt "rattle my teeth" and I love the handling through steep fast turns. So I would agree with one of the posters above. Ride to feel whats best for you. Everyone has their own opinions and that doesnt make it yours.

hey, do what I did, get one of each..:)