The bicycle chainring is an essential part of the bike. It is designed to be placed on the crankset. It must be chosen with the utmost care. On the bike, there can be 1, 2, or 3 chainrings. The chainring is a cog wheel on which the links of the bicycle chain are placed. The diameter of the chainring's fixings is essential information to know if a chainring is compatible with its crankset. This measurement is called BCD (Bolt Circle Diameter). Chainrings for vintage bikes are made of steel or aluminum.