Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
1999-04-06
2001-07-31
Olszewski, Robert P. (Department: 2167)
Land vehicles
Wheeled
Occupant propelled type
C188S275000
Reexamination Certificate
active
06267400
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the field of bicycle suspensions. More particularly, the invention relates to a damping enhancement system for a bicycle.
2. Description of the Related Art
For many years bicycles were constructed using exclusively rigid frame designs. These conventional bicycles relied on air-pressurized tires and a small amount of natural flexibility in the frame and front forks to absorb the bumps of the road and trail. This level of shock absorption was generally considered acceptable for bicycles which were ridden primarily on flat, well maintained roads. However, as “off-road” biking became more popular with the advent of All Terrain Bicycles (“ATBs”), improved shock absorption systems were needed to improve the smoothness of the ride over harsh terrain. As a result, new shock absorbing bicycle suspensions were developed.
Two such suspension systems are illustrated in
FIGS. 1 and 2
. These two rear suspension designs are described in detail in Leitner, U.S. Pat. No. 5,678,837, and Leitner, U.S. Pat. No. 5,509,679, which are assigned to the assignee of the present application. Briefly,
FIG. 1
illustrates a telescoping shock absorber
110
rigidly attached to the upper arm members
103
of the bicycle on one end and pivotally attached to the bicycle seat tube
120
at the other end (point
106
).
FIG. 2
employs another embodiment wherein a lever
205
is pivotally attached to the upper arm members
203
and the shock absorber
210
is pivotally attached to the lever
205
at an intermediate position
204
between the ends of the lever
205
.
There are several problems associated with the conventional shock absorbers employed in the foregoing rear suspension systems. One problem is that conventional shock absorbers are configured with a fixed damping rate. As such, the shock absorber can either be set “soft” for better wheel compliance to the terrain or “stiff” to minimize movement during aggressive pedaling of the rider. However, there is no mechanism in the prior art which provides for automatic adjustment of the shock absorber setting based on different terrain and/or pedaling conditions.
A second, related problem with the prior art is that conventional shock absorbers are only capable of reacting to the relative movement between the bicycle chassis and the wheel. In other words, the shock absorber itself has no way of differentiating between forces caused by the upward movement of the wheel (i.e., due to contact with the terrain) and forces caused by the downward movement of the chassis (i.e., due to movement of the rider's mass).
Thus, most shock absorbers are configured somewhere in between the “soft” and “stiff” settings (i.e., at an intermediate setting). Using a static, intermediate setting in this manner means that the “ideal” damper setting—i.e., the perfect level of stiffness for a given set of conditions—will never be fully realized. For example, a rider, when pedaling hard for maximum power and efficiency, prefers a rigid suspension whereby human energy output is vectored directly to the rotation of the rear wheel. By contrast, a rider prefers a softer suspension when riding over harsh terrain. A softer suspension setting improves the compliance of the wheel to the terrain which, in turn, improves the control by the rider.
Accordingly, what is needed is a damping system which will dynamically adjust to changes in terrain and/or pedaling conditions. What is also needed is a damping system which will provide to a “stiff” damping rate to control rider-induced suspension movement and a “soft” damping rate to absorb forces from the terrain. Finally, what is needed is a damping system which will differentiate between upward forces produced by the contact of the wheel with the terrain and downward forces produced by the movement of the rider's mass.
SUMMARY OF THE INVENTION
A bicycle shock absorber for differentiating between rider-induced forces and terrain-induced forces comprising: a first fluid chamber having fluid contained therein; a piston for compressing the fluid within the fluid chamber; a second fluid chamber coupled to the first fluid chamber by a fluid communication hose; and an inertial valve disposed within the second fluid chamber, the inertial valve opening in response to terrain-induced forces and providing communication of fluid compressed by the piston from the first fluid chamber to the second fluid chamber; and the inertial valve not opening in response to rider-induced forces and preventing communication of the fluid compressed by the piston from the first fluid chamber to the second fluid chamber.
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Fischer Andrew J.
Knobbe Martens Olson & Bear LLP
Olszewski Robert P.
Specialized Bicycle Components, Inc.
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