A computer-based instrumentation system which accurately measures the seat, handle-bar, and pedal loads together with the absolute pedal position during bicycling is presented. The instrumentation system is unique in that for the first time it allows measurement of handlebar and seat loads. With three test subjects riding on rollers, which simulate actual bicycling, loading data were recorded at constant power for different pedaling rates. Analysis of the data enables load characteristics of all three sources (i.e., pedal, seat, and handlebar) to be categorized as being either subject and pedaling rate independent or subject independent but pedaling rate dependent. A complete set of loading data for one subject is presented to illustrate these characteristics. One interesting finding is that peak levels of all but one of the pedal loads are inversely related to pedaling rate. Peak levels of seat and handlebar loads reactive to the driving loads on the pedals, however, are directly related to pedaling rate. Another interesting result is that handlebar and seat loads, except for the lateral seat moment, go through two cycles for each revolution of the crank arm. The interpretation of these results, as well as others, provides insight into the biomechanics of the pedaling process.