Aluminium Grades?

[burridge1984]

Bit unsure what these actually mean when considering a bike.

Having been looking at hardtail mountain bikes and see a mix of frames.
Some are listed as 7005 grade aluminium, and some 6061 grade (the main grades I have seen).

Could anyone help with what this actually means? Is it strength or cost related? Are there grades to avoid etc?

Thanks in advance.

[itsnotarace]

It is to do with the amounts and types of other metals that are present, first result in google

http://www.bikeforums.net/showthread.php/15193-606...

[shalmaneser]

If you really want to get into the metallurgy there are variations between grades but certainly nothing to worry about.

Some extremely high grade aluminium alloys such as the scandium alloys for example have specific qualities but for the vast majority the aluminium grade will have nothing to do with the bike purchase decision.

[paranoid airbag]

^what he said. <geek>Chemically, 7005 using zinc and magnesium as alloying elements and slightly higher strength, but more expensive, than 6061, which uses magnesium and silicon </geek>. But unless you have a special use for your frame (e.g. weight weenies and time triallists need carbon, tourers need steel), any of the common materials used will do.