Shimano Saint Shadow + Rear Derailleur
Shimano's Saint Rear Derailleur is packed with World Cup-worthy features, like an integrated skid plate, a urethane bump stop, and low-profile Shadow positioning, all of which protect your derailleur as you smash through rock gardens and overgrown singletrack. Shimano Plus Technology minimizes chain and impact noise, and maintains perfect chain tension so you can shift with precision and authority no matter how rough the terrain gets. The Saint Rear Derailleur also has a mode converter that lets you use either a close-ratio DH cassette, or a wider-ratio freeride cassette.
An important part of a rear derailleur's job is keeping the chain taut as you change gears. Chain-wrap capacity is a number that tells whether or not a derailleur will be able to do this on the drivetrain you plan to use it on. Calculate chain-wrap capacity with this formula: Chain-wrap capacity = (large chainring - small chainring) + (large rear cog - small rear cog). Example: 44/29 chainrings and a 11-28 cassette: (44 - 29 = 15) + (28 - 11 = 17) = 32-tooth chain-wrap capacity.