Chainrings

The round, spiky bit attached to your cranks that pulls the chain round is a chainring. For example, a classic road racing bike may use a 53 t large chainring, whereas as part of a hill-friendly compact chain package, a bike more targeted at recreational and sporty cycling may use a 50 t large chainring.

The larger chainring provides you with larger, harder to turn gears that drive you faster per pedal revolution, so it is ideal for higher speeds, while the smaller chainring provides you with gears that are easier to turn but carry you a shorter distance per pedal revolution, so it is suitable for lower speeds, like cycling.