This study aims to develop an assistance system that automatically adjusts the mechanical components of a bicycle against the physical properties of a cyclist. Previously we investigated the effects of changing both saddle height and fore-and-back position for the muscle activity pattern of leg muscles. As the result of this investigation PCA scores for the activities of leg muscles, where the saddle was set to a favorite height of a skilled cyclist, came to near zero. In order to understand the meaning of this results, we investigated the effect of fore-and-back position for the muscle activity of leg muscles. The experimental results estimated an appreciate saddle setting for a cyclist.