An articulating platform (20) that is used to vary the longitudinal and lateral angular displacement of an exercise bicycle (22) mounted thereon. The platform includes a bicycle mounting base (24) configured to accept the footprint of a conventionally dimensioned exercise bicycle. The base (24) pivots in both a longitudinal axis and a lateral axis, thereby simulating uphill and downhill bicycle riding and turning when leaning sideways in a turning direction. The base (24) is preferably articulated by a D.C. motor drive system or optionally by a gear motor, pneumatic, hydraulic and worm drive systems each having controls for initiating directional articulation. A platform enclosure (40) supports the base and the drive system to provide a safety barrier for protecting moving components of the platform.