This document describes the design of an instrumented wheelchair wheel called a propulsiometer that measures forces during wheelchair propulsion. The propulsiometer consists of a data acquisition system, load cell, wireless transmitter, battery, and other components. It has 6 analog channels, 4 digital channels, and can sample at over 200 Hz while consuming around 5 watts of power. The design meets about 85% of requirements and successfully transfers data from the load cell and encoder to a computer. The goal is to further develop this affordable device to help assess wheelchair propulsion and reduce overuse injuries.