Abstract: Apparatus measures output parameters including torque, work, power, rpm and time for selected rotations of the user of a power-using device having a pedal-crank assembly. Torque vs. angular position values are input from rotating strain gauges and angular position sensors to a programmed microprocessor which stores and processes this data. An approximate-integration algorithm produces a value for work produced over a selected rotation. This work value is further divided by the time interval to produce a value for the instantaneous power being produced. With appropriate sensors, many forms of data for both right and left crank arms can be displayed and/or stored separately.