velo

I'm looking at two different bike frames. One says it is 6000 series aluminum, and the other says 7005. What does this mean? Is one better than the other? How?

khuon

7000 series aluminum is a cheaper aluminum that doesn't get heat-treated after welding. They're generally found on lower end Al bikes. The alloying of elements involved give it an almost tin-can feel. 6000 series Al is higher grade stuff but does need to be heat-treated. Many companies take the basic 6000-series and modify it somewhat. A 6000-series Al bike will have a much smoother ride than a 7000-series bike.

Hunter

https://www.eastonbike.com/downloadab...l%20Alloys.pdf
https://www2.sjsu.edu/orgs/asmtms/artcle/articl.htm
These are probably the most informative info there is.

ncernitz

There are many grades of aluminum alloys and many ways to post process it. America's largest jet manufacturer uses 7000 series to make its major air frame components and uses 6000 series for its cockpit and cabin components. Many 7000 alloys will air harden, or age, and not require heat treating. At any rate, I believe that with out a metalurgical break down, determining with series is better is futile..........

Retro Grouch 

7000 series aluminum actually costs more, but doesn't require the extensive heat treating after welding so it generally costs less overall to produce a bike frame.

6000 series aluminum has to be heat treated, almost to the melting point after welding. If you already have the heat treating ovens, buying the less expensive raw material makes more economic sense.

I have personally never owned a bike frame that didn't last longer than I wanted it to, so I don't have an opinion about which might make the better bike frame.

dexmax

If my memory serves me well, in materials engineering, the first digit indicates the principal alloying element, which has been added to the aluminum alloy and is often used to describe the aluminum alloy series, i.e., 1000 series, 2000 series, 3000 series, up to 8000 series
The second single digit, if different from 0, indicates a modification of the specific alloy, and the third and fourth digits are arbitrary numbers given to identify a specific alloy in the series.

1= 99% Al (almost pure Al)
2= Copper
3= manganese
4= Silicon
5= Magnesium
6= Magnesium & Silicon
7= Zinc
8= others

Sometimes manufacturers also give out temper designations... ie t6, 6000-t4, etc.
The different series of aluminum alloys have considerable differences in their characteristics and consequent application. There are two general types, the heat treated and non-heat treatable type.
The 1xxx, 3xxx, and 5xxx series wrought aluminum alloys are non-heat treatable and are strain hardenable only. The 2xxx, 6xxx, and 7xxx series wrought aluminum alloys are heat treatable and the 4xxx series consist of both heat treatable and non-heat treatable alloys.The heat treatable alloys acquire their optimum mechanical properties through a process of thermal treatment, the most common thermal treatments being Solution Heat Treatment and Artificial Aging. Aging is the precipitation of a portion of the elements or compounds from a supersaturated solution in order to yield desirable properties.
The non-heat treatable alloys acquire their optimum mechanical properties through Strain Hardening. Strain hardening is the method of increasing strength through the application of cold working.T6, 6063-T4, 5052-H32, 5083-H112.

legalize_it

thats crap, no one can tell the different Al series by riding. i believe it is possible to tell the difference between steel and Al by riding though...

Yashrg

Landed on this page through a google search. And I was wondering if there is a weight difference between 6000 and 7000 series aluminum.

Also, trek calls the 7000 series aluminum their premium alloy while the 6000 are their lower lines.

DannoXYZ 

The 7005 has slightly more ultimate tensile-strength and a lot more fatigue-resistance. It is possible then, to build a 7005 with less material for the same strength. But typically the difference is less than half a pound. It's hard to compare because no manufacturer makes the exact same model in each alloy.

bradtx

At one time 6061-T6 was considered by consumers the aluminum for premium aluminum frames and 700X relegated to the lower end as it was percieved as more brittle. In the late 90s that seemed to change as different series of aluminum frames began to appear, my '98 Trek mountain bike's ZX aluminum is 6005 series (IIRC), for example and different (improved?) welding techniques for 700X series came online.

Here's a good write up on the subject: https://www.bikeforums.net/archive/index.php/t-6981.html

Brad

DannoXYZ 

Also this site gives you a lot of good specs: https://matweb.com

BCRider

Other factors in terms of frame geometry and tube set sizes and buttings will produce effects that you'll feel far more than the choice of aluminium.

The market is normally very suspicious of anything new when it is first introduced so 7005 was used on mid line bikes where folks would be more tolerant of something new due to the price point. Because of that some folks still feel that 7005 denotes a lesser quality bike. But really either alloy is fine and any differences that are PURELY due to the alloy would be invisible to the rider. And at this point both alloys have certainly proven themselves as being durable over the long term.

fietsbob

Who builds it and what purpose it was made to serve matters more than what the recipe is of the alloy they use, if they are good at engineering the product, they will use the right materials,

unless 'as cheap as possible' is what the customer wants,
then cutting corners is what is asked for.. YGWYPF

there are post welding treatments whole products can be submitted to ,
normalizing to reduce weld created stresses and heat treatments also

7005 ..0.45% Mn,1.4%Mg, 0.13%Cr, 4.5%Zn, 0.04% Ti, balance is Al.

My Koga Miyata WTR frame is made of custom drawn shaped
[top and downtubes are not round, + there are gussets welded on ]
7005 which is said to be triple hardened ,
after it has been welded and hand finished ,
so welds are smooth and the completed bike is one in the top of the range ,
many people have ridden them, loaded up, self contained with touring gear,
around the world.

as to the how much does it weigh thing , a cubic foot of solid aluminum will weigh
darn near the same no matter what its alloy.
just like Steel, by the solid block..

Same schtick .. a stronger alloy, higher tensile strength,
will let you use less to do the desired task,

so a cheap frame will be generous thick tube wall of the lower strength steel,
or aluminum, .. to keep the product working.

and the personal injury lawsuit costs at a reasonable level.

kh777

Here's another link (Columbus Tubing - aluminum): https://www.columbustubi.com/eng/3_2.htm

With the exception of the Columbus Starship tubing (6000 based), most of their other aluminum offerings are/were 7005 and were used on aluminum Colnagos, Pinarellos, etc. Not exactly low end stuff (unless compared to steel or carbon), although I'm sure there are low-end 7000-series aluminum bikes out there...

|3iker

Wow.... 6yr thread resurrection.

himespau 

Don't you love it when zombies are brought back from the dead just in time for halloween?

JPMacG

I find this a very interesting thread. So what if it is old - it is more interesting than most of the recent threads.