Not to sideline the thread. But can someone tell me the difference between Scandium and 7000 or 6000 series Aluminium.
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Easton Aluminium and another interesting topic on Aluminium
7005 vs 6061aluminum topic. Also Scandium is only available in 7005 aluminium and Easton Ultralite available as 6069 aluminium. The 6069 T6 alumnium will need a heat treating treatment to regain its mechanical characteristics.
Of course there are both low end and very high end frames are made in 7005 tubing. 6061 tends to be used on mid to high level frames because of production costs.
6XXX series tubes are alloyed with Magnesium and Silicon and makes a moderate strength alloy that tends to be more ductile. The material itself is usually pretty cheap which is why most heavy low end aluminum handlebars, stems, and seatposts are made from it. But because its also ductile, it makes for a good rim material. However, when welded...it loses a lot of its strength. In order to regain the strength it must be heat treated which is a time consuming and expensive process. This is why you don't see low end aluminum frames made with it...the production costs far outweigh the material savings when used in a frame. Because it is so ductile, tube manipulation is easier so many manufacturers use it because they can make many different tube shapes fairly easily with it.
7XXX series tubes use Zinc as its main alloying agent. It is harder and stronger but also less ductile (tends to snap vs bend). Because of its strength, it is the primary material used in high end alloy bars and seatposts (think Thompson here) as well as high wear items like chainrings. The material costs more than 6061 but because most 7005 frames do not require heat treatment, they can be produced cheaper...which is why department store bikes use it. But very high end tubing such as Easton Ultralight and SC7000 (with added scandium) are 7005 based tubing sets as well.
Giant Alcoa 6013,Cannondale CAAD 3,4,5,6,7,8,9,10 and Trek Alpha Alumnium SLR use custom 6XXX series alloy but receive a heat treated treatment to regain mechanical characteristics.
Here is a review from
7005 vs 6061aluminum. Easton frames especially Scandium and Elite ones were prone to cracking and a heavy rider isn't recommended.