A surgical instrument is disclosed. The instrument comprises a rotary motion generator, a trigger configured to actuate the rotary motion generator, and a shifting assembly. The shifting assembly comprises a first gear selectively drivable by the rotary motion generator, a second gear selectively drivable by the rotary motion generator, and a toggle configured to switch between the selective drivability of the first gear and the selective drivability of the second gear. The shifting assembly further comprises a biasing mechanism engaged with the toggle, wherein the biasing mechanism is configured to motivate and maintain an operative meshment between the rotary motion generator and one of the first gear and the second gear. The surgical instrument further comprises a rotatable shaft, an end effector comprising a first iaw and a second iaw, and a firing member moveable relative to the end effector during a firing motion.