Bicycles are popular with the general public because of their low price and easy maintenance, and they will be an important vehicle in the future because of their low environmental load. Improving the comfort of the ride is one of the important factors that will lead to increased popularity. We attempted to increase comfort by reducing vibration, and evaluated the results with a subjective test. We determined that low frequency vibration of the seat greatly affected the comfort of the ride. We then performed a transfer path analysis (TPA) and a hammering test to investigate how the vibration characteristics of the bicycle affected the vibration of the seat. Through TPA, the rear of the bicycle frame was found to have a high influence on the seat vibration, and the vibration behavior was obtained by modal analysis. In order to reduce seat vibration, a spring was inserted in the front of the seat and, to increase the stiffness, a steel plate and bolts were attached to the rear of the frame. As a result, the seat vibration while riding was decreased by about 10 dB, and the comfort of the ride was greatly improved.