The rear gear, AKA derailleur or mech, is the mechanism that moves the chain from one rear cog to another. We stock a wide range of rear mechs suitable for near-any bike - road, mountain or hybrid - with a Shimano or SRAM drivetrain, whether it has 5, 6, 7, 8, 9, 10, 11 or 12 rear cogs. Discover our range and find which mech set is right from you. Our mountain bike rear derailleurs have a slightly larger capacity than those made for road bikes to maintain accurate shifting while not getting too clogged up with mud and trail debris. While our road mech sets are lighter and will sharpen up your shifting seamlessly through the gears.