Clap skate with spring and cable biasing system

A skate primarily intended for speed skating. The skate is of the clap type wherein the blade is pivotally movable with respect to the boot. A coupling assembly includes top and bottom linkages pivotally attached to one another and is disposed to permit pivotal movement between the blade and the boot. The upper linkage is attached to the boot and the lower linkage is attached to the blade. A biasing arrangement moves the linkages into a closed position. The biasing arrangement includes a spring, a pulley, and a roller. The spring attached at its fore end to the bottom linkage. The cable is attached to the aft end of the spring, is guided around the pulley, and is attached to the top linkage. A significant portion of the biasing arrangement is shielded within the bottom linkage for protection and to provide a compact and effective design. The orientation and features of the biasing arrangement and guide surfaces of the linkages minimizes torsional forces on the coupling assembly, minimizes wear, and increases spring tension forces.

FIELD OF THE INVENTION 
The present invention relates to skates primarily used in speed skating. 
More specifically, the present invention relates to "clap skates" which 
are skates that permit the skater to pivot the shoe portion of the skate 
with respect to the ground or ice engaging portion to enhance performance. 
BACKGROUND OF THE INVENTION 
In the sport of ice speed skating, the overwhelming majority of skaters for 
many years have used a type of skate where the foot retaining portion 
(i.e., the boot) is fixedly mounted to an elongated blade by forward and 
rearward pedestals. To use these conventional skates effectively, a skater 
must learn to maintain his ankle in a rigid position while placing 
pressure on his heel and pointing his toes skyward to keep the blade 
parallel to the ice during stride and obtain relatively long strides. 
However, skating in this fashion restricts the ankle's role in propulsion, 
virtually omits the power of the ankle and the calf muscles from the 
stride, and causes the blade to leave the ice before full leg extension is 
complete. Further, this conventional method of skating causes the leg 
muscles to be tense through most of the stride, creating a stiff, robotic 
effect that inhibits optimum performance. 
A "clap skate" differs from a conventional skate in that skater's boot is 
pivotable forwardly with respect to its blade about a pivot axis 
transverse to the length of the blade. Examples of existing clap skates 
are shown in FIGS. 1-2, FIG. 3, and in European Patent Application No. 
192,312. In clap skates, the forward portion of the boot is pivotally 
attached to the blade while a rearward portion of the boot can be tilted 
forwardly as it moves about an established front pivot axis. A pivot and 
biasing arrangement allows the heel of a skater's boot to rise and fall 
and biases the blade with respect to the boot, which keeps the blade in 
contact with the ice for the length of the skater's stride. These pivot 
and biasing arrangements allow the skater to take longer and more fluid 
strides, and allows all the leg muscles to work in a fluid, more efficient 
manner, resulting in an economy of motion and faster skating times. 
The separating heel design of the clap skates also allows the skater to add 
the power of his calf muscles to his stride, while keeping the blade on 
the ice. In essence, it provides an extra set of muscles for the skater to 
use. The skater's legs can therefore act more like that of a jumper, who 
flexes the ankle, pushing off the heel, then the ball of the foot and then 
the toes. This makes the strides longer and much more powerful. 
There are two ways to use clap skates, either of which achieves benefits 
over the conventional skates. One way is for the skater to sit just as 
deep as he ordinarily would, but get a longer push. The other alternative 
is for the skater to sit higher, but get the same push. Sitting higher is 
advantageous because it almost always results in better endurance. 
One prior art clap skate design is shown in FIGS. 1 and 2. Skate 10 
includes a boot 12 and a blade 14 which is held in an elongated tubular 
blade holder 15. The bottom of the boot 12 includes fore and aft mounts 
16, 18, respectively. Boot 12 is coupled to an upper frame member 20 by 
attaching the bottom of mounts 16, 18 to upper frame member 20. 
A pair of laterally spaced parallel brackets 22 are attached to blade 
holder 15. A pin 24 extends through parallel holes in the brackets 22 and 
a hole in the forward portion of the upper frame member 20. The rearward 
portion of the upper frame member 20 is not attached to the blade 14 so 
that the upper frame member 20 and the boot 12 can pivotally move with 
respect to the blade 14 about the axis of the pin 24. The upper frame 
member 20 is laterally guided with respect to the blade 14 and blade 
holder 15 only at its fore end by opposing inner wall surfaces of 
laterally spaced parallel brackets 22. 
On both the lateral and medial sides of the blade 14, a spring 26 is 
connected at its ends to projections 28, 30 on the parallel brackets 22 
and the upper frame member 20 respectively. Springs 26 are pretensioned so 
that the blade 14 and blade holder 15 are biased towards a closed position 
as shown in FIG. 1. As the skater flexes his ankle during stride, the boot 
12 and upper frame member 20 pivots with respect to the blade 14 and blade 
holder 15 to move from the closed position, as shown in FIG. 1, to an open 
position, as shown in FIG. 2. The springs 26 return the blade 14 and blade 
holder 15 to the closed position when the blade 14 is lifted off the ice. 
A stop 32 is located on the top of an aft pedestal mount 33 which is 
attached to the blade holder 15 aft of brackets 22 so that the upper frame 
member 20 stops in a predetermined position. 
Another prior art clap skate design is shown in FIG. 3 and is designated by 
reference numeral 40. The primary difference between skate 40 of FIG. 3 
and skate 10 of FIGS. 1 and 2 is that the coil springs 26 of skate 10 have 
been eliminated, and a torsional spring 42 has been added adjacent the 
front pivot axis 44. In addition, in lieu of stop 32, a hollow cone 46 is 
mounted on the rearward portion of the boot 47 and interfaces with a cone 
shaped projection 48 mounted to the blade holder 49. 
While providing advantages over conventional fixed skates, these and other 
prior art clap skate designs include a number of drawbacks. Problems and 
drawbacks exhibited by prior art clap skates are related to the spring 
biasing systems used and other aspects of the skates. With respect to the 
spring biasing systems, drawbacks may reside in low return spring rates 
and/or erratically controlled spring forces. Other problems and drawbacks 
include poor lateral stability between the boot and blade which can result 
in excessive and undesirable torques on the hinge and blade, especially 
during cross-over strides when the skater is going around turns. Further, 
none of the prior art skate designs provide structure permitting simple 
adjustment of the biasing force. Moreover, the structural arrangements in 
the prior art skates that are used to stop the members as the blade moves 
to the closed position create a single point shock force which is felt by 
the skater. A few examples of the drawbacks are described below with 
respect to skates 10 and 40 of FIGS. 1 and 2 and FIG. 3, respectively. 
In skate 10 of FIGS. 1 and 2, two springs 26 are used to apply the biasing 
force to the blade and blade holder to move them to the closed position. 
However, this design has drawbacks associated with the spring design and 
interaction with other elements of the skate. As can be seen from FIGS. 1 
and 2, the spring forces are directly applied to the upper frame member 20 
at projections 30--a point located slightly less than halfway from the 
pivot axis 24 to the aft end of the upper frame member 20 and also 
slightly less than halfway from the pivot axis 24 to the connection point 
between aft boot mount 18 and the upper frame member 20. This feature, in 
combination with the feature that the upper frame member 20 is laterally 
guided with respect to the blade 14 and blade holder 15 at its fore end by 
opposing inner wall surfaces of laterally spaced parallel brackets 22 and 
at its rear end only during the very end of its pivotal motion towards its 
closed position by opposing side surfaces of stop 32, causes high lateral 
torsional forces to be applied at the hinge, i.e., pin 16 and laterally 
spaced parallel brackets 22, whenever the force applied to the upper frame 
member 20 by the skater is not exactly coincident with blade 14. These 
lateral forces are undesirable because they cause the aft end of the upper 
frame member 20 to be laterally displaced from the longitudinal axis of 
the blade 14 causing inefficient transfer of the skater's thrusting force 
to the blade and poor lateral stability. It may also lead to damage of the 
laterally spaced parallel brackets 22 or the pin 24. Moreover, these 
undesirable forces are the highest at the most critical times of race, 
when the skater is going around turns and crossing-over--where the races 
are most often won and lost. 
Another drawback in this design is that the connection points between the 
ends of the springs 26 do not take full advantage of the length that the 
spring could theoretically extend. This results in a low spring return 
rate and/or the use of unnecessarily large springs. Further, there is no 
way for the skater to adjust the spring return rate without having to 
replace the spring. This is undesirable because skaters would have to 
carry a collection of springs if they wanted to gain a competitive 
advantage by adjusting the spring return rate due to conditions of the ice 
surface. 
Yet another drawback of this design is that two springs are required to 
produce a balanced biasing force along the longitudinal axis of the blade. 
Further, as the springs are medially and laterally spaced from the central 
longitudinal axis of the blade, their inherent positioning exposes the 
springs and makes them especially susceptible to physical damage in use 
and in transportation. 
In the design as shown in FIG. 1, when the blade 14 is in the closed 
position, the skater's thrust force is transferred to the blade 14 and 
blade holder 15 in only two small areas--at the hinge and at the stop 32. 
This results in the skater's thrust force being transferred at high and 
possibly uneven concentrations. Moreover, because stop 32 includes only a 
small surface to apply the stopping force, this stopping force is highly 
concentrated. This can lead to repetitive shock forces being absorbed by 
the skater on his heel and a louder distracting clapping force generated 
each time the blade 14 and blade holder 15 moves to their closed position. 
Skate 40 of FIG. 3 includes many of the same or similar drawbacks and 
exhibits many of the same or similar undesirable qualities as skate 10 
shown in FIGS. 1 and 2. Spring 42 of skate 40 applies the biasing force to 
the blade and blade holder to move them to the closed position. However, 
the spring force is applied immediately adjacent the pivot pin by torsion 
spring 42. This results in undesirable lateral torsional forces which are 
even greater that those of skate 10 of FIGS. 1 and 2 because the biasing 
force is applied at or immediately adjacent the hinge pin.44. As described 
above, this can cause inefficient transfer of the skater's thrusting force 
to the blade and poor lateral stability, and it may also lead to damage of 
the laterally spaced parallel brackets 22 or the pin 24. Further, the 
torsional spring 42 does not take full advantage of the length that the 
spring could theoretically extend. There is also apparently no way for the 
skater to adjust the spring return rate without having to replace the 
spring. Skate 40 is also similar to skate 10, in that the skater's thrust 
force is transferred to the blade 14 and blade holder 15 in only two small 
areas resulting in the skater's thrust force being transferred at high and 
possibly uneven concentrations, and a highly concentrated stopping force. 
SUMMARY OF THE PRESENT INVENTION 
In view of the foregoing, it is a principal object of the present invention 
to provide an improved clap skate that incorporates all advantages 
exhibited by clap skates including increased stride length and use of 
lower leg muscles, and overcomes drawbacks and disadvantages associated 
with prior art clap skates. 
The skate according to the present invention includes an element for 
holding a foot of a skater and a supporting surface engaging assembly for 
contacting a supporting surface and transferring a propulsion force 
applied by the skater from the foot holding element to the supporting 
surface. The skate also includes an assembly coupling the foot holding 
element and the supporting surface engaging assembly such that the foot 
holding element and the supporting surface engaging assembly are pivotally 
movable with respect to each other to move the supporting surface engaging 
assembly between open and closed positions relative to the foot holding 
element. The supporting surface engaging assembly is biased by a biasing 
device to move it into its closed position. The biasing device includes a 
spring and a cable, both having first and second ends. The first end of 
the spring is attached to one of the foot holding element and the 
supporting surface engaging assembly, while the second end of the spring 
is attached to the first end of the cable. The second end of the cable is 
attached to the other of the foot holding element and the supporting 
surface engaging assembly. The biasing device according to the present 
invention is compact and easily adjustable. It is also shielded from 
external forces and aligned on center with the movement of the upper 
linkage of the coupling assembly. The spring and fore portion of the cable 
are generally horizontally disposed and parallel with the longitudinal 
axis of the supporting surface engaging assembly and the bottom linkage of 
the coupling assembly. 
The biasing device according to the present invention evenly applies and 
distributes a high spring force to the foot holding element, the coupling 
assembly and the supporting surface engaging assembly. The biasing device 
also includes a cable length adjustment mechanism for adjusting the 
effective length of the cable and the biasing force. 
The coupling assembly includes first and second linkages made from 
different materials and pivotally attached to one another. The first 
linkage includes an arcuate stopping surface for limiting the movement of 
and guiding the second linkage to reduce torsional forces experienced by 
the linkages and the pivot arrangement. 
These and other objects and features of the invention will be apparent upon 
consideration of the following detailed description of preferred 
embodiments thereof, presented in connection with the following drawings 
in which like reference numerals identify like elements throughout.

DETAILED DESCRIPTION 
In the present invention, as pictured in FIGS. 4-11, a clap skate is 
designated generally by reference numeral 50. Skate 50 is preferably of 
the type used for speed skating and is of the clap skate type, i.e., where 
skater's boot is pivotable forwardly with respect to its supporting 
surface engaging structure, e.g., its blade, about a pivot axis transverse 
to its ground supporting structure. In sum, the skate 50 includes a boot 
52 or a foot holding element for securely holding a skater's foot, a 
supporting surface engaging unit 53, and an articulating coupling and 
biasing system 56 which couples the boot 52 to the supporting surface 
contacting propulsion unit 53, permits the skater to forwardly pivot his 
foot with respect to the supporting surface contacting propulsion unit 53, 
and automatically returns the supporting surface contacting propulsion 
unit 53 to a closed position with respect to the boot 52 in the absence of 
an applied force by the skater. 
In FIGS. 4-11 and in the majority of the following specification, skate 50 
is primarily shown and described as being adapted for ice skating. 
Accordingly, supporting surface engaging unit 53 is depicted and described 
as being a blade assembly 54 having a blade or runner 58 and a blade 
holder 60, and is intended to contact an ice surface and transmit a force 
to the ice surface to propel the skater. However, the current invention is 
not limited to such an application, and the skate may be adapted for an 
in-line wheeled skate. In such an event, supporting surface engaging unit 
would include a chassis having a longitudinal frame and a plurality of 
in-line wheels each rotatably mounted about a respective axis transverse 
to the longitudinal frame, and would be intended to contact hard surfaces 
normally used for in-line skating, e.g., cement or concrete. This 
embodiment is shown in FIG. 12 and described hereinafter. 
As shown in FIGS. 4-11, articulating coupling and biasing system 56 
preferably includes a top linkage 62, a bottom linkage 64, and a biasing 
return system 66 which biases the top linkage 62 and bottom linkage 64 
into a closed position with respect to each other. Top linkage 62 is 
fixedly mounted to boot 52 and bottom linkage 64 is fixedly mounted to 
blade 58 such that the articulating coupling and biasing system 56 permits 
pivotal movement between the boot 52 and the blade 58 and biases the blade 
58 into a predetermined and closed position with respect to the boot 52. 
More specifically, top linkage 62 includes a top wall 61 having fore and 
aft longitudinal slots 67 and 68 permitting screws, e.g. screw 138, to be 
screwed into tapped holes in fore and aft mounts 137, respectively, on the 
bottom of boot 52. This physically attaches the top linkage 62 to boot 52. 
The longitudinal slots 67 and 68 permit top linkage 62 to be attached to 
boots of varying size. This arrangement also permits removal and 
replacement of boot 52 without the need to discard the entire skate. As 
can be seen in FIG. 4, top wall 61 of top linkage 62 has a slight rise in 
it along the longitudinal axis as it extends rearwardly. This compensates 
for a slight increase in height, e.g., 1 cm., between the fore and aft 
mounts on boot 52 which is common on many boots. 
Bottom linkage 64 preferably includes a bottom wall 71 having fore and aft 
slots, not shown, for removably awing articulating coupling and biasing 
system 56 to blade assembly 54. Blade assembly 54 includes fore and aft 
mounts 63 and 65 which are welded, e.g., silver soldered, to the top of 
blade holder 60. The fore and aft mounts 63 and 65 are tapped such that 
common hardware, e.g., screws, can extend through the fore and aft slots 
in bottom linkage 64 to attach articulating coupling and biasing system 56 
to blade assembly 54. This arrangement is beneficial as the repeated 
sharpening of the blade 58 causes it to wear down, and this arrangement 
permits removal and replacement of blade assembly 54 without the need to 
discard the entire skate. In the preferred embodiment as shown, bottom 
linkage 64 is substantially parallel to blade 58 and blade holder 60. 
Adjacent their forward ends, top linkage 62 and bottom linkage 64 are 
pivotally mounted to each other such that bottom linkage 64 and blade 
assembly 54 are pivotally movable with respect to boot 52 about an axis 69 
transverse to the longitudinal axes of blade 58, blade holder 60, and 
linkages 62 and 64. This pivotal coupling preferably includes oil 
impregnated cylindrical flange bearings 70 located in both ends of a 
cylindrical transverse bore 72 in the front of bottom linkage 64. Top 
linkage 62 includes left and right opposing side walls 73, the 
forward-most ends of which include forwardly extending ears 74 having 
aligned transverse holes 76 therein. Holes 76 in the inner surfaces of 
ears 74 are aligned with holes 78 in flange bearings 70, and a 
through-bolt 80 with threads at its end extends through the aligned holes 
76 and 78. A nylon lock nut 82 is threaded onto bolt 80 to keep it 
retained in its position. This pivotal connection exhibits a low 
coefficient of friction because the inner cylindrical surface 83 of 
bearings 70 minimizes friction and wear between bolt 80 and bearings 70 
and the side bearing surfaces 84 of bearings 70 minimizes friction and 
wear between ears 74 and bottom linkage 64. Nylon washers, not shown, are 
placed between the outer sides of ears 74 and the head of the bolt 80 and 
the lock nut 82, respectively, to further minimize the friction associated 
with bolt 80 as top linkage 62 moves with respect to bottom linkage 64. 
The side walls 92 of the bottom linkage 64 guide the side walls 73 of the 
top linkage 62 as it moves between open and closed positions and form a 
stop to limit the relative movement of the linkages 62 and 64 as they move 
into the closed position. As illustrated in FIGS. 6 and 8, the side walls 
92 of the bottom linkage 64 have reduced wall sections 121 that are 
recessed along their length to provide lateral guide surfaces 122 and a 
bottom ledge 124. Lateral guide surfaces 122 provide lateral guides for 
the inner surfaces of side walls 73 of top linkage 62. The forward-most 
portion of the lateral guide surfaces 122 guide the side walls 73 for the 
entire range of travel and the effective guiding surface area of guide 
surfaces 122 increases as the blade assembly 54 moves into the closed 
position. Accordingly, this arrangement enhances the life of the pivot 
assembly and prevents high transverse torsional forces between the 
linkages because the torsional forces are transferred between the boot 52 
and the blade 58 via the elongated guide surfaces 122 and the side walls 
73. 
Ledge 124 forms a stop for top linkage 62 and engages the bottom edge of 
side walls 73 to prevent further relative movement as the unit returns to 
its closed position. As shown in the drawings, ledge 124 has an arcuate 
profile along its length and is shaped substantially complimentary to the 
bottom edge of side walls 73. This arrangement provides an elongated 
curved stopping area over the length of the bottom linkage 64, and 
provides for an even contact area and energy transfer between the boot 52 
and the blade assembly 54 as they move relative to one another. Moreover, 
the elongated nature of the ledge 124 results in more evenly distributed 
forces over the length of ledge 124. This helps to distribute some of the 
stopping forces to the front of the boot 52 and reduces the highly 
concentrated loads and shock forces normally transmitted at the heel of 
the boot 52. 
In a preferred embodiment, bottom linkage 64 is made from a strong 
machinable plastic while top linkage 62 is made from aluminum. This 
material combination provides a low coefficient of friction between the 
linkages to reduce wear, while simultaneously providing high strength 
qualities. Moreover, the combination of materials provides a low clapping 
sound to reduce distractions. Further, the top linkage 62 preferably 
includes cut-out portions 126 which reduces the weight of the skate 50. 
Absent a thrust force applied by a skater when the skater pivots his ankle, 
biasing return assembly 66 places the blade assembly 54 in the closed 
position. Biasing return assembly 66 utilizes a spring 86, a cable 88, and 
a pulley 90 to accomplish this biasing force. As shown in FIGS. 7 and 9, 
spring 86 is disposed in a channel 87 created between left and right 
opposing side walls 92 of bottom linkage 64. Spring 86 includes a hook 94 
at its fore end which is inserted into a hole 95 in a transverse rib 96 
disposed between opposing side walls 92. The spring 86 hooks around 
transverse rib 96 between the hole 95 and the top of the rib 96. The aft 
end 98 of spring 86 is fixedly attached to the fore end of cable 88 in any 
suitable manner. 
Pulley 90 is a cylindrical spool 101 having a recessed groove 100 and a 
cylindrical bore hole 103 which extends the length of the spool 101. 
Cylindrical bore hole 103 of spool 101 is placed in alignment with 
transverse holes 102 adjacent to the aft end of left and right side walls 
92 of bottom linkage 64. A through-bolt, not shown, with threads at its 
end, extends through the aligned holes 102 in side walls 92 of bottom 
linkage 64 and the hole 103 of spool 101. The through-bolt provides a 
transverse axis 105 for the spool's rotation. A nylon lock nut, not shown, 
is threaded onto the bolt to keep it retained in its position. To reduce 
fiction and provide a reliable system, the spool 101 is preferably 
comprised of brass which is a high strength, low friction material. 
Cable 88 extends rearwardly from spring 86 into the groove 100 of pulley 
90, around its transverse rotatable axis 105, and upward to the top 
linkage 62 where it is attached. Groove 100 retains cable 88 in lateral 
alignment as the blade assembly 54 repetitively moves with respect to boot 
52. To attach the end of cable 88 to top linkage 62, a threaded hole 106 
is formed through top wall 61 and the cable 88 is routed through the hole 
106. A tightening screw, schematically designated by reference numeral 
108, is screwed into hole 106 where it bites into cable 88 and pinches it 
against the walls of the hole 106 to form the functional end of the cable 
88. Excess cable can be cut, capped, wrapped, or otherwise manipulated so 
not as to interfere with the operation of the device. The tension can be 
adjusted by loosening the screw 108, adjusting the length of cable 88 
between the pulley 90 and hole 106 to the desired length, and 
re-tightening the tightening screw 108 to form a different effective end 
of the cable 88. The end portion of the cable 88 can be marked by lines or 
different colors so the skater knows the relative pre-set tension levels. 
The adjustable nature of the tension force permits users to adjust the 
spring tension force based on the ability of skater and the conditions of 
the ice surface. The cable 88 is preferably made from a TEFLON (i.e., 
polytetrafluoroethylene) impregnated material, similar to what is used in 
the biking industry. 
However, in lieu of the tightening screw and threaded hole arrangement 
described above, any other connection method may be used, whether 
adjustable or not, although it is the adjustability feature is preferred. 
One such alternative design is shown in FIG. 11. In this cable length 
adjustment device, top linkage 130 includes an elongated threaded bore 131 
having a longitudinal axis parallel to the longitudinal axis of the top 
linkage 130. A threaded cable ferrule 132 includes an elongated central 
bore 133 and an enlarged end section 134 with a recessed inner surface 
135. The rear end of cable 88 has an enlarged or butted section 136 which 
is wider than the diameter of elongated central bore 133. Butted section 
136 of cable 88 bears against recessed inner surface 135 and keeps spring 
86 in a pretensioned position. By turning the ferrule 132 within elongated 
threaded bore 131, cable 88 can be pulled tighter or loosened against the 
spring 86 to adjust the biasing force. FIG. 11 also shows the relationship 
between boot 52, the aft mount 137 on boot 52, and mounting hardware 138 
used to attach the top linkage to the boot 52. 
As can be seen from the figures, spring 86 and the fore portion of cable 88 
are disposed in channel 87 between the side walls 92 of bottom linkage 64. 
This shields the spring 86 and fore portion of cable 88 from physical 
damage during transportation and use. Further, the channel and positioning 
of the spring 86 and the fore portion of cable 88 in a substantially 
horizontal orientation inside channel 87, which is also substantially 
horizontal, creates a highly compact and effective arrangement. As the 
coupling of the cable 88 between the pulley 90 and the top linkage 62 is 
near the aft of the skate, farthest from transverse axis 69, the spring 86 
can be displaced a relatively large amount. This permits the unit to have 
a high spring tension force and to have the spring tension force be 
applied in an even and smooth manner. Moreover, because the biasing force 
is at the rear of the linkages and behind the stopping ledges, the 
torsional forces will further be minimized. 
In use, the spring 86, cable 88, and pulley 90 arrangement biases the blade 
assembly to the closed position, as shown in FIGS. 4 and 5. When the 
skater thrusts his leg outward and pivots his ankle near the end of his 
stride, the thrusting force will move towards the front of the blade 58 
until it shifts front of transverse axis 69. Upon the thrusting force 
moving forward of transverse axis 69, blade assembly 54 and bottom linkage 
64 pivot with respect to top linkage 62 and boot 52 against the biasing 
force to keep the blade 58 on the ice for the entire length of the 
skater's stride. When the skater picks his skate up to ready for the next 
stride, the thrusting force transferred between the boot 52 and the ice, 
via blade 58, is removed, and the biasing force applied by spring 86 and 
cable 88 returns the blade assembly 54 to the closed position. 
An in-line roller skate featuring the previously described articulating 
coupling and biasing system is shown in FIG. 11. Accordingly, the primary 
difference between this skate 150 and skate 50 of FIGS. 4-10, is the 
supporting surface contacting propulsion unit, which is now a chassis 152 
and wheels 154, in lieu of the blade assembly. In a manner well known, 
wheels 154 are mounted for rotation about individual transverse axes 
perpendicular to the longitudinal axis of chassis 152. Chassis 152 is 
preferably mounted to bottom linkage 64 by conventional hardware. In use, 
skate 150 behaves similar to skate 50 of FIGS. 4-10. 
While particular embodiments of the invention have been shown and 
described, it is recognized that various modifications thereof will occur 
to those skilled in the art. Therefore, the scope of the herein-described 
invention shall be limited solely by the claims appended hereto.