The chainrings are part of your chainset, and over time they wear out through use (contact with the chain). Signs of this wear are very sharp (or hooked) teeth, or slipping when you put the power through your pedals. A change of chainrings can bring back that new feeling to your bicycle, ensuring that all the power you put in results in you going as fast as possible. Road bike chainrings come in a variety of sizes with different numbers of teeth and are also suitable for cyclocross, touring and triathlon bikes. Track bikes have a single chain ring.