Manufacturers descriptionThe newest addition to the XTR Dyna-Sys drivetrain is the RD-M985 Shadow Plus rear derailleur. The Shadow Plus feature provides a selectable pivot for the pulley cage that can use a heavier spring and increased pivot friction to counteract the forces of up and down chain momentum in rough terrain. The chain bouncing can often cause noise as the chain slaps the top and bottom of the chainstay, or even cause the chain to derail from the front ring in extreme circumstances. The new pivot when selected to the "ON" position dampens the cage and consequent chain movement for a nearly silent and stable riding experience. In the "OFF" position the derailleur will function like a standard Shadow rear derailleur and eases the installation and removal of the rear wheel by relaxing the spring tension on the cage.
