Abstract: An exercise machine is for performing a striding exercise motion. The exercise machine has a frame; first and second pedal members; first and second foot pads on the first and second pedal members, respectively, each of the first and second foot pads being movable along an elliptical path during said striding exercise motion; and first and second rocker arms each having a first end that is pivotable with respect to the frame about a rocker arm pivot axis and further having a second end that is pivotable with respect to one of the first and second pedal members about a pedal lever hub axis. The frame has first and second frame portions. The first frame portion supports the first and second rocker arms and is pivotable about a frame pivot axis relative to the second frame portion. Pivoting the first frame portion relative to the second frame portion adjusts a position of the rocker arm pivot axis, which thereby changes a shape of the elliptical path.

Abstract: An exercise machine has a first frame member, a second frame member that is movable with respect to the first frame member, and a locking device having at least one cam that is rotatable into and between a locked position in which the cam abuttingly engages and thereby retains the second frame member in position with respect to the first frame member and an unlocked position in which the cam is spaced from and thereby frees the second frame member for movement with respect to the first frame member. The cam has an engagement surface with a contour that follows a logarithmic spiral curve defined by the following parametric equations: x(t)=r(t)cos(t)=aebt cos(t), and y(t)=r(t)sin(t)=aebt sin(t), wherein e is the base of natural logarithms and a and b are arbitrary positive real constants.