A wheel assembly including a sensor for measuring wheel movement is provided comprising: a frame member; an axle fixed to the frame member; a wheel rotatably mounted to the axle and comprising a wheel recess; a code ring located within the wheel recess for rotation with the wheel; and a sensor device coupled to the frame member and located adjacent to the code ring. The sensor device senses movement of the code ring and generates an output signal indicative of the wheel movement. A materials handling vehicle comprising the wheel assembly is also provided.