The saddle height of a cycle road racer influences the competitive performance of the cyclist. Cyclists can adjust the saddle height carefully according to their kinesthetic sense while riding a bicycle. The saddle height control system we have developed consists of a saddle height control device and a measurement instrument for a surface electromyogram (SEMG). The evaluation criteria for the saddle height based on SEMG signals, which are measured from the leg muscles during pedaling exercise, are established. Our experiments indicate that the saddle height was controlled at a relatively low level regardless of the cycling level of the subjects. The effects of muscle fatigue due to pedaling exercise are suspected to affect these experimental results.