Shifting between gears in all weathers, front and rear derailleurs – known as ‘mechs’ – do a sterling job, but are in the firing line of anything your wheels throw up from the road or trail. Mountain bike derailleurs are made to work in all conditions, including mud, rain and grit, and need to be robust enough to take a knock or two from trees and rocks. Road bike mechs don’t have to face up to quite the same conditions, but are nevertheless designed to work smoothly under pressure, while being light and functional. In addition, we have spares such as jockey wheels – the little cogs which fit inside the rear mech – and clamps for the front mech. Top brands include Shimano and SRAM.