NOVELTY - The device has a crank (2) rotatably mounted to a support structure e.g. frame (9), for rotation about an axis. The crank has a pair of pedals (3) that are movable along a circular path. A control system controls a force-generating device e.g. alternator (11) and mechanical brake, connected to the crank to cause a resistance force experienced by a user pedaling the device to be greater in the forward portion of the circular path than in the rear portion of the path. The difference between the expected and measured variable is used as a control input to control resistance forces.    USE - Excercise device e.g. stationary bike, treadmill, stair climber, rowing machine, weight lifting machine, swimming machine, and tennis/baseball practice machine, for simulating a physical activity (claimed) e.g. exercise.    ADVANTAGE - The control system controls the force-generating device e.g. alternator, connected to the crank to cause the resistance force experienced by the user pedaling the exercise device to be greater in the forward portion of the circular path than in the rear portion of the path, where the difference between the expected and measured variables is used as the control input to control resistance forces, thus accurately simulating the dynamics of the exercise being simulated, and making the user to experience force similar to the forces that are encountered if the user actually performs the physical activity rather than using the exercise equipment, and hence enabling the user to exercise more effectively or longer with the same perceived effort. The control system eliminates a need for flywheels that are required for the affects of momentum during the actual physical activity being simulated.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a stationary bike.    Crank (2)    Pedals (3)    Drive member (4)    Pulley (4B)    Flexible drive member (5)    Frame (9)    Alternator (11)    Electronic control (25)    Battery (26)    Handle bars (27)    Display screen (50)