Abstract:
A detachable pedal assembly including an automatic release mechanism that is positioned approximately between the pedal and crank arm is disclosed. The detachable pedal assembly in one embodiment comprising an axle assembly including thrust bearing and threads to engage the crank, a binding assembly including a pedal to which the cyclist applies force and clasp that detachably receives the thrust bearing, and a force-sensitive locking means that holds the binding assembly in operational engagement to the axle assembly until a predetermined force is applied, at which time the binding assembly automatically releases the axle assembly to permit the cyclist to dismount or avoid injury in an accident. The position of the release mechanism to the side of the binding assembly permits the binding assembly to be offset from the axle axis, thereby improving increased riding efficiency, lower aerodynamic drag, and increased turning clearance.

Description:
BACKGROUND  
         [0001]    The present invention relates to a detachable combination shoe-pedal assembly for use in cycling. More particularly, the invention relates to a pedal assembly that permits a cycling shoe-pedal assembly to operably engage and safely disengage the pedal crank arm of a bicycle or other pedal powered apparatus.  
           [0002]    Many modern bicycles, including those intended for road racing, are designed to transfer and convert the linear forces applied by the cyclist into rotational motion of the crank arm and sprocket. In conventional bicycles, the forces generated by the cyclist are exerted through the pedal assembly in the vertical direction when the pedal is depressed by the rider&#39;s foot as well as lifted on the upstroke. A popular configurations for road racing is the clipless pedal system comprising a pedal with a receptacle adapted to receive a cleat mounted in the sole of a special cycling shoes. This cleat snaps into the pedal receptacle allowing the cyclist to connect a shoe directly to the pedal, and indirectly to the crank arms, with ease. The cyclist&#39;s foot then disengages the pedal system by rotating or displacing the shoe in a predefined manner or under the force of an accident, for example.  
           [0003]    Although the clipless pedal system allows the operator&#39;s foot to quickly connect to and disconnect from the crank, the cleat and corresponding receptacle in prior art systems is located directly below the sole of the cycling shoe. The location of the cleat and receptacle below the cyclist foot detrimentally affect the performance in at least three ways: First, the prior art systems, which can be as much as an inch thick, reduce the ground clearance at the underside of the pedal, thereby reducing limiting the angle at which the bicycle may be simultaneously pedaled and turned. Second, the thickness of the cleat and receptacle system increases the riding height of the cyclist and the frame, thereby increasing aerodynamic drag and bicycle weight. Third, the force exerted by the foot of the cyclist is distributed over the relatively small area of the cleat which increases the pressure of the foot in immediate proximity to the cleat of the foot and causes discomfort to the cyclist.  
           [0004]    U.S. Pat. Nos. 5,586,472 to Lin, 5,440,950 to Tranvoiz, and 5,315,896 to Stringer disclose detachable pedal assemblies in which a portion of the release mechanism is located in proximity to the crank arm. In each of these patents, the pedal is mounted either directly or indirectly into the crack through the spindle. The pedal remains rotatably affixed to the crank until a linear force co-parallel to the axis of the spindle is applied. Although these prior art pedal assemblies may be quickly attached to and removed from the crank arm, manual intervention is required without which the pedal cannot be engaged or disengaged. Moreoever, these pedal assemblies are designed to facilitate the assembly and disassembly of the pedal in connection with the storage and transportation of the bicycle. These pedal assemblies do not include means to attach a cycling shoe to the pedal and are, therefore, entirely unsuitable for road racing applications where it is necessary to both press down and lift up the pedal.  
         SUMMARY  
         [0005]    The present invention overcomes the limitations of the prior art with a detachable pedal assembly in which the release mechanism is positioned adjacent to the axle that threadedly engages the bicycle pedal crank arm. Location of the release mechanism to the side of the pedal and away from the underside of the cyclist&#39;s foot allows (1) the rider to assume a lower riding position, thereby reducing the frame height and aerodynamic drag; (2) the bottom side of the pedal to be raised, thereby allowing for sharper turns of the bicycle; (3) the pedal to have a greater surface area, thereby reducing the pressure across the cyclist&#39;s foot; and (4) the rider visibility of the release mechanism during engagement, unlike prior art systems.  
           [0006]    In one embodiment of the present invention, the detachable pedal assembly is comprised of an axle assembly, binding assembly, and connecting means. The axle assembly is comprised of an axle adapted to threadedly engage the bicycle pedal crank arm. The binding assembly is comprised of a pedal through which the cycling shoe applies force to drive the bicycle. The connecting means is comprised of a bearing and releasable coupling means, the connecting means being substantially interposed between the pedal crank arm and the binding assembly in the lateral direction. Although the bearing and releasable coupling means may be affixed to either the axle assembly or the binding assembly, it is important that the releasable coupling means rigidly hold the binding assembly to the axle assembly until a force equal to or greater than a predetermined force threshold is applied, at which point the release coupling means responds by automatically disengaging the binding assembly from the axle assembly. In this manner, a cyclist may exert force on the pedal assembly without disengaging the pedal crank arm unless the cyclist chooses to disengage the binding assembly from the axle assembly. In some embodiments, the shoe-pedal assembly may be automatically disengaged from the bicycle crank if the cyclist befalls adverse circumstances.  
           [0007]    In some embodiments of the present invention are designed with offset between the pedal of the binding assembly and the axle assembly to position the ball of the cyclist&#39;s foot at the axis of the axle. Still other embodiments adapted primarily to bicycle road racing applications include shoe fastening means permitting the cycling shoe to be affixed to the pedal assembly, thereby allowing the cyclist to drive the bicycle by pushing against the pedal in the down stroke as well as pulling on the pedal during the upstroke. The shoe fastening means may be used in combination with a force-responsive locking means that determines the force necessary to release the binding assembly from the axle assembly.  
           [0008]    The shoe-pedal assembly in preferred embodiments is made to engage and disengage the axle mounted on the bicycle pedal crank assembly in the vertical direction, while other embodiments permit the binding assembly to engage and disengage the axle in the other directions or manners. The binding assembly may be made to alternatively engage or disengage the axle by means of one or more forces including rotational forces or linear forces applied in the horizontal or vertical plain. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is an exploded view of the detachable pedal assembly including the axle assembly, connecting means, and binding assembly of the present invention.  
         [0010]    [0010]FIG. 2 is a cross-sectional view in a vertical plane through the axis of the axle in the preferred embodiment of the detachable pedal assembly.  
         [0011]    [0011]FIG. 3 is an interior side view of the binding assembly of the preferred embodiment attached to the shoe.  
         [0012]    [0012]FIG. 4 is a view of the underside of the binding assembly and axle assembly, attached to the shoe and mounted into the crank arm, of the preferred embodiment.  
         [0013]    [0013]FIG. 5 is a front side view of the shoe with binding assembly, axle, and crank arm of the preferred embodiment in the locked position. 
     
    
     DETAILED DESCRIPTION  
       [0014]    The present invention pertains to a detachable pedal assembly permitting a cycling shoe to operably engage and safely and efficiently disengage the pedal crank arm of a bicycle or other pedal powered apparatus. The pedal assembly effectively transmits the forces exerted by the cyclist&#39;s shoe to the pedal crank arm, allowing the cyclist to both push down on the pedal as well as lift up on it so long as the forces are within a predetermined range. For safety purposes, the cyclist&#39;s shoe-pedal assembly may be released from the pedal crank when the forces reach an unsafe level as in an accident or collision, for example.  
         [0015]    The accompanying figures depict embodiments of the detachable pedal assembly of the present invention, and features and components thereof. With regard to means for fastening, mounting, attaching or connecting the components of the present invention to form the apparatus as a whole, unless specifically described otherwise, such means are intended to encompass conventional fasteners such as machine screws, machine threads, snap rings, hose clamps such as screw clamps and the like, rivets, nuts and bolts, toggles, pins and the like. Components may also be connected by friction fitting, or by welding or deformation, if appropriate. Unless specifically otherwise disclosed or taught, materials for making components of the present invention are selected from appropriate materials such as metal, metallic alloys, natural or synthetic fibers, plastics and the like, and appropriate manufacturing or production methods including casting, extruding, molding and machining may be used.  
         [0016]    Any references to front and back, right and left, top and bottom, upper and lower, and horizontal and vertical are intended for convenience of description, not to limit the present invention or its components to any one positional or spatial orientation.  
         [0017]    Referring to FIGS. 1 and 2, an exploded view and cross section of the detachable pedal assembly including the axle assembly, bearing, and binding assembly of the present invention are illustrated. The axle assembly  124  in this embodiment is comprised of an axle  102 , a bearing  103 , and an optional spacer  104 .  
         [0018]    The axle  102  is comprised of a pedal crank connecting portion  109  and a bearing connecting portion  110 . The crank connecting portion  109  preferably includes a standard thread pattern adapted to securely engage the corresponding threads  107  of the crank arm  106 . The bearing connecting portion  110  is characterized by a diameter substantially equal to the diameter of the inner surface  114  of the bearing  103  such that the axle  102  and bearing  103  are securely affixed to one another after installation of the bearing  103  and during operation of the bicycle. After installation, the bearing  103  preferably abuts a retainer  111  which, in this embodiment, is a circularly symmetric lip used to prevent the bearing  103  from disengaging the axle  102  in the direction away from the crank arm  106 . The retainer  111  preferably includes two parallel planar faces  111 A that adapted to receive a wrench used to apply the torque necessary to engage and disengage the threads of the crank connecting portion  109  to the crank arm  106 . In other embodiments, the bearing connecting portion  110  and bearing  103  may include threads, set screws, permanent welds, bonding agents, or friction fitting to prevent the unintended separation of the bearing  103  from the axle  102 .  
         [0019]    The bearing  103  represents any one of a number of alternative structures for providing a substantially friction free rotation of the binding assembly  101  relative to the axle  102 . In general, the bearing  103  includes an inner surface  114  and outer surface  113  that rotate relative to one another about the bearing axis that coincides in this embodiment with the axis of the axle  130 . The internal construction of bearings is well document and unnecessary for an understanding of the design, assembly and operation of the present invention.  
         [0020]    In the preferred embodiment, the bearing  103  is a sealed thrust bearing capable of withstanding rotational forces about the axle axis  130  as well as torsional forces exerted by the binding assembly  101  discussed in more detail below. Although aircraft quality bearings are suitable, the bearing used in the present invention is subjected to relatively low speeds, typically on the order of 120 rpm in this embodiment. One skilled in the art will recognize that other standard bearings and custom bearings including various ball bearings, baring faces, and lubricants may be equally suitable with appropriate modification to the axle  102  and binding assembly  101 .  
         [0021]    The detachable pedal assembly of the present invention may further include a spacer  104  in conjunction with the axle  102  in order to tailor the height of the axle  102  away from the pedal crank arm  106 . The thickness of the spacer  104  will, in general, depend on the particular preferences of the rider.  
         [0022]    Also illustrated in FIG. 1 is the binding assembly  101  comprised of a releasable coupling means and a pedal. In the preferred embodiment, the releasable coupling means is a clasp or receptacle in the shape of an arcuate cup comprised of the first structure  115 , second structure  117 , and third structure  118 . The first, second, and third structures are designed with the precision and tolerance necessary to receive the bearing  103  and limit the relative movement of the binding assembly  101  and bearing  103  in non-vertical directions. In particular, the width between the first structure  115  and the second structure  117  must be substantially equal to the depth of the outer surface  113  of the bearing  103  in order avoid a loose fit that may reduce the ability of the binding assembly  101  to remain operatively engaged to the bearing  103  when upward force is applied to the binding assembly  101 .  
         [0023]    The clasp should also be constructed of a substantially rigid material such as steel, titanium, aluminum, chromoly, or carbon fiber, for example, sufficient to withstand the static and dynamic forces exerted by a cyclist under stringent riding conditions. The clasp may further include portals  122 A,  122 B for allowing the egress of dirt from the interior side of the clasp and to permit visual alignment of the binding assembly  101  with the axle assembly  124 .  
         [0024]    The binding assembly  101  further includes a pedal  120  for engaging the cycling shoe  140  and transferring the forces exerted by the cyclist to the axle  102 . In the preferred embodiment, the pedal  120  is comprised of a substantially flat plate rigidly affixed to the releasable coupling means, although the plate may assume alternative shapes necessary for adaptation to various cycling shoes. In some embodiments, the pedal  120  further includes shoe fastening means  121  for securing the cycling shoe  140  to the binding assembly  101 , as discussed below in more detail.  
         [0025]    In some embodiments, the shoe fastening means may include a receptacle adapted to receive alternate forms of detachable pedal systems including the numerous clipless pedals on the market today.  
         [0026]    The thickness of the pedal  120  will depend on the material selected but, in general, should be a thin as reasonably possible in order to increase the ground clearance with the bottom of the pedal  120 , important during high speed angled turning or maneuvering. The pedal  120  should be constructed of a substantially rigid material such as steel, titanium, aluminum, chromoly, or carbon fiber, for example, sufficient to withstand the static and dynamic forces exerted by a cyclist under stringent riding conditions.  
         [0027]    An important feature of some embodiments of the present invention is the force-responsive locking means that firmly retains the binding assembly  101  engaged with the axle  102  until a predetermined force is exceeded. Once the predetermined force is exceeded, for example, where the cyclist dismounts the bicycle or is in an accident, the binding assembly  101  detaches or otherwise breaks-away from the axle  102 . The locking means is preferably designed to allow detachment the binding assembly  101  in a non-destructive manner, thus allowing the binding assembly  101  to later re-engage the axle  102 .  
         [0028]    Still referring to FIGS. 1 and 2, the force-responsive locking means in the preferred embodiment is comprised of a detent device with a spring-load ball bearing  127  in the axle  102  that engages a corresponding recess  116 B in the binding assembly  101 . The ball bearing  127  is held in position by the retaining washer  131  on one side and the set screw  126 , spring  128 , and plate  129  on the other.  
         [0029]    To engage the binding assembly  101  and axle assembly  124  in this embodiment, the cyclist lowers the binding assembly  101  on to the axle assembly  124  with the clasp vertically aligned with the bearing  103 . As the binding assembly  101  is lowered onto the axle  102 , the ball bearing  127  is guided by the race  116 A until the clasp fully engages the bearing  103 , at which point the ball bearing  127  seats into the recess  116 B. After being seated into the recess  116 B, the ball bearing  127 , under the force of the spring  128 , prevents the binding assembly  101  from being lifted off of the axle  102  during normal operating conditions. The force exerted by the spring may be adjusted as desired up to several hundred pounds using the set screw  126  that threadedly engages the axle within the recess  125 .  
         [0030]    In this preferred embodiment, the binding assembly  101  is permitted to disengage the axle by means of a linear force applied in the vertical direction, the direction normal to the pedal surface  119 . One skilled in the art will recognize that alternative embodiments of the present invention may be adapted to permit detachment of a binding assembly if a linear or rotational force is applied in one or more different directions. The present invention would be equally applicable to an apparatus in which the cyclist disengaged his foot by applying a twisting force about the pedal or a linear force outward in the direction of the axle axis, for example.  
         [0031]    Referring to FIG. 3, an interior side view of the binding assembly of the preferred embodiment is illustrated. The shape of the arcuate cup of the releasable coupling means is clearly visible, including the radial contour of the second structure  117  and third structure  118 . Located at the center of these concentric surfaces is the recess  116 B corresponding to the ball bearing  127  located on the axis  130  of the axle  102 . Leading to the recess  116 B is the race  116 A which approximately defines the direction that the binding assembly  101  is directed to engage and lock the axle assembly  124 .  
         [0032]    Also illustrated in the preferred embodiment is the guide  115 A which assists the axle  102  into the arcuate cup. The guide  115 A is elevated above the surface  115  by a distance represented by the depth of the surface  115 B, which is substantially equal to the thickness of the retainer  111 .  
         [0033]    Referring to FIG. 4, a view of the underside of the binding assembly and axle assembly when mounted into the pedal crank arm according to the preferred embodiment is illustrated. In the preferred embodiment, the pedal  120  has a width and length roughly corresponding to the ball of the cyclist&#39;s foot through which the energy is transferred during riding.  
         [0034]    In some embodiments, the pedal  120  includes shoe fastening means for securing the cycling shoe to the binding assembly  101 . The shoe fastening means may comprise holes or slots  121  sized and positioned to receive screws or bolts capable of rigidly securing a cycling shoe to the binding assembly during cycling. Of course, the screws, bolts or equivalent means may be detached, thereby allowing the shoe or binding assembly to be replaced. The pedal  120  may further comprise float means permitting the cycling shoe to “float,” i.e., move in an angular and lateral direction relative to the pedal  120  to increase comfort and efficiency for the rider. The float means may be achieved in some embodiments a hinge, bearing, pivot, articulated joint, or equivalent means.  
         [0035]    One skilled in the art will recognize the pedal  120  of the present invention also allows the cyclist to walk with the binding assembly  101  attached to the cycling shoe with minimal discomfort or damage to the binding assembly  101 . Unlike the prior art pedal assemblies, the cleat is not located underneath the rider&#39;s shoe where it would otherwise be subjected to the wear and tear that occurs when the rider walks on the cleats when dismounted from the bicycle. In some embodiments, the underside of the pedal  120  may further include a durable sole made or rubber or equivalent material for reducing wear of the pedal  120  and protectively concealing the screws or bolts that engage the cycling shoe.  
         [0036]    [0036]FIG. 5 is a front side view of binding assembly, axle, and crank arm of the preferred embodiment in the locked position. As shown, the clasp receives a portion of the axle assembly  124 , in the preferred embodiment, thereby engaging the axle assembly  124  in a manner than supports the transfer of force from. the cyclist&#39;s foot to the crank arm  106 .  
         [0037]    One skilled in the art will recognize that the advantage of interposing the detachable interface formed by the clasp and the axle assembly  124  between the rider&#39;s foot and the crank arm  106 , the height of the pedal surface  119  relative to the axle axis  13 O may be adjusted to improve the performance, efficiency, and performance of the cyclist. In particular, the offset position of the pedal surface  119  in the preferred embodiment is such that the axle axis  130  approximately coincides with the ball of the rider&#39;s foot. This configuration may be optimized according to biokinetics in a manner that was previously unavailable in prior art detachable pedal systems because of the thickness of the cleat system that occupied space below the pedal.  
         [0038]    Although the above description contains many specifics, these should not be construed as limiting the scope of the invention, but rather as merely providing illustrations of some of the presently preferred embodiments of this invention.  
         [0039]    Therefore, the invention has been disclosed by way of example and not limitation, and reference should be made to the following claims to determine the scope of the present invention.