Abstract: A system for synthesising inertia in exercise equipment, the exercise equipment comprising a rotatable member to which a user applies a user torque in use, the system comprising: an electric drive system comprising an electric motor operably connected to the rotatable member, the electric motor configured to impart a resistance torque, in use, on the rotatable member of the exercise equipment, whereby the resistance torque opposes the user torque; at least one sensor for monitoring a user input to the rotatable member; and a control system, comprising at least a processor and a memory, wherein the control system is connected to the at least one sensor and is configured to use the input from the at least one sensor and at least one predetermined parameter storable in the memory, to determine a resistance torque and to provide instructions to the electric drive mechanism to impart said resistance torque on said rotatable member.