A seat support platform is pivotally supported on a base member. A rotatable locking element is provided on the platform to selectively lock frame members of a saddle thereonto. The base is adapted to be mounted to a support frame/chassis such as that of a stationary bicycle or the like. A resilient biasing arrangement enables the saddle to move from side to side relative to the base member to enable a user to sway from side to side in a more natural manner when riding on the saddle.