Different alloys offer slightly different characteristics. Some alloys are stiffer than others. Some are lighter or more resilient than others. The alloy plays a major role in the ride quality, weight, and durability of the rim.
The two most common aluminum alloys used for building bike rims include 6061 and 7005. Of the two, 6061 is a bit more common because it weighs less. A higher-end alloy, called niobium, is also used.
Aluminum rims start as a block of metal. This material is melted and pressed through a pre-made die that is shaped like a cross-section of the rim. The die shape determines the rim shape and wall thickness. This plays a big role in the weight and performance of the finished wheels.
