A surgical instrument is disclosed. The surgical instrument can include an end effector, comprising an anvil and a staple cartridge. The surgical instrument can further include a shaft defining a longitudinal axis. The surgical instrument can also include an articulation joint, wherein the end effector is rotatably connected to the shaft about the articulation joint between an unarticulated position and at least one articulated position. The surgical instrument can include means for adjusting the length of a firing stroke as a function of the degree in which the end effector is articulated relative to the longitudinal axis. The surgical instrument can include a sensor configured to defect shifting of lateral portions of a flexible firing bar that extends through the articulation joint. Additionally or alternatively, the surgical instrument can include a relief feature configured to accommodate shifting of lateral portions of a flexible firing bar.