Bolt on a new chainset - the chainrings, and the crank arms which turn them - to improve your drivetrain performance. Chainsets and cranks are increasingly specialised and, depending on which one you choose, can save weight, improve power transfer through increased stiffness, or just be plain stronger. For mountain bikes, there are the ever-popular Shimano models, alongside Raceface and FSA, so you can choose the right model for your type of riding. For roadies, there's have double chainsets - compact versions for sportive riders, and standard for racers - and triple chainsets for those wanting a wider variety of gears. There are special chainsets for single-speed bikes as well.