Bicycle Mechanics - 6061-T6 vs 7005 aluminum?

can somebody compare the two metals for mtb frame use?

6000-series is aluminum alloyed mainly with magnesium, and tends to be a bit more ductile (for instance, it would be more apt to wilt or buckle than to snap, compared to 7000-series).

7000-series aluminum is alloyed primarily with zinc. It tends to be harder and stronger but perhaps more brittle. Excellent material for chainrings due to its hardness, too.

The T6 refers to the degree of heat treatment. I'm not a metallurgical expert, so that's about all I have to contribute.

There are good frames made with both materials. My '98 Gary Fisher Paragon is a 6000-series frame, as is my Cannondale touring bike.

I'm interested in these grades.

Are the types of aluminum created by the manufacturers or by other institutions that the bike companies simply use under licence? I know for example, that Klein, were famed for the way they used aluminum, but were the processes their own or someone elses?

It has always been my understanding that the frame builders work with tubing mfrs, the metal experts, to develop the alloys and perhaps the tubing shapes/cross section. Then the tubing mfrs, Reynolds, Columbia, etc. actually make the tubes for the frame makers. The making of the tubes to the appropriate shapes at the appropriate spots for the stresses involved is a science and near art unto itself. The whole tubing design/manufacture is a collaborative effort.

Easton are a high-end maker of Al tubing for bikes. As well as a variety of stock shapes they draw custom tubes at thr request of builders. I think it was Serotta who started the trend for custom tubesets. Before that everyone used whatever Reynolds/Columbus/Tange produced.

http://www.eastonbike.com/tubesets_top.html

This is fairly typical of modern tube manufacturers in all materials.

Primary aluminum is produced as ingots [large blocks] or rolls[light gauge] of sepcific alloys. Pure, unalloyed aluminum is a very uncommon commercial commodity. The companies that produce primary alumium are rather few -- Alcan, Alcoa and Kaiser leap to mind immediately -- principally because of the cost and economies of scale involved in producing aluminum from bauxite.

The primary manufacturers sell ingot and rolls to secondary manufacturers like Easton, Columbus, Tange, Dedaciai, etc. These guys extrude or draw the metal into specific tube shapes and sell them to bike manufacturers. In a sense, a fair amount of the Italian, American and Japanese aluminum is, in fact, Canadian in origin and Jamaican or Australian [the sources of Bauxite] before that.

The shape of the tubes is actually more important to the ride quality and durability of a bike than the actual alloy employed in their manufacture. It's conceivable that a manufacturer could make a 6061 tubeset that rides like a 7005 tubeset by manipulating tube shapes.

The key difference -- in terms of bikes -- between 6061 and 7005, however, is that it is easier to weld 6000-series aluminum, so it was the first aluminum widely used in bikes and the alloy most likely to turn up at the lower end.

Velo....very good, except that 6061 requires a very high temperature,expensive heattreatemnt after welding,almost to the melting point. 7005 requries very little the way of heattreatment , is less expensive and is more often found on less expensive bikes. Cdale is one of the few using 6061.....anyone who thinks they can tell the difference between ALLOYS in the finished product is kidding themselvdes. And< I think, contrary to what Mech said, 6061 uses the zinc and is the harder or less flexible. Not that it really matters.

From manufacturer's:
http://www.columbustubi.com/english/alluminio/index.htm
http://www.reynolds-cycle.com/internet/english/prodrange/aluminium/aluminium.htm
http://www.bringheli.com/dedacciaialum.html
http://www.eastonbike.com/tubesets_top.html

thanks for the replies:beer:

i've learned a lot, but which one is zinc and which one is mag?

and which one is found on higher end frames and which on lower?

can someone make sure?

The 6000 series alloys are primarily made with Magnesium and Silicon. T6 means the material has been solution heat treated then artificialy aged without cold working(ie rolling or folding and pressing).

The 7000 series is alloyed with zinc and doesn't require the extensive heat treatment of the 6000 series.

The 7000 series came later than the 6000 series. It is now the most extensively used alloy due to its greater ease of manufacture.

Both materials can be found at the lower end and the upper end.
It depends more on the frame manufacturer as to the quality of design. Factors such as double butting, weld quality and tube shape come into play here and are being continually developed.
The best guide to quallity I should think is to look at who manufactures the tubing ie, columbus , reynolds etc. alongside the frame manufacturer ie Cannondale, Treck, Look, etc.

I hope this helps.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1863186452

since people here are so knowledgeable, can someone tell me if this is a good quality frame? thanks

Everything on the 6061 tubing and the 7005 tubing is very accurate, but after welding 7005 tubing it needs to "cure" about 30 days to get to full hardness. So you often find 7005 frames built overseas, since it has to be shipped and it eliminates the extra T6 step from the manufacturing process. The domestic frames are in the bike shops much sooner.

I was also confused when trying to figure out which AL was better or found on high end bikes. Seems like 6061 and 7005 are both found on low and high end... so I guess its all a wash.

For a description of the terminology and a decoder ring:

http://www.bikepro.com/products/metals/alum.html

Its interesting to note that 9000 series has not been defined by the industry, so Trek's ZR9000 (zirconium) is simply the name of their home-grown AL mixture.

Also, there are probably different grades of 6061, etc. Some manufacturers may have better quality control or tolerances on the impurities, so I would guess that all 6061 is not equal.

You can also check out reynolds for comparisons and how tubing is made.

http://www.reynolds-cycle.com/internet/us/tech/ustech.htm

Tfunk I think you can get an similar frame at Jenoson or supergo, for about $115 to 130?
Ive seen Leader bikes and they arent that pretty... more your Wally world type units, so maybe they are just looking to make a buck on em...?