(why does bike industry say "alloy", doesnt that just mean aluminum of some sort?),
An alloy is basically a mixture of two or more metals. In the bike industry, "alloy" tends to be used to describe parts made from an alloy that consists mainly of aluminium (i.e. "aluminium alloys"), despite the fact that a lot of steel bike parts are made from alloy steels, and quite a lot of titanium parts are made from titanium alloys.