Joint torque is estimated for a joint of a cyclist using a simple configuration.A joint torque computation system (10) includes a joint torque computation device (12), a detection section (14), an input section (16), and an output section (18). The joint torque computation device (12) includes a data acquisition section (122), a torque estimation section (124), and a change estimation section (126). The joint torque computation device (12) employs load data representing load applied to a pedal, skeletal data, and structural data to compute a change of joint torque when a position of a saddle has been displaced, and to output the saddle position to the output section (18). The change estimation section (126) uses plural estimated joint torque changes to decide a saddle position enabling the cyclist to develop their maximum power.
