While writing about rims, we realized that the metal, its alloy composition, and the alloy's characteristics were of importance, yet there has been no objective discussion of them in a single compiled source. As you've seen, whenever possible we reveal the metal material used, its heat treatment and the manufacturing techniques used, but a knowledge of the metal has been implied. Here is where we will teach you explicitly about some of the metals used in making after market bicycle replacement parts, which will give you an understanding of why some replacement parts are of better quality than the original parts that come on bikes originally. This section is complicated, but if you get it, you'll really be able to impress your friends!!