The components of our rig, which is used for the dynamic calibration of cycle ergometers, were purchased for $4,080 (USA); interfacing the instrument with a computer and printer increased the cost by an additional $2,550 (USA). The rig is essentially a torque balance and was therefore validated against the primary measurements of: angular velocity (rev.min-1), distance (m) and mass (kg). Summing the inaccuracies associated with these 3 measurements yields a worst case error of only 0.3%. The coefficients of variation for a dynamic calibration rig and mechanically braked Monark cycle ergometer assembly ranged from 0.6 to 3.2% for 6 trials at each of the following power outputs: 117.7, 176.6, 235.4, 294.3 and 353.2 W. The instrument therefore has a high degree of precision.