Abstract:
A roller shoe has a pliable bottom. Rear wheels are independently rotatable about a rear axle recessed in the heel portion. A front wheel is rotatable on a front axle recessed in the arch portion. Both axles are removably yet firmly supported partially recessed within wheel housings. Rolling with front and rear wheels on a flat skating surface holds the forward portion of the shoe bottom clear of the skating surface. Tilting forward onto the front wheel alone allows pivoting while rolling. Tilting farther forward brings the forward portion down to sliding, standing or walking contact with the skating surface. Tilting backward onto the rear wheels alone allows pivoting while rolling. Tilting backward in the extreme brings the shoe heel into sliding or resting contact with the skating surface. Wheels are formed of urethane, axles and bearings of steel, shoe of textile or leather, shoe bottom of resinous or rubber material, and wheel housings of strong plastic such as nylon.

Description:
[0001]    This application claims the benefit of prior copending U.S. application Ser. No. 60/353,102, filed Jan. 30, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to active and recreational footwear and more particularly to wheeled shoe bottoms, especially to wheels housed partially recessed within a shoe bottom.  
           [0004]    2. Description of the Related Art  
           [0005]    A roller skate or roller blade typically has wheels mounted on a rigid structure extending downward from a shoe bottom as exemplified by U.S. Pat. No. 4,295,655, a roller skating shoe.  
           [0006]    A sport shoe typically has a pliable, cushioned sole as exemplified by U.S. Pat. No. 4,245,406, an athletic shoe.  
           [0007]    A sport shoe adapted to include a roller or wheel is exemplified by U.S. Pat. No. 6,120,039. Attempts have been made to adapt a roller shoe to be used as a walking shoe as exemplified by U.S. Pat. No. 5,785,327. Another rolling shoe is described by U.S. patent application Ser. No. 2001/001,9195 and U.S. Pat. No. 2001/005,4802 (the &#39; 9195  and &#39; 4802  applications, respectively). A retractable wheel mechanism can be bulky. Retractable wheels can make a shoe clumsy and heavy. The more frequently the wheels are removed, the greater the chance they will be mislaid and lost.  
           [0008]    In the &#39; 9195  and &#39; 4802  applications, a single wheel, or tandem wheels functioning as a single wheel, are placed within in the heel portion of the shoe bottom extending partially downward from the sole. A user (“skater”) can shift weight to his or her heel and lifting his or her toe and thus be able to roll. When weight is placed on the forward portion of the shoe, the flat surface of the sole of the shoe comes into contact with the walking surface. Rolling stops and the skater can stand or walk. This single-axle design with wheels in the heel portion has a single balance point, creating a teeter-totter effect whereby the skater&#39;s balance must constantly be adjusted. If the skater leans too far forward or rearward, he or she may fall. If a more easily balanced, more versatile, more stable roller-equipped shoe were available, skaters might find less fatigue and frustration and more enjoyment.  
         SUMMARY OF THE INVENTION  
         [0009]    It is a general object of the present invention to provide a versatile, enjoyable, stable, comfortable, easy-to-use, easy-to-learn roller shoe.  
           [0010]    In accordance with these objects and with others which will be described and which will become apparent, an exemplary embodiment of a roller shoe in accordance with the present invention comprises a shoe upper and a shoe bottom attached thereto. Rear left and right wheels and a front wheel are removably yet securely held partially recessed in wheel housings in the bottom surface of the shoe bottom. The rear left and right wheels contact a skating surface (i.e., any reasonably firm, reasonably flat ground surface such as a driveway, sidewalk, or rink) beneath the heel portion of the shoe bottom. The front wheel contacts the skating surface beneath the arch portion of the shoe bottom. The three points of contact with the skating surface define a plane. In an exemplary embodiment of a roller shoe in accordance with the present invention, that plane passes entirely beneath the shoe bottom and does not intersect the shoe bottom.  
           [0011]    When all three wheels are weighted, the skater can roll and can also enjoy the benefits of longitudinally separate wheel locations. These benefits include reduced fatigue in keeping the forward portion of the shoe bottom clear of the skating surface and reduced sensitivity to bumps.  
           [0012]    When only the front wheel is weighted, the skater can roll on the front wheel, tilt forward until the forward portion of the shoe bottom touches the skating surface (causing friction), or pivot with very little torque, all with subtle, barely observable changes in the angle of the shoe bottom relative to the skating surface. The skater enjoys the benefits of a roller shoe whose forward portion is substantially available for stopping the rolling motion and for standing and walking.  
           [0013]    When only the rear wheels are weighted, the skater can roll or can pivot with very little torque, enjoying the benefit of left and right rear wheels mounted on independent bearings.  
           [0014]    In a preferred embodiment, the front wheel is of smaller diameter than the diameter of the rear wheels and the front axle is placed at about the same height as the rear axle. The front wheel can be placed forward of the rear wheels and beneath the arch portion. Having less height, the front wheel requires less vertical clearance, permitting the shoe bottom to be thinner in the arch than in the heel. This can make the shoe more comfortable and can also urge the user into a slightly forward position, depending on the angle of the insole of the shoe.  
           [0015]    The wheels themselves are attached to the sole of the shoe and are partially recessed within the sole. The wheels are positioned on the sole such that roughly 65% of the surface of the sole forms a walking surface. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    For a further understanding of the objects and advantages of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawing, in which like parts are given like reference numbers and wherein:  
         [0017]    [0017]FIG. 1 is a bottom perspective view of the roller shoe in accordance with the present invention;  
         [0018]    [0018]FIG. 2 is a bottom plan view thereof;  
         [0019]    [0019]FIG. 3 is a bottom plan view of the shoe bottom and wheel assemblies thereof;  
         [0020]    [0020]FIG. 4 is a rear elevational view thereof;  
         [0021]    [0021]FIG. 5 is a rear elevational view thereof;  
         [0022]    [0022]FIG. 6 is a side elevational view thereof;  
         [0023]    [0023]FIG. 7 is a side elevational view thereof;  
         [0024]    [0024]FIG. 8 is bottom sectional view thereof;  
         [0025]    [0025]FIG. 9 is a bottom perspective view thereof;  
         [0026]    [0026]FIG. 10 is partial rear sectional view thereof;  
         [0027]    [0027]FIG. 11 is partial side sectional view thereof;  
         [0028]    [0028]FIG. 12 is a partial side cut-away view thereof;  
         [0029]    [0029]FIG. 13 is partial side cut-away view thereof;  
         [0030]    [0030]FIG. 14 is a partial side cut-away view thereof;  
         [0031]    [0031]FIG. 15 is a partial rear cut-away view thereof;  
         [0032]    [0032]FIG. 16 is partial rear cut-away view thereof;  
         [0033]    [0033]FIG. 17 is partial rear cut-away view thereof;  
         [0034]    [0034]FIG. 18 is a partial perspective view thereof;  
         [0035]    [0035]FIG. 19 is a partial perspective view thereof; and  
         [0036]    [0036]FIG. 20 is a partial bottom sectional view thereof. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]    The invention will now be described with reference to FIG. 1, which illustrates in bottom perspective view a preferred embodiment of the roller shoe  40  in accordance with the present invention shown generally by the reference number  40  comprising a shoe upper  52  and a shoe bottom  54 . The shoe bottom  54  forms a left side  60 , a right side  62 , a top surface  56 , a bottom surface  58 , a front end  64 , a rear end  66 , a heel portion  68 , an arch portion  70 , and a forward portion  72 . The forward portion  72  of the shoe bottom  54  forms a front stopping surface  74 . The heel portion  68  forms a rear stopping surface  76 . The arch portion  70  of the shoe bottom  54  forms a front wheel housing  78  in which is disposed a front wheel assembly  82  comprising a front wheel  86  having a front wheel periphery  92 . The heel portion  68  of the shoe bottom  54  forms a rear wheel housing  80  in which is disposed a rear wheel assembly  84  comprising a rear left wheel  88  having a rear left wheel periphery  94  and a rear right wheel  90  having a rear right wheel periphery  96 .  
         [0038]    With continued reference to FIG. 1, the shoe upper  52  comprises laces  53  which are adapted to fastening the shoe upper  52  to a person&#39;s foot. The shoe upper  52  is formed of leather, textiles, thermoplastic and thermosetting resins, rubber, or subcombinations of these and other materials common in the manufacture of footwear. Stitching, welding, adhesives, Velcro® brand adherent strips, and various interference-fitting fasteners may be used to assemble the shoe upper  52  in ways well known to shoemakers. In similar manner, the shoe upper  52  is joined to the top surface  56  of the shoe bottom  54  to form the roller shoe  40 .  
         [0039]    With continued reference to FIG. 1, the shoe bottom  54  is made of materials comparable to those of the shoe upper  52 , although tending to incorporate fewer textiles and more rubber and other resinous materials. The shoe bottom  54  is generally thick enough and elastic enough to serve as a cushioned shoe for standing, walking, running and jumping. The shoe bottom  54  in this embodiment of the present invention is approximately two inches thick at the heel and approximately ¾ inch thick at the toe. The bottom surface  58  of the shoe bottom  54  generally is formed of a water-impervious, wear-resistant material suitable for outdoor as well as indoor use. The bottom surface  58  may form treads or other functional features. The bottom surface  58  may form ornamental features.  
         [0040]    With continued reference to FIG. 1, the forward portion  72  of the shoe bottom  54 —generally, that large flat or gently curved portion of the shoe bottom  54  that is between the arch portion  70  of the shoe bottom  54  and the front end  64  of the shoe bottom  54 —may be stood upon or walked upon by a person is placing weight on the ball or toes of the foot. The front wheel  86 , rear left wheel  88 , and rear right wheel  90  are oriented to permit forward and rearward rolling motion on a relatively smooth walking surface (or skating surface) and are located so as to support the heel portion  68  and the arch portion  70  of the shoe bottom  54  a short distance above such a walking surface. It will be appreciated that a person wearing the roller shoe  40  may allow weight to be borne by the rear wheel assembly  84  either alone or in combination with the front wheel assembly  82 . It will also be appreciated that the person may use the rear left wheel  88  and rear right wheel  90  as a fulcrum and rotate the front end  64  of the roller shoe  40  upward until the rear stopping surface  76  of the heel portion  68  touches the walking surface. This maneuver may slow or stop any rolling motion of the roller shoe  40 . Alternatively, the person may shift enough weight to the forward portion  72  of the shoe bottom  54  that the forward stopping surface touches the walking surface. This maneuver, too, may slow or stop any rolling motion of the roller shoe  40 , and may under some circumstances result in a convenient and graceful transition from rolling motion to walking motion.  
         [0041]    [0041]FIG. 2 shows a bottom plan view of an embodiment of the roller shoe  40  in accordance with the present invention shown generally by the reference number  40 , comprising the left side  60 , the right side  62 , the bottom surface  58 , the front end  64 , the rear end  66 , the heel portion  68 , the arch portion  70 , the forward portion  72 , the front stopping surface  74 , the rear stopping surface  76 , the front wheel housing  78 , the front wheel assembly  82 , the front wheel  86  and front wheel periphery  92 , the rear wheel housing  80 , the rear wheel assembly  84 , the rear left wheel  88  and rear left wheel periphery  94 , and the rear right wheel  90  and rear right wheel periphery  96 . The front wheel assembly  82  comprises a front axle  98  which defines a front wheel axis of rotation indicated by arrow Y1. The rear wheel assembly  84  comprises a rear axle  100  which defines a rear wheel axis of rotation indicated by arrow Y2.  
         [0042]    [0042]FIG. 3 shows a bottom plan view as in FIG. 2 above after the front wheel assembly  82  and the rear wheel assembly  84  have been removed and placed proximate the right side  62  of the shoe bottom  54  (the left shoe of a pair being shown). The front wheel  86  is mounted on a front axle  98  having axially extending front left axle end  102  and front right axle end  104 . The rear left wheel  88  and the rear right wheel  90  are both mounted on a rear axle  100  having axially extending rear left axle end  106  and rear right axle end  108 . The front wheel  86  has a diameter smaller than the diameter of the rear left wheel  88  and of the rear right wheel  90 . As will be discussed in greater detail with reference to this and other drawing Figures, the front wheel housing  78  is formed in the arch portion  70  of the shoe bottom  54 . The rear wheel housing  80  is formed in the heel portion  68  of the shoe bottom  54 . The front wheel housing  78  comprises a front left axle support  122  formed to receive the front left axle end  102  and front right axle support  132  formed to receive the front right axle end  104 . The rear wheel housing  80  forms a rear left axle support  142  formed to receive a rear left axle end  106  and a rear right axle support  152  formed to receive rear right axle end  108 .  
         [0043]    [0043]FIG. 4 shows a rear elevational view of the roller shoe  40  in accordance with the present invention shown generally by the reference number  40 , comprising the left side  60 , the right side  62 , the bottom surface  58 , the rear end  66 , the top surface  56  of the shoe bottom  54  as seen at the rear end  66  of the shoe bottom  54 , the heel portion  68 , the rear stopping surface  76 , the front wheel  86  and front wheel periphery  92 , the rear left wheel  88  and rear left wheel periphery  94 , and the rear right wheel  90  and rear right wheel periphery  96 .  
         [0044]    [0044]FIG. 5 shows a rear elevational view of the roller shoe  40  in accordance with the present invention shown generally by the reference number  40 , comprising the left side  60 , the right side  62 , the bottom surface  58 , the rear end  66  of the shoe bottom  54 , the top surface  56  of the shoe bottom  54  as seen at the rear end  66  of the shoe bottom  54 , the heel portion  68 , the front wheel  86  and front wheel periphery  92 , the rear left wheel  88  and rear left wheel periphery  94 , and the rear right wheel  90  and rear right wheel periphery  96 . The rear wheel housing  80  is shown located within the shoe bottom  54  approximately midway between the left side  60  and the right side  62  of the shoe bottom  54 . The rear wheel housing  80  comprises a horizontally extending rear crossmember  166 . The rear wheel housing  80  comprises a downward-projecting rear left support column  116  and a downward-projecting rear right support column  114 , which, respectively, form the rear left axle end  106  support and the rear right axle end  108  support. Similarly, the front wheel housing  78  is shown located within the shoe bottom  54  approximately midway between the left side  60  and the right side  62  of the shoe bottom  54 . The front wheel housing  78  comprises a horizontally extending front crossmember  164 . The front wheel housing  78  comprises a downward-projecting front left support column  112  and a downward-projecting front right support column  110 , which, respectively, form the front left axle support  122  and the front right axle support  132 .  
         [0045]    With continued reference to FIG. 5, the rear axle  100  extends between the rear left axle support  142  and the rear right axle support  152 . The rear left wheel  88  and the rear right wheel  90  are located midway on the rear axle  100 , side-by-side, slightly separated. The front wheel  86  is located midway on the front axle  98 . As shown in broken lines in this figure, the front axle  98  and the rear axle  100  are approximately superimposed, as are the front wheel housing  78  and the rear wheel housing  80 , and the front wheel  86  and the rear left wheel  88  and the rear right wheel  90 . The front axle  98  defines a front wheel axis of rotation indicated by arrow Y1. The rear axle  100  defines a rear wheel axis of rotation indicated by arrow Y2. Y1 and Y2 are approximately superimposed on one another in this view.  
         [0046]    With continued reference to FIG. 5, three broken lines show the approximate height of the top surface  56  of the shoe bottom  54  at L1 above the rear wheel housing  80 , at L2 above the front wheel housing  78 , and at L3 above the forward portion  72 . As shown, in this embodiment, the front crossmember  164  is not located as far upward within the shoe bottom  54  as does the rear wheel housing  80 . Also as shown, in this embodiment, the front wheel  86  has a diameter smaller than that of the rear left wheel  88  and the rear right wheel  90 . It will be appreciated that this arrangement allows the front wheel periphery  92  to extend a shorter distance downward beneath the bottom surface  58  than do the rear left wheel periphery  94  and the rear right wheel periphery  96 , while, at the same time, the front wheel periphery  92  extends a shorter distance upward above the shoe bottom  54  periphery. This shorter upward extent of the front wheel periphery  92  allows the front wheel housing  78  to require less vertical clearance within the shoe bottom  54  than does the rear wheel housing  80 . As a result, the top surface  56  of the shoe bottom  54  may describe a natural arch contour, declining as it extends forward from the rear end  66 , through L1, L2, and L3, to form a comfortable roller shoe  40  having a mildly elevated heel portion  68  and a supportive arch portion  70 , even while providing for a front wheel periphery  92  extending a shorter distance downward from the bottom surface  58  of the shoe bottom  54  than the rear left wheel periphery  94  and the rear right wheel periphery  96  extend. Thus, the preferred embodiment of the roller shoe  40  in accordance with the present invention can be positioned on all three wheels, roughly level or toe slightly lowered relative to the skating surface, and with the forward portion  72  held slightly above the skating surface. It should be noted that the apparent uppermost portion of the shoe bottom  54 , or “top surface  56  of the shoe bottom  54 ,” as viewed on the outside of the rear end of the shoe referred to above, might not coincide with level L1 on the inside. This might happen, for example, where an outer portion of a shoe bottom wraps upward upon a portion of an outer surface of a shoe upper.  
         [0047]    [0047]FIG. 6 shows a side view of the right side of the heel portion  68  and the arch portion  70  of the shoe bottom  54  in the preferred embodiment of the roller shoe  40  in accordance with the present invention, comprising the top surface  56 , the bottom surface  58 , the rear end  66 , the rear stopping surface  76 , the front wheel  86  and front wheel periphery  92 , and the rear right wheel  90  and rear right wheel periphery  96 . The rear left wheel  88  and rear left wheel periphery  94  are not shown, being obscured by the rear right wheel  90 .  
         [0048]    [0048]FIG. 7 shows a side elevational view of the right side of the roller shoe  40  in accordance with a preferred embodiment of the present invention including the heel portion  68  and the arch portion  70  of the shoe bottom  54 , the top surface  56 , the bottom surface  58 , the rear end  66 , and the rear stopping surface  76 . The front wheel housing  78  comprises the front crossmember  164  and the downward-projecting front right support column  110  (the front left support column  112 , not shown, being superimposed thereon). Similarly, the rear crossmember  166  comprises the downward-projecting rear right support column  114  (the rear left support column  116 , not shown, being superimposed thereon). The front right support column  110  forms the front right axle support  132 , which will be described in greater detail as a leftward-facing, downward opening slot formed in the front right support column  110 . In similar fashion, the rear right support column  114  forms the rear right axle support  156 . The front left axle support  122  (not shown) and the rear left axle support  142  (not shown) are formed and located as mirror images of their right-handed counterparts.  
         [0049]    With continued reference to FIG. 7, the front wheel assembly  82  is removably mounted within the front wheel housing  78  as follows: the front right axle support  132  receives the front right axle end  104 , which is shown disposed therein, which is insertable therein from below, and which is interference-fitted firmly therein, such that a person must pull downward with approximately five to fifteen pounds force or push strongly from one side while pulling strongly downward in order to dislodge the front right axle end  104  and the front left axle end  102  from the front wheel housing  78 . In similar manner, the rear wheel assembly  84  is mounted within the rear wheel housing  80 .  
         [0050]    With continued reference to FIG. 7, the front crossmember underside  118  is spaced apart from the front wheel periphery  92  and the rear crossmember underside  120  is spaced apart from the rear right wheel periphery  96  and the rear left wheel periphery  94  (not shown). The rear left support column  116  (not shown) is taller than the front left support column  112  (not shown). The rear right support column  114  is taller than the front right support column  110 . As a result, the rear crossmember  166  is higher above the bottom surface  58  of the shoe bottom  54  than is the front crossmember  164 , while the rear right axle end  108 , the rear left axle end  106  (not shown), the front right axle end  104 , the front left axle end  102  (not shown), and the axle supports that receive them, are all located at approximately the same height above the bottom surface  58  of the shoe bottom  54 . The top surface  56  of the shoe bottom  54  is located above and relatively near to the front crossmember  164  and the rear crossmember  166 .  
         [0051]    With continued reference to FIG. 7, A-A defines a plane coinciding with the bottom surface  58  of the shoe bottom  54  in the heel portion  68  and the arch portion  70  thereof. The forward portion  72  of the shoe bottom  54  extends forward while curving gently upward above plane A-A. Z defines the vertical axis as being normal to plane A-A. B-B defines a tangent of the front wheel periphery  92  and either the rear right wheel periphery  96  or the rear left wheel periphery  94 . B-B passes beneath the shoe bottom  54  and does not intersect the shoe bottom  54 . C-C defines a tangent of the front wheel periphery  92  and the forward portion  72  of the upwardly-curving shoe bottom  54 . D-D defines a tangent of the rear right wheel periphery  96  or the rear left wheel periphery  94 . D-D passes beneath the shoe bottom  54  and does not intersect the shoe bottom  54 . E-E defines a tangent of the rear end  66  of the shoe bottom  54  and the rear right wheel periphery  96  or the rear left wheel periphery  94 .  
         [0052]    A person using the roller shoe  40  in accordance with the present invention (we shall call this person “the skater”) can wear it with the front wheel assembly  82 , the rear wheel assembly  84 , both of them, or neither of them, installed.  
         [0053]    With neither of the wheel assemblies installed, the skater can walk normally.  
         [0054]    Installing only the rear wheel assembly  84  in each roller shoe  40  (both the left and right shoe), the skater can roll, walk, or do both. On a reasonably hard, reasonably flat skating surface (a sidewalk, floor, ramp, driveway, or the like), when the skater lifts the toe portion of a roller shoe  40  away from the skating surface, the weight placed on that shoe is transmitted by the rear axle  100  (coinciding with the rear wheel axis of rotation) to the rear left wheel  88  and the rear right wheel  90 . Oriented as they are in the shoe bottom  54  for forward and backward rolling motion, the rear left wheel  88  and the rear right wheel  90  will tend to allow the roller shoe  40  to continue to roll, forward or backward as the case may be, until some force alters this rolling motion. Such a force can result from gravity on a hill, from rolling friction, from the skater pushing or stopping with the other foot, or from contact of the roller shoe  40  with the skating surface.  
         [0055]    The roller shoe  40  can contact the skating surface in at least two ways. With only the rear wheel assembly  84  installed, if the roller shoe  40  is rotated sufficiently forward (toe down) about the rear wheel axis of rotation, the bottom surface  58  of the forward portion  72  of the shoe bottom  54  will touch the skating surface. The resulting sliding friction will slow or stop the rolling motion of the roller shoe  40 . The part of the bottom surface  58  of the forward portion  72  that tends most often to touch the skating surface is referred to as the front stopping surface  74 . If the shoe is rotated sufficiently rearward (toe up) about the rear wheel axis of rotation, the bottom surface  58  of the heel portion  68  of the shoe bottom  54 , proximate the rear end  66  of the shoe bottom  54 , will touch the skating surface. The resulting sliding friction will slow or stop the rolling motion of the roller shoe  40 . The part of the bottom surface  58  of the heel portion  68  that tends most often to touch the skating surface is referred to as the rear stopping surface  76 .  
         [0056]    With only the rear wheel assembly  84  installed in each roller shoe  40 , the skater can roll continuously by holding both roller shoes at intermediate orientations such that neither the front stopping surfaces nor the rear stopping surfaces touch the skating surface. If the skater becomes unbalanced, he or she must reposition one or both roller shoes beneath his or her center of mass in order not to fall. In order to stabilize his or her center of mass relative to the support he or she receives from the two roller shoes, the skater may prefer to position one foot forward (“front foot”) and one foot rearward (“back foot”).  
         [0057]    In this front foot and back foot position, if a forward-rolling skater&#39;s center of mass gets too far behind both roller shoes, he or she may raise the toe of the front foot or the rear foot or both, thereby engaging one or both rear stopping surfaces, retarding the forward motion of one or both roller shoes until his or her center of mass is more stably supported.  
         [0058]    In this front foot and back foot position, if a forward-rolling skater&#39;s center of mass gets too far ahead of both roller shoes, he or she may, through a deliberate change of posture and leg position, move one roller shoe  40  to a new front foot position. Otherwise, the skater will tilt forward until, eventually, at least one roller shoe  40  has rotated forward sufficiently that its front stopping surface  74  touches the skating surface. Friction will then retard the forward motion of that roller shoe  40 . A likely result will be that the skater&#39;s center of mass will be even less stably positioned, farther ahead of the support provided by the roller shoes, whereupon even greater physical effort will be required in order to return to stable rolling motion.  
         [0059]    Whether the skater&#39;s feet are positioned front and back or side by side, the skater must use muscular tension to stabilize both roller shoes at intermediate angles about the rear wheel axis of rotation such that neither front stopping surface  74  touches the skating surface. The farther forward the skater&#39;s center of mass relative to the support provided by the roller shoes, the more powerfully the skater will have to contract the muscles that raise his or her foot toward a toes-up position. The skater&#39;s reliance on muscular tension alone to stabilize both roller shoes at such intermediate angles has two consequences. First, the skater must develop sufficient muscular power to stabilize the roller shoes at the intermediate angles. Second, the skater must develop the skill and coordination to do so. Both the muscular power and the skill and coordination are developed over time. A novice skater who becomes frustrated and quits early might miss out on the enjoyment of the roller shoes.  
         [0060]    Using the preferred embodiment of the roller shoe  40  in accordance with the present invention, the skater can install both the rear wheel assembly  84  and the front wheel assembly  82 . With both wheel assemblies installed, if the skater becomes unbalanced in the forward direction, such that his or her center of mass has moved ahead of the support provided by the roller shoes, the front wheel assembly  82  provides the skater an additional means of stabilizing one or both roller shoes at intermediate angles about the rear wheel axis of rotation such that neither of the front stopping surfaces touches the skating surface.  
         [0061]    With reference to the side view of FIG. 7, it will be noted that the skater may, as set forth above, use muscular tension to stabilize the roller shoe  40  at an intermediate angle such that the front stopping surface  74  does not touch the skating surface. However, as the skater rotates the roller shoe  40  forward about the rear wheel axis of rotation within the aforementioned range of intermediate angles, an angle is attained at which the front wheel periphery  92  touches the skating surface. As the skater progressively transfers weight from rear left wheel periphery  94  and the rear right wheel periphery  96  onto the front wheel periphery  92 , a new, more forward, point of support is established beneath the arch portion  70  of the shoe bottom  54 .  
         [0062]    With continued reference to FIG. 7, the consequences are several. The support provided by the roller shoe  40  is moved forward relative to the skater&#39;s center of mass, aiding the skater in regaining or maintaining a position of stable balance while rolling. Additionally, because the front wheel  86  is located forward of the rear left wheel  88  and the rear right wheel  90 , the support provided at the front wheel axis of rotation tends greatly to lessen the amount of muscular tension needed to stabilize the roller shoe  40  at an intermediate angle such that the forward stopping surface does not touch the skating surface. Moreover, if the skating surface has any irregularities, they are less likely to perturb the angle of the roller shoe  40  or the balance of the skater. Any one irregularity in the skating surface is unlikely to be encountered by all wheels at the same time, because the front wheel periphery  92  will likely encounter it before the rear wheels do. Two successive smaller shocks are less disturbing than one larger one.  
         [0063]    Contrastingly, if the front wheel assembly  82  were removed, a bump in the skating surface during forward rolling motion might cause the roller shoe  40  to rotate forward about the rear wheel axis of rotation to an angle at which the front stopping surface  74  touches the skating surface. Even if this angle is maintained only momentarily, the resulting friction tends to force the skater&#39;s foot rearward relative to his or her knee and hip. As a result, the roller shoe  40  will tend to rotate farther forward, increasing the magnitude, duration and frequency of disturbances resulting from such a bump.  
         [0064]    However, with the front wheel assembly  82  installed, the same bump will first cause a transfer of weight onto the front wheel  86 . Only after that, would the bump, if severe enough, cause the roller shoe  40  to rotate forward, about the front wheel axis of rotation, to an angle such that the front stopping surface  74  touches the skating surface. Thus, the preferred embodiment of the roller shoe  40  in accordance with the present invention limits or relieves muscular fatigue and frustration.  
         [0065]    With the rear wheel assembly  84  and the front wheel assembly  82  installed, the preferred embodiment of the roller shoe  40  in accordance with the present invention enhances the skater&#39;s ability to pivot. It will be noted that the skater can hold the roller shoe  40  at an angle such that only the left rear wheel periphery and the right rear wheel periphery touch the skating surface. Because separate sets of bearings  168  independently affix the left rear wheel and the right rear wheel to the rear axle  100 , the left rear wheel and the right rear wheel are free to rotate in opposite directions. Consequently, the skater may pivot easily and smoothly while holding the roller shoe  40  at such an angle.  
         [0066]    With the rear wheel assembly  84  and the front wheel assembly  82  installed, it will also be noted that the skater can transfer weight from the rear axle  100  to the front axle  98  until the roller shoe  40  begins to rotate forward about the front wheel axis of rotation. As can be seen in FIG. 7, there is a range of angles at which neither the rear left wheel periphery  94 , nor the rear right wheel periphery  96 , nor the front stopping surface  74 , nor the rear stopping surface  76 , touches the skating surface. At such angles, the skater can pivot easily and smoothly. The skater may well prefer to do so, for these angles are the first ones encountered as the skater makes a transition from walking (or standing) to rolling.  
         [0067]    With the rear wheel assembly  84  and the front wheel assembly  82  installed, the preferred embodiment of the roller shoe  40  in accordance with the present invention enhances the skater&#39;s ability to make graceful transitions between rolling and walking. Those transitions occur when the front wheel  86  is carrying weight. The front wheel  86  is closer to the front stopping surface  74  than is the rear wheel. Consequently, a given change in the angle of the roller shoe  40  about the front wheel axis of rotation relative to the skating surface will produce a smaller change in the clearance between the front stopping surface  74  and the skating surface. It is thus easier for the skater to modulate the friction that results, and hence easier for the skater to make a smooth transition between rolling and walking. In some situations, the skater might place a high value on making a smooth transition between rolling and walking. For example, the skater might prefer not to draw attention to the fact that the shoes are roller shoes instead of ordinary shoes, and might therefore prefer to avoid making jerky movements. In some situations, the skater might prefer to make transitions between walking and rolling motion without stopping to uninstall or remove any of the wheel assemblies. Thus, it is advantageous that all of the wheels of the preferred embodiment of the roller shoe in accordance with the present invention are located such that the forward portion  72  of the shoe bottom  54  is available for walking or standing. Contrastingly, a roller skate, even if equipped with a toe brake, does not have a forward surface readily available for walking or standing.  
         [0068]    With reference again to FIG. 3, the front wheel housing  78  is formed in the arch portion  70  of the shoe bottom  54  and is shaped to hold the front crossmember  164  (not shown), the front left support column  112  (not shown), and the front right support column  110  (not shown) while providing clearance for the front wheel assembly  82  (not shown). Likewise, the rear wheel housing  80  is formed in the heel portion  68  of the shoe bottom  54  and is shaped to hold the rear crossmember  166  (not shown), the rear left support column  116  (not shown), and the rear right support column  114  (not shown) while providing clearance for the rear wheel assembly  84  (not shown). The material of the bottom surface  58  of the shoe bottom  54  may also form the surfaces of the front wheel housing  78  and the rear wheel housing  80 . The material of the shoe bottom  54  itself may be thickened, hardened, or reinforced as needed to strengthen the front wheel housing  78  and the rear wheel housing  80 .  
         [0069]    [0069]FIG. 8 shows a bottom sectional view of the heel portion  68  and the arch portion  70  of the shoe bottom  54  in the preferred embodiment of the roller shoe  40  in accordance with the present invention, comprising the front wheel housing  78 , the front crossmember  164 , the front right support column  110 , and the front left support column  112  (which may be regarded as a mirror image of the right). The front left support column  112  forms an inner surface which is inscribed to form a front prong  124 , a rear prong  126 , a lateral surface  128 , and an arch  130 , thus defining the front left axle support  122 . Similarly, the front right support column  110  forms an inner surface which is inscribed to form a front prong  134 , a rear prong  136 , a lateral surface  138 , and an arch  140 , thus defining the front right axle support  132 . In like manner, the rear left support column  116  forms an inner surface which is inscribed to form a front prong  144 , a rear prong  146 , a lateral surface  148 , and an arch  150 , thus defining the rear left axle support  142 ; and the rear right support column  114  forms an inner surface which is inscribed to form a front prong  154 , a rear prong  156 , a lateral surface  158 , and an arch  160 , thus defining the rear right axle support  152 .  
         [0070]    With continued reference to FIG. 8, the front crossmember  164 , front left support column  112 , and front right support column  110  fit snugly into the front wheel housing  78 . Similarly, the rear crossmember  166 , rear left support column  116 , and rear right support column  114  fit snugly into the rear wheel housing  80 .  
         [0071]    [0071]FIG. 9 shows a bottom perspective view of the heel portion  68  of the shoe bottom  54  in the preferred embodiment of the roller shoe  40  in accordance with the present invention, comprising the rear wheel housing  80 , the rear crossmember  166 , and the rear left support column  116 . The front prong  144 , the rear prong  146 , the lateral surface  148 , and the arch  150  form the rear left axle support  142 .  
         [0072]    [0072]FIG. 10 is a composite rear sectional view of the rear left support column  116 , the rear crossmember  166  (to the midpoint thereof, the front crossmember  164  (to the midpoint thereof), and the front right support column  110 , each section being taken at the highest extent of the arch  150  formed in the rear left support column  116  or of the arch  140  formed in the front right support column  110 . The rear left support column  116  forms the arch  150  and the lateral surface  148  of the rear left axle support  142 . Similarly, the front right support column  110  forms the arch  140  and the lateral surface  138  of the front right axle support  132 . The rear left support column  116  (and its right counterpart, not shown) is taller than the front right support column  110  (and its left counterpart, not shown). The rear left support column  116  is formed integrally with the rear crossmember  166  and the rear right support column  114  (not shown). Similarly, the front right support column  110  is formed integrally with the front crossmember  164  and the front left support column  112  (not shown).  
         [0073]    [0073]FIG. 11 shows a side sectional view, as seen from the right, of the front left support column  112  with front prong  124 , rear prong  126 , lateral surface  128 , and arch  130 ; the front crossmember  164 , the rear left support column  116  with front prong  144 , rear prong  146 , lateral surface  148 , and arch  150 ; and a top surface member  162  of the shoe bottom  54  (not shown). As illustrated, the top surface member  162  is formed separately from the front crossmember  164  and the rear crossmember  166 . This being so, the front crossmember  164  and the rear crossmember  166  may be inserted into a shoe bottom  54  (not shown) that has previously been molded with the top surface member  162  in place. A weld, an adhesive, or an interference fit may be used to immobilize the front crossmember  164  within the front wheel housing  78  (not shown) and the rear crossmember  166  within the rear wheel housing  80  (not shown). Alternatively, the front crossmember  164  and the rear crossmember  166  may first be joined to the top surface member  162  or formed integrally with the top surface member  162 . The balance of the shoe bottom  54  (not shown) may then be formed around these structures or they may be inserted into the balance of the shoe bottom  54  (not shown) from above.  
         [0074]    With continued reference to FIG. 11, the front crossmember  164 , rear crossmember  166 , front left support column  112  (not shown), front right support column  110  (not shown), rear left support column  116  (not shown), and rear right support column  114  (not shown), and top surface member  162  of the preferred embodiment of the roller shoe  40  are formed by injection molding, casting, or other common methods from nylon, metal, or other suitably tough and durable material. In a preferred embodiment, the material for the wheel housing is injection grade plastic (NANYA 8018), the injection plastic housing is inserted from the top of the outsole, the outsole is made of compression molded rubber and the housing is sandwiched between the outsole and the upper of shoe.  
         [0075]    [0075]FIG. 18 shows a perspective view of a preferred embodiment of the roller shoe in accordance with the present invention including the shoe bottom  54  in which are formed the front wheel housing  78  and the rear wheel housing  80 . Shown located above the shoe bottom  54  is the top surface member  162  and, formed integrally therewith, the rear left support column  116 , the front left support column  112 , and the front right support column  110  which forms the front prong  124 , the rear prong  126  and the lateral surface  128 .  
         [0076]    [0076]FIG. 19 shows the view of FIG. 18 after the top surface member  162  has been lowered onto the shoe bottom  54  such that the support columns are in their final locations within the wheel housings in the shoe bottom.  
         [0077]    In a preferred embodiment, the material for the wheel housing is injection grade plastic (NANYA  8018 ), a propylene copolymer chosen for strength and support. More particularly, the material used is polyamide  6  mixed with ethylene. The wheel housing is set from the inner side of the outsole with its edges hung and fit the outsole rubber blocks which we make more supportive by higher physical properties. The thick and hard insole material between upper and the outsole supports the housing from the pressure of riding. The outsole has very high density EVA filler to give the best cushion.  
         [0078]    In a preferred embodiment of a roller shoe in accordance with the present invention, the materials are as follows:  
         [0079]    Wheel  
         [0080]    polyester polyol (PTMEG): 53%  
         [0081]    diphenylmethane-4,4′-diisocyanate: 32%  
         [0082]    chain extender: 8%  
         [0083]    reaction regulant (DSE-535T): 3%  
         [0084]    silicone surfactant (DSE 200C): 2%  
         [0085]    antioxidant (DSE-71710): 1%  
         [0086]    amine catalyst: 1%  
         [0087]    Outsole (Rubber)  
         [0088]    TTR-5L (natural rubber): 18%  
         [0089]    1502 (synthetic rubber): 18%  
         [0090]    BR-01 (synthetic rubber): 30%  
         [0091]    ZEOSIL#155: 23%  
         [0092]    SI-69 (abrasion improvement): 3%  
         [0093]    M (acceleration): 3%  
         [0094]    DM (acceleration): 3%  
         [0095]    P-OIL: 2%  
         [0096]    Axle  
         [0097]    Steel 45C  
         [0098]    Injection  
         [0099]    polyamide 6: 92%  
         [0100]    ethylene propylene copolymer: 5.60%  
         [0101]    polyolefin resin: 1.26%  
         [0102]    dispersion agent (ethylene bis stearamide): 0.80%  
         [0103]    lubricant (AC 540): 0.14%  
         [0104]    stabilizer agent (1010): 0.20%  
         [0105]    Hub  
         [0106]    polycarbonate  
         [0107]    In a preferred embodiment, the plastic housing is inserted from the top of the outsole. The outsole is made of compression molded rubber. The housing is sandwiched between the outsole and the upper of shoe.  
         [0108]    In a preferred embodiment, the wheels are made from polyurethane and comprise a contained core made from polycarbonate. The bearings are ABEC-5 chrome bearings. The axle is formed of steel 45C. Snap rings are used to hold the bearings on the axle.  
         [0109]    [0109]FIG. 12 shows a side cut-away view of the roller shoe in accordance with the present invention including the front left support column  112 , the front crossmember  164 , the top surface member  162 , and the rear left support column  116 . The front left support column  112  forms the front prong  124 , the rear prong  126 , the arch  130 , and the lateral surface  128 . Similarly, the rear left support column  116  forms the front prong  144 , the rear prong  146 , the arch  150 , and the lateral surface  148 . The front left axle end  102  is shown located directly beneath the arch  130 . The rear left axle end  106  is shown located directly beneath the arch  150 .  
         [0110]    [0110]FIG. 13 shows the side cut-away view of FIG. 12 as the front left axle end  102 , when move upward toward the arch  130 , urges the front prong  124  c and the rear prong  126  apart from one another. Elastic deformation of the front prong  124 , the rear prong  126 , and the front left support column  112  that forms them is accompanied by pressure and friction which resists the vertical movement of the front left axle end  102  relative to the front left support column  112 .  
         [0111]    [0111]FIG. 14 shows the side cut-away view of FIGS. 12 and 13 after the front left axle end  102  has been thrust into contact with the arch  130 . So positioned, the front left axle end  102  is capable of bearing a generally downward force corresponding to the loads the roller shoe  40  exerts upon it during use. So positioned, the front left axle end  102  is immobilized relative to the front left support column  112  due to the aforementioned friction. Strong pulling, shoving, or prying is necessary to remove the front left axle end  102  from this position.  
         [0112]    With continued reference to FIG. 12, FIG. 13, and FIG. 14, the rear left axle end  106  fits proximate the arch  150 . In the same manner, the opposite axle ends, namely the front right axle end  104  and the rear right axle end  108 , fit and are immobilized proximate the arches  140  and  160  (not shown) of the front and rear right support columns  110  and  114  (also not shown).  
         [0113]    [0113]FIG. 15 shows a rear cut-away view of the roller shoe in accordance with the present invention including the rear crossmember  166 , the rear left support column  116  and arch  150 , the rear right support column  114  and arch  160 , the rear left axle end  106 , the rear right axle end  108 , and the rear left wheel  88  and rear right wheel  90 . The rear left axle end  106  and the rear right axle end  108  are shown located directly beneath the arches  150  and  160 , respectively.  
         [0114]    [0114]FIG. 16 shows the view of FIG. 15 as the rear left axle end  106  and the rear right axle end  108  are thrust upward toward the arches  150  and  160 , contacting the lateral side surfaces  148  and  158 , respectively, urging the rear left support column  116  and the rear right support column  114  apart from one another. Elastic deformation of rear left support column  116 , the rear right support column  114 , and the rear crossmember  166  that forms them is accompanied by pressure and friction between the rear left axle end  106  and the lateral surface  148 , and likewise between the rear right axle end  108  and the lateral surface  158 , which resists the vertical movement of the rear axle ends  106  and  108  relative to the rear support columns  116  and  114 .  
         [0115]    [0115]FIG. 17 shows the view of FIGS. 15 and 16 after the rear axle ends  106  and  108  have been thrust into contact with the arches  150  and  160  of the rear support columns  116  and  114 . So positioned, the axle ends are immobilized relative to the rear support columns  116  and  114  due to the aforementioned friction. As already indicated with reference to the front axle ends with reference to FIGS. 12, 13, and  14 , strong pulling, shoving, or prying is necessary to remove the rear axle ends  106  and  108  from this position.  
         [0116]    With continued reference to FIGS. 15, 16 and  17 , and also with reference to FIGS. 1, 12,  13  and  14 , the two types of elastic deformation are both important in immobilizing both the front axle  98  and the rear axle  100 . With particular reference to FIGS. 15, 16 and  17 , it will be appreciated that the bulk properties of the shoe bottom material that surrounds the support columns  110 ,  112 ,  114  and  116 , as well as the snugness with which that material surrounds the support columns, will influence the extent to which the friction between the axle ends  102 ,  104 ,  106  and  108  and the respective lateral surfaces  128 ,  138 ,  148  and  158  contributes to immobilizing the axles  98  and  100  within the wheel housings  78  and  80 .  
         [0117]    [0117]FIG. 20 shows a bottom sectional view of the heel portion  68  and the arch portion  70  of the shoe bottom  54  in the preferred embodiment of the roller shoe  40  in accordance with the present invention, including the front wheel housing  78  with the front wheel assembly  82  installed. The front right support column  110  with front prong  134 , rear prong  136  and lateral surface  138  forms the front right axle support  132 . Similarly, the front left support column  112 , with front prong  124 , rear prong  126  and lateral surface  128 , forms the front left axle support  122 . In like manner, the rear wheel housing  80  is shown with the rear wheel assembly  84  installed. The rear right support column  114  with front prong  154 , rear prong  156  and lateral surface  158  forms the rear right axle support  152 . Similarly, the rear left support column  116 , with front prong  144 , rear prong  146  and lateral surface  148 , forms the rear left axle support  142 .  
         [0118]    With continued reference to FIG. 20, the front right axle end  104  is lodged in the front right axle support  132  and the front left axle end  102  is lodged in the front left axle support  122 . The front right axle support  132  is formed to be elastically deformable such that the front right axle end  104  forcibly separates the front prong from the rear prong when thrust therebetween. The same cooperation occurs at the other axle supports. Additionally, the front crossmember  164  and the shoe bottom  54  surrounding the front wheel housing  78  hold the lateral surface  128  of the front left support column  112  and the lateral surface  138  of the front right support column  110  in elastically deformable mutual opposition, such that the front axle  98  forcibly separates them when thrust therebetween. Thus, the front wheel assembly  82  is held firmly in the front wheel housing  78 . Corresponding structures cooperate likewise to hold the rear wheel assembly  84  in the rear wheel housing  80 .  
         [0119]    With continued reference to FIG. 20, front wheel bearings  168  affix the front wheel  86  to the front axle  98 . The front wheel  86  forms a front wheel periphery  92 . The front axle  98  holds the front wheel  86  at a fixed location relative to the shoe bottom  54  and in a fixed orientation relative to the shoe bottom  54 , the location and orientation being determined by the position of the front left axle end  102  and the front right axle end  104  are held within the front left axle support  122  and the front right axle support  132 , respectively. Positioned and oriented in this manner, the front wheel  86  defines a sideways oriented, horizontally oriented front wheel axis of rotation as indicated by arrow Y1. The front wheel periphery  92  and the front wheel axis of rotation define a front wheel radius. Corresponding structures cooperate likewise to hold the rear wheel assembly  84  in the rear wheel housing  80  and to define the rear wheel axis of rotation as indicated by arrow Y2.  
         [0120]    The front axle  98  and rear axle  100  are metal, typically steel. The front wheel  86 , rear left wheel  88 , and rear right wheel  90  are formed of polyurethane or another suitably hard, resilient and durable material. The bearings are of a type generally available for the manufacture of machinery and sporting goods.  
         [0121]    While the foregoing detailed description has described several embodiments of a roller shoe in accordance with the present invention, it is to be understood that the above description is illustrative only and not limiting of the disclosed invention. Indeed, it will be appreciated that the embodiments discussed above and the virtually infinite embodiments that are not mentioned could easily be within the scope and spirit of the present invention. Thus, the present invention is to be limited only by the claims.