Patent ID: 7857732

Claim:
A sway-capable stationary bicycle comprising: a substantially planar upper support structure having a length, a width and four corners defining a rectangle, presenting a front edge and a back edge each of the width of the structure; a bicycle frame symmetrical about a substantially vertical frame plane, the frame including a lower substantially horizontal frame member rigidly joined to the upper support structure with the lower horizontal frame member in the plane of the upper support structure and bisecting the plane of the upper support structure along its length; a substantially planar lower support structure of the same length and width of the upper support structure, also presenting a front edge and a back edge, the lower support structure positioned with each corner directly below each corresponding corner of the upper support structure; four resilient members of a common relaxed height, one member at each corner joined to the upper and lower support structure, spacing the upper and lower support structures apart by an equilibrium height determined by the combined weight of the upper structures and a rider if mounted; a first vertically-oriented stabilizing member constrained to translate only vertically, presenting a hinge at an upper end with a horizontal hinge axis, the hinge rigidly joined to the underside of the front edge of the upper support structure at substantially the center of the width, in a manner to direct the hinge axis in the length direction of the support structure, below the support structure; and a second vertically-oriented stabilizing member constrained to translate only vertically, presenting a hinge at an upper end with a horizontal hinge axis, the hinge rigidly joined to the underside of the rear edge of the upper support structure at substantially the center of the width, in a manner to direct the hinge axis in the length direction of the support structure; wherein the hinge axes form a lengthwise axis about which the frame plane of the bicycle frame may rotate within the constraints of the comer resilient members, and the two stabilizing members keep the upper and the lower support structures substantially aligned vertically.