Grades of Aluminum

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I am trying to understand various types of Aluminum was they are used for bicycle parts. There's a 2014 aluminum used by Ritchie, 7000 by Thomson, 6061 by Dimension. I've never used Dimension before but have Thomson and Ritchie parts and am very pleased with them. Any opinions?
 
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Originally Posted By: whizbyu
I am trying to understand various types of Aluminum was they are used for bicycle parts. There's a 2014 aluminum used by Ritchie, 7000 by Thomson, 6061 by Dimension. I've never used Dimension before but have Thomson and Ritchie parts and am very pleased with them. Any opinions?
2014 is a copper alloy, medium high strength, good forging alloy. 6061 is a silicon alloy, all purpose medium strength, easy fabrication, best price/performance of the 3. 7000 is a zinc alloy, high strength alloy. Used a lot in aero-space applications. This is very general. Google the alloy number to get lots of info. Wayne
 
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Can't help with regard to the specifics of bike parts. The four digit designations controls the percentages of alloying elements. Letters and numbers that follow the four digits specify the temper. So in the case of 6061-T4 the "6061" designates the alloy composition, and the "T4" is the specifics of the temper. Never heard of 7000. Might be the "alloy" a manufacturer chooses to market their product under, as opposed to a true alloy number. Such practice is often used in the cutlery industry, where terms like "Surgical Steel", "Chrome vanadium", and "High Carbon" are used which, by themselves, specify very little. In many aluminum alloy applications, the temper is just as important as the alloy itself. In aerospace I see mostly 6061 and 7075 of various tempers. Sometimes an alloy's ease of machining or welding can influence the alloy chosen. Search "alluminum alloys" at wikipedia for more info.
 
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whizbyu

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Trying to understand why one is more expensive than the other. Specifically looking at different brands of stems for a mountain bike. Nothing daring like downhill runs or hucking; just trail riding on technical singletrack.
 

JTK

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I think we use 6-7K grade aluminums for cryo service at our plants. Right down to the -240C range for liquid hydrogen service.
 
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For Bicycle parts 7000 is usually more expensive than 6000 probably due to the fact it's more difficult to weld. When you read about the differences for mountain biking they are so insignificant as to make it moot. For road biking the best stuff is scandium allor or carbon, so I doubt it matters as much there either. So my opinion is it doesn't matter if you're not the one welding it.
 
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Originally Posted By: whizbyu
Trying to understand why one is more expensive than the other. Specifically looking at different brands of stems for a mountain bike. Nothing daring like downhill runs or hucking; just trail riding on technical singletrack.
If you don't really care about weight, just get one that looks semi-beefy. I went with a light duty DH one on my XC bike as that's one part I never want to fail...
 
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Originally Posted By: whizbyu
Trying to understand why one is more expensive than the other. Specifically looking at different brands of stems for a mountain bike. Nothing daring like downhill runs or hucking; just trail riding on technical singletrack.
You're on your own with that one... even if a person knew material properties forward and backward, (and I'm including processing methods, heat treatment, etc.) there are still things like brand prestige that add to the price the manufacturer feels justified in charging.
Originally Posted By: JTK
I think we use 6-7K grade aluminums for cryo service at our plants. Right down to the -240C range for liquid hydrogen service.
Yikes... LH2 service? Even at room temperature, I'd think that any metal in contact with that concentration of hydrogen would get brittle awfully fast.
 
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Another factor with aluminum is weld-ability. I have noticed the lower numbers weld better. Especially Tig. I normally use 4043 tig or mig for welding. Just sayin.
 
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The most popular 7000-series alloy is 7075, which is also about the strongest aluminum alloy that is readily available. But 7075 has problems with stress corrosion cracking in the T6 temper. It is also available in the T73 temper, which is less susceptible to SCC, but has slightly lower strength. Tensile strength of 7075-T6 is about 83 kpsi. If you want to avoid SCC, 7075-T73 has tensile strength of 73 kpsi. 6061-T6 is probably the most popular alloy for shops to make billet components from. Most of the time, when somebody is trying to sell you "aircraft aluminum", 6061-T6 is what they're talking about. Tensile strength of 6061-T6 is about 45 kpsi. There are stronger 6000 aluminums, such as 6066 and 6070, but they are hard, if not impossible, to find. 2014-T6 I don't think is as readily available as the other two, but its tensile strength falls in between, at 70 kpsi. The 2000-series aluminums have better high-temperature strength than the 6000 & 7000's. But I don't expect you would need that on a bike. As far as corrosion resistance is concerned, 6000 series is better than the 2000 and 7000.
 
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Need more information than simply the material type. For example; 7000 series are alloyed with zinc, and CAN be precipitation hardened to the highest strengths of any aluminium alloy. http://en.wikipedia.org/wiki/Aluminium_alloy Yes, OK, but HAS it been precipitation hardened? 6061 Aluminum is the most common grade of STRUCTURAL Aluminum, and the easiest to repair should you ever need to do so. That being said, all of your choices sound like excellent quality materials, my opinion is it would come down to your personal preference, style, price. And 6061 Aluminum is commonly welded with 4043 wire, which is widely available. American Welding Society Certified Welding Inspector
 
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Originally Posted By: Ihatetochangeoil
Need more information than simply the material type. For example; 7000 series are alloyed with zinc, and CAN be precipitation hardened to the highest strengths of any aluminium alloy. http://en.wikipedia.org/wiki/Aluminium_alloy Yes, OK, but HAS it been precipitation hardened? 6061 Aluminum is the most common grade of STRUCTURAL Aluminum, and the easiest to repair should you ever need to do so. That being said, all of your choices sound like excellent quality materials, my opinion is it would come down to your personal preference, style, price. And 6061 Aluminum is commonly welded with 4043 wire, which is widely available. American Welding Society Certified Welding Inspector
Correct. 4043 alum wire(tig, mig) welds much better than 5000 series. I have used 4043 on various grades of aluminum.
 
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Originally Posted By: Ihatetochangeoil
Need more information than simply the material type. For example; 7000 series are alloyed with zinc, and CAN be precipitation hardened to the highest strengths of any aluminium alloy. http://en.wikipedia.org/wiki/Aluminium_alloy Yes, OK, but HAS it been precipitation hardened?
Yes, it has been precipation hardened. For the aluminum alloys that are heat-treatable, precipitation hardening is the prevalent method. T6 always means precipitation hardening.
 
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I'll admit that my understanding of various alum alloys is sadly lacking but I always was under the impression that 2014 vs 6061 vs 70xx was always a progression from flexy and less light to lighter and less flexy as the numbers went up. Couldn't say how/why though.
Originally Posted By: IndyIan
Originally Posted By: whizbyu
Trying to understand why one is more expensive than the other. Specifically looking at different brands of stems for a mountain bike. Nothing daring like downhill runs or hucking; just trail riding on technical singletrack.
If you don't really care about weight, just get one that looks semi-beefy. I went with a light duty DH one on my XC bike as that's one part I never want to fail...
I'm definitely a clydes and have run alloy stems with pretty significant flex and never had an issue. Never saw a stem failure working in the shop either. I'm sure they happen but maybe not the most frequent problem (lots of taco'd front wheels!). That said, a strong rigid stem offers more than just piece of mind. It offers better power transfer and handling as well- especially if you are well above 200lbs!
 
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One thing to be aware of is that 6061-T6 has a rather low fatigue life, meaning that it will crack after being repeatedly flexed back and forth. I don't have a good handle on whether or not this would be an issue for most bike riders but if you do a lot of off road riding on an aluminum frame mountain bike it could become an issue after, say, 5 or 10 years of riding. Just something to be aware of. I work in the aerospace industry and once was asked to reduce the weight (mass) of some helicopter components that were made of 6061-T6. We decided to recommend replacing them with different aluminum alloys (e.g., 7075) because of the low fatigue life of 6061-T6. I have a 6061-T6 aluminum road bike made by Trek that I bought used, so this is something I need to keep an eye on when I ride it. The load cycling on a road bike should be less than for a mountain bike but could still be significant if a rider with powerful legs is really honking on it. I'm not saying not to buy a bike made of 6061, but just be aware that the fatigue life is lower than for other aluminum alloys or steel.
 
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^^^I take it that the fatigue cycle life for most 2.5 titanium is greater than that of ANY aluminum, but less than most steel tubing used in road bike frames? shrug
 
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Originally Posted By: dailydriver
^^^I take it that the fatigue cycle life for most 2.5 titanium is greater than that of ANY aluminum, but less than most steel tubing used in road bike frames? shrug
I have a couple of cracked Ti frames in my garage. I'm not at all sure fatigue life of Ti can be readily compared to a cast iron bicycle, or aluminum one.... smile I think a couple of big hits or a few crashes, plus rider weight and terrain play too much of a role to "know" objectively which material is better. Like many others, I'm in the aviation industry. Our Eurocopter EC135 has a number of 2024 T3 components. They ALL have massive intergrannular corrosion issues that result in rapid failure. That's unusual because 2024 T3 is not generally subject to intergrannular corrosion unless improperly heat treated.... My point is this. I'm not at all sure that you will be able to completely predict your frame's performance based on alloy specification. It's more likely in my mind that the source of the aluminum, the manufacturing techniques, plus the proper application of the aluminum in question, are more important. If you can, choose a manufacturer that will stand behind their products after many years.
 
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Originally Posted By: buck91
I'll admit that my understanding of various alum alloys is sadly lacking but I always was under the impression that 2014 vs 6061 vs 70xx was always a progression from flexy and less light to lighter and less flexy as the numbers went up. Couldn't say how/why though.
Originally Posted By: IndyIan
Originally Posted By: whizbyu
Trying to understand why one is more expensive than the other. Specifically looking at different brands of stems for a mountain bike. Nothing daring like downhill runs or hucking; just trail riding on technical singletrack.
If you don't really care about weight, just get one that looks semi-beefy. I went with a light duty DH one on my XC bike as that's one part I never want to fail...
I'm definitely a clydes and have run alloy stems with pretty significant flex and never had an issue. Never saw a stem failure working in the shop either. I'm sure they happen but maybe not the most frequent problem (lots of taco'd front wheels!). That said, a strong rigid stem offers more than just piece of mind. It offers better power transfer and handling as well- especially if you are well above 200lbs!
My buddies flexy mtb stem did break, but fortunately on a wheelie pull up, so no steer tube through ribs... I won't get an Al steer tube either if I can help it, the same buddy almost went quadriplegic from one of those breaking... I snapped one bar off on a small drop and I don't really want to repeat that, let alone a have big crash. I've broke a crank too, and now just run beefy ones. For the few ounces difference, and like you say, the more solid and direct feel, I'd rather go with the practically unbreakable(for me) parts and lose the 1/2 bike length on a long climb.
 
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