Boots – shoes – and leggings – Boots and shoes – Occupational or athletic shoe
Reexamination Certificate
2000-04-18
2002-11-12
Kavanaugh, Ted (Department: 3728)
Boots, shoes, and leggings
Boots and shoes
Occupational or athletic shoe
C036S103000, C036S144000
Reexamination Certificate
active
06477793
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of cycling footwear, and more particularly to a cycling shoe that is configured to improve a cyclist's leg posture when pedaling.
2. Description of the Related Art
FIG. 1
is a schematic partial front view of a typical human foot
100
having a hindfoot bone structure
102
and a forefoot structure consisting of a number of metatarsal bones
104
. The alignment of the foot
100
is depicted while in a neutral (i.e., natural or resting) posture relative to a horizontal axis
106
and a vertical axis
108
. The metatarsal bones
104
of the forefoot are shown tilted at an angle a with respect to the horizontal
106
while the hindfoot
102
is generally aligned along the vertical axis
108
. This illustrates the natural “varus” tilt of the forefoot that is observed in 80%-90% of human feet while in the neutral posture. In other words, most of the human population has a slight natural tilt of the forefoot while the foot is at rest, as shown in FIG.
1
. The varus tilt is typified by an elevated medial portion or instep of the foot, and a lowered lateral foot portion. In most persons, the natural varus angle is about 1.5°-5°.
FIG. 2
illustrates the effect of a varus forefoot on the motion and geometry of a bicycle rider's leg while pedaling a bicycle. A right leg
200
is shown with the foot
100
positioned on a pedal
202
that is situated horizontally, i.e. parallel to a flat ground surface. The right leg
200
also consists of an ankle joint system
204
, a tibia
206
, a fibula
208
, a knee joint
210
, a femur
212
, a hip joint
214
, and a pelvic bone
216
. When the rider presses down on the pedal
202
, the forefoot
104
is made to lay flat across the horizontal pedal
202
, and the ankle joint system
204
responds by rotating the lower leg (tibia
206
and fibula
208
) and tilting it in the medial direction. The femur
212
likewise tilts medially to follow the lower leg, and the rider assumes the “knock-kneed” posture shown in
FIG. 2
, during the downstroke portion of a pedaling motion. Although the varus tilt of the forefoot is typically at a very small angle (1°-2° in most people) the effect of this angle is multiplied by the length of the tibia
206
to create a significant and problematic deflection at the knee joint
210
.
This leg posture is undesirable to a cyclist for several reasons. First, it can be a source of pain in the knee because the forced rotation of the lower leg imparts an axial torque stress on the knee
210
, which cannot tolerate a large degree of axial torque. The torque stress is applied to the knee in combination with the repetitive, high-force knee flexion and extension observed when cycling, and thus can cause a rider to experience knee-joint pain that builds up over time. Furthermore, a cyclist typically experiences a loss of pedaling power when employing the leg posture shown in FIG.
2
. Because the rider typically pulls up on the pedal
202
(via a toe clip or cleat system as discussed in greater detail below) during the upstroke portion of a pedaling motion, the leg
200
straightens out as the forefoot
104
is no longer forced against the horizontal pedal surface
202
. The resulting alternation between medial bending and straightening of the leg
200
(as the leg
200
repeatedly progresses through downstroke and upstroke) causes the knee
210
to trace out a vertically-oriented oval pattern
218
shown in FIG.
2
. This back-and-forth lateral motion of the knee while cycling represents a high degree of wasted motion and energy for the cyclist. The result is faster onset of fatigue and erosion of the rider's capability to apply power to the pedal
202
.
FIGS. 3 and 4
depict the use of a wedge
300
to compensate for the natural varus forefoot posture. With the wedge
300
situated between the pedal
202
and forefoot
104
, the leg
200
can assume the straight posture shown in
FIG. 4
during both downstroke and upstroke, as the ankle joint, lower leg and femur no longer need to compensate for a deviation of the forefoot
104
from its natural varus posture. Thus the knee
210
traces out the desired straight-line pattern
220
as the rider pedals, with a minimum of the wasted motion, power loss, pain and fatigue associated with the poor leg posture depicted in FIG.
2
.
FIGS. 5A and 5B
depict a well-known pedal system
500
that includes a pedal
502
having a binding mechanism
504
that can receive a cleat
506
attached to the bottom of a cycling shoe
508
worn by the rider on each foot. The cycling shoe
508
has a relatively rigid outsole
510
, and the cleat
506
is usually attached to the sole
510
under the ball of the rider's foot. Typically, each pedal
502
has contact surfaces
512
on either side of the binding mechanism
504
that contact the shoe outsole
510
when the rider pushes down on the pedal
502
, to provide a wider shoe-to-pedal contact area and prevent the concentration of pressure under the rider's foot. This pedal system
500
provides superior cycling performance compared to pedals having toe clips or no foot attachment at all. This is because when “locked in” to the pedal
502
with the cleat
506
, the rider can push or pull on the pedal
502
in virtually any direction as desired during the pedaling stroke, with minimal loss of power due to poor foot-pedal coupling. Thus with a cleat-and-pedal system the rider can apply a greater amount of power to the pedals over a larger portion of the pedaling stroke.
FIG. 5C
shows a variation of the cleat-and-pedal system used with a mountain-bike shoe
550
. The mountain-bike shoe
550
is similar in many respects to the standard or road-bike shoe
508
discussed above, with the addition of tread portions
552
on either side of the cleat
506
and elsewhere on the outsole
510
. The tread portions
552
facilitate walking with or portaging a bicycle as is often necessary when cycling off-road. To prevent undue wear of or damage to the cleat
506
, the tread portions
552
are made sufficiently tall to create a gap or clearance
554
between the cleat
506
and a ground surface
556
. The clearance
554
assists in protecting the cleat
506
from damaging contact with a hard ground surface such as rocks, gravel or pavement as the rider walks in the shoes
550
.
U.S. Pat. No. 5,860,330 to Code et al. teaches several embodiments of a system for incorporating varus-angular compensation into a cleat-and-pedal system. The first embodiment, depicted schematically in
FIGS. 6A-6B
, consists of one or more angled shims
600
that are placed between the outsole
510
of the rider's shoe
508
and the cleat
506
. With the shims
600
installed, the cleat
506
is tilted with respect to the shoe outsole
510
so that when the rider mates the tilted cleat
506
with the pedal
502
, the tilted cleat
506
is supposed to compensate for the varus angle in a rider's foot and promote the desired leg posture as shown in FIG.
4
.
The shim system suffers from several drawbacks. First, when the cleat
506
is mated with the pedal
502
, the angle created between the cleat
506
and the outsole
510
by the shim
600
prevents the outsole
510
from abutting both of the contact surfaces
512
of the pedal
502
(see FIG.
6
B). Thus the contact area between the shoe
508
and the pedal
502
is reduced, which concentrates pressure upon the lateral aspect of the rider's foot when he bears down on the pedal
502
. Such a pressure concentration causes foot discomfort and ultimately reduces the efficiency of power transfer to the pedal
502
.
Furthermore, as seen in
FIG. 7
the shim system taught by Code creates difficulty when used with the mountain-bike shoe
550
. With the shim
600
in place, the lower edge of the cleat
506
extends very close to the ground surface
556
, or even protrudes beyond the plane defined by the bottom edges of the tread portions
552
. This arrangement exposes the cleat
506
to damage and wear
Bird Carl
Fryer Luke
Pruitt Andrew L.
Kavanaugh Ted
Knobbe Martens Olson & Bear LLP
Specialized Bicycle Components, Inc.
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