A derailleur system is provided that moves the derailleur cage in a substantially rectilinear path. The derailleur is mounted to a frame having a gear cassette mounted thereon. The gear cassette includes an axis of rotation. The derailleur includes a drive member engaging the gear cassette. The derailleur is positioned on the frame adjacent the gear cassette, and including a spatial linkage having a stationary link, a floating link, and a cage assembly having two pulleys each defining an axis of rotation. The drive member engages each of the pulleys. The path of the floating link is substantially linear through substantially its entire range of motion and variously aligns at least one of the pulleys with the gear cassette.