Chainrings are the circular gears attached to the crankset of a bicycle. They work in conjunction with the chain to transfer power from the rider's legs to the rear wheel. Chainrings come in various sizes, affecting the bike's gearing and how easy or hard it is to pedal. Typically, a bike may have one, two, or three chainrings, known as single, double, or triple setups. The number of teeth on each chainring determines the gear ratio, influencing speed and climbing ability. Riders can choose different chainring sizes based on their riding style and terrain preferences.