A wheel suspension system having under powered acceleration a squat response that begins in the realm of anti squat and passes through a point of lessened anti squat at a further point in the travel.
This application is a continuation in part of U.S. application Ser. No. 10/669,412, filed Sep. 25, 2003 now U.S. Pat. No. 7,048,292, which is incorporated herein by reference in its entirety.
A rear suspension for a vehicle such as a bicycle or motorcycle that includes a frame, a swinging arm integral with the frame carrying the axle of a drive wheel hub and a shock absorber whose ends are secured to the frame and to the swinging arm, the swinging arm being secured to said frame by at least two articulation means so that the swinging arm pivots about an "instantaneous centre of rotation" that is movable when the hub is displaced on either side of its reference position corresponding to the position of the hub axle when the vehicle is in a static equilibrium position, characterized in that the instantaneous centre of rotation is displaced upwards along a parabolic path, the asymptote of which is oriented towards the rear free end of the swinging arm carrying the axle of the hub when said hub is displaced above its reference position.
A bicycle rear suspension system has a virtual pivot point that is close to a junction between a chain and a front driving sprocket when a piston rod travels relative to a cylinder body by 1/4 to 1/3 of a maximum displacement value, and that moves rearwardly when a rear wheel moves upwardly away from the ground. A line interconnecting an instant center of a rear triangular frame and a contacting point between a rear wheel and the ground forms an angle of about 45.degree. with respect to a horizontal line.
The present invention is a bicycle including a bicycle frame and a rear wheel suspension system that is attached to the frame. The rear wheel suspension system includes a rear wheel swingarm and a shock absorber that is engaged to the swingarm to control the motion of a rear wheel of the bicycle. A change in the vertical wheel travel (.DELTA.VWT) of the rear wheel is related to a change in the length of the shock absorber (.DELTA.SL), providing a shock rate (SR) according to the relationship: SR=.DELTA.SL/.DELTA.VWT. The shock rate (SR) changes throughout the vertical wheel travel of the rear wheel, such that the change in the shock rate dSR/dVWT has a change in sign as the rear wheel travels through its vertical wheel travel. The shock rate may at first decrease in value and subsequently increase, or initially increase in value and subsequently decrease throughout the vertical wheel travel of the rear wheel. In various exemplary embodiments the swingarm may be attached to the frame at a single pivot point or through a linkage system.
