Patent Publication Number: US-11039659-B2

Title: Sole structure for article of footwear

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This non-provisional U.S. Patent Application claims priority under 35 U.S.C. § 119(e) to Provisional U.S. Patent Application No. 62/555,234 entitled “Sole Structure for Article of Footwear,” filed on Sep. 7, 2017. 
    
    
     FIELD 
     The present disclosure relates generally to an article of footwear and more particularly to a sole structure for an article of footwear. 
     BACKGROUND 
     This section provides background information related to the present disclosure and is not necessarily prior art. 
     Articles of footwear conventionally include an upper and a sole structure. The upper may be formed from any suitable material(s) to receive, secure, and support a foot on the sole structure. The upper may cooperate with laces, straps, or other fasteners to adjust the fit of the upper around the foot. A bottom portion of the upper, proximate to a bottom surface of the foot, attaches to the sole structure. 
     Sole structures generally include a layered arrangement extending between a ground surface and the upper. For example, a sole structure may include a midsole and an outsole. The midsole is generally disposed between the outsole and the upper and provides cushioning for the foot. The midsole may include a pressurized, fluid-filled chamber that compresses resiliently under an applied load to cushion the foot by attenuating ground-reaction forces. The outsole provides abrasion-resistance and traction with the ground surface and may be formed from rubber or other materials that impart durability and wear-resistance, as well as enhancing traction with the ground surface. 
     While known outsoles have proven acceptable for their intended purposes, a continuous need for improvement in the relevant art remains. For example, a need exists for an outsole that provides improved traction with a ground surface when forces having varying magnitude and/or direction are applied. A need also exists for an article of footwear having improved overall comfort and fit while providing such improved traction. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected configurations and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a perspective view of an article of footwear in accordance with principles of the present disclosure; 
         FIG. 2  is an exploded view of the article of footwear of  FIG. 1 ; 
         FIG. 3  is a perspective view of an outsole of the article of footwear of  FIG. 1  in accordance with principles of the present disclosure; 
         FIG. 4A  is a cross-sectional view of the outsole of  FIG. 3  taken through the line  4 A- 4 A and showing the outsole in a relaxed configuration; 
         FIG. 4B  is a cross-sectional view of the outsole of  FIG. 3  showing the outsole in a flexed configuration; 
         FIG. 5  is a perspective view of another outsole in accordance with principles of the present disclosure; 
         FIG. 6A  is a cross-sectional view of the outsole of  FIG. 5  taken through the line  6 A- 6 A and showing the outsole in a relaxed configuration; 
         FIG. 6B  is a cross-sectional view of the outsole of  FIG. 5  showing the outsole in a flexed configuration; 
         FIG. 7  is a perspective view of another outsole in accordance with principles of the present disclosure; 
         FIG. 8A  is a cross-sectional view of the outsole of  FIG. 7  taken through the line  8 A- 8 A and showing the outsole in a relaxed configuration; 
         FIG. 8B  is a cross-sectional view of the outsole of  FIG. 7  showing the outsole in a flexed configuration; 
         FIG. 9  is a perspective view of another outsole in accordance with principles of the present disclosure; 
         FIG. 10A  is a cross-sectional view of the outsole of  FIG. 9  taken through the line  10 A- 10 A and showing the outsole in a relaxed configuration; and 
         FIG. 10B  is a cross-sectional view of the outsole of  FIG. 9  showing the outsole in a flexed configuration. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the drawings. 
     DETAILED DESCRIPTION 
     Example configurations will now be described more fully with reference to the accompanying drawings. Example configurations are provided so that this disclosure will be thorough, and will fully convey the scope of the disclosure to those of ordinary skill in the art. Specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of configurations of the present disclosure. It will be apparent to those of ordinary skill in the art that specific details need not be employed, that example configurations may be embodied in many different forms, and that the specific details and the example configurations should not be construed to limit the scope of the disclosure. 
     The terminology used herein is for the purpose of describing particular exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. Additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” “attached to,” or “coupled to” another element or layer, it may be directly on, engaged, connected, attached, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” “directly attached to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     The terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections. These elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example configurations. 
     One aspect of the disclosure provides a sole structure for an article of footwear. The sole structure of the article of footwear includes a plate having a concave ground-engaging surface extending between a medial side of the plate and a lateral side of the plate and movable between a relaxed state and a flexed state. The concave surface has an increased radius when moved from the relaxed state to the flexed state. The sole structure also includes a first ground-engaging member extending from the plate proximate to the medial side of the plate. The sole structure further includes a second ground-engaging member extending from the plate proximate to the lateral side of the plate. The second ground-engaging member is spaced apart from the first ground-engaging member by a first distance when the plate is in the relaxed state and is spaced apart from the first ground engaging member by a second distance greater than the first distance when the plate is in the flexed state. 
     Implementations of the disclosure may include one or more of the following optional features. In some implementations, the plate of the sole structure includes a convex surface disposed on an opposite side of the plate than the concave surface. The convex surface may extend between the medial side and the lateral side. 
     In some examples, the sole structure includes a third ground-engaging member that extends from the plate in an area between the first ground-engaging member and the second ground-engaging member. The third ground-engaging member may include a substantially figure-eight shape. The third ground-engaging member may also include a first surface and a second surface that meet at an apex. In some examples, one of the first surface and the second surface is concave and the other of the first surface and the second surface is convex. 
     In some configurations, the first ground-engaging member extends from the plate along a first axis and the second ground-engaging member extends from the plate along a second axis, the first axis being convergent with the second axis when the plate is in the relaxed state. Here, the first axis may be substantially parallel with the second axis when the plate is in the flexed state. Additionally or alternatively, at least one of the first ground-engaging member and the second ground-engaging member may be disposed at a peripheral edge of the plate. 
     Another aspect of the disclosure provides a sole structure for an article of footwear. The sole structure includes a plate having a concave ground-engaging surface extending between a medial side of the plate and a lateral side of the plate and movable between a relaxed state and a flexed state. The concave surface has an increased radius when moved from the relaxed state to the flexed state. The sole structure also includes a first ground-engaging member extending from the plate proximate to the medial side of the plate along a first axis. The sole structure further includes a second ground-engaging member extending from the plate proximate to the lateral side of the plate along a second axis, the second axis being convergent with the first axis when the plate is in the relaxed state. 
     Implementations of the disclosure may include one or more of the following optional features. In some examples, the plate of the sole structure includes a convex surface disposed on an opposite side of the plate than the concave surface. The convex surface of the plate may extend between the medial side and the lateral side. 
     In some implementations, the sole structure includes a third ground-engaging member extending from the plate in an area between the first ground-engaging member and the second ground-engaging member. The third ground-engaging member may include a substantially figure-eight shape. Additionally or alternatively, the third ground-engaging member may include a first surface and a second surface that meet at an apex. One of the first surface and the second surface may be concave and the other of the first surface and the second surface may be convex. 
     In some configurations of the sole structure, the first ground-engaging member is spaced apart from the second ground-engaging member by a first distance when the plate is in the relaxed state and is spaced apart from the second ground engaging member by a second distance greater than the first distance when the plate is in the flexed state. Optionally, the first axis of the sole structure may be substantially parallel with the second axis when the plate is in the flexed state. Additionally or alternatively, at least one of the first ground-engaging member and the second ground-engaging member may be disposed at a peripheral edge of the plate. 
     Yet another aspect of the disclosure provides a sole structure for an article of footwear. The sole structure includes a plate having a concave ground-engaging surface extending between a medial side of the plate and a lateral side of the plate and movable between a relaxed state and a flexed state. The concave surface has an increased radius when moved from the relaxed state to the flexed state. The sole structure also includes a first ground-engaging member extending from the plate proximate to the medial side of the plate along a first axis. The sole structure further includes a second ground-engaging member extending from the plate proximate to the lateral side of the plate along a second axis, the second axis being substantially parallel with the first axis when the plate is in the flexed state. 
     Implementations of the disclosure may include one or more of the following optional features. In some configurations, the plate includes a convex surface disposed on an opposite side of the plate than the concave surface. In this configuration, the convex surface may extend between the medial side and the lateral side. 
     In some examples, the sole structure further includes a third ground-engaging member extending from the plate in an area between the first ground-engaging member and the second ground-engaging member. In this example, the third ground-engaging member may also include a substantially figure-eight shape. Optionally, the third ground-engaging member may further include a first surface and a second surface that meet at an apex. When a first surface and a second surface that meet at an apex, one of the first surface and the second surface may be concave and the other of the first surface and the second surface may be convex. 
     In some implementations, the first ground-engaging member is spaced apart from the second ground-engaging member by a first distance when the plate is in the relaxed state and is spaced apart from the second ground engaging member by a second distance greater than the first distance when the plate is in the flexed state. Additionally or alternatively, the first axis may be convergent with the second axis when the plate is in the relaxed state. In some examples, at least one of the first ground-engaging member and the second ground-engaging member are disposed at a peripheral edge of the plate. 
     The details of one or more implementations of the disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description, the drawings, and the claims. 
     Referring to  FIGS. 1 and 2 , an article of footwear  10  is provided and includes an upper  100  and a sole structure  200  attached to the upper  100 . The article of footwear  10  may be divided into one or more portions. The portions may include a forefoot portion  12 , a midfoot portion  14 , and a heel portion  16 . The forefoot portion  12  may correspond with toes and joints connecting metatarsal bones with phalanx bones of a foot. The midfoot portion  14  may correspond with an arch area of the foot, and the heel portion  16  may correspond with rear portions of the foot, including a calcaneus bone. The footwear  10  may include lateral and medial sides  18 ,  20 , respectively, corresponding with opposite sides of the footwear  10  and extending through the portions  12 ,  14 ,  16 . 
     The upper  100  includes interior surfaces that define an interior void  102  that receives and secures a foot for support on the sole structure  200 . An ankle opening  104  in the heel portion  16  may provide access to the interior void  102 . For example, the ankle opening  104  may receive a foot to secure the foot within the void  102  and facilitate entry and removal of the foot to and from the interior void  102 . In some examples, one or more fasteners  106  extend along the upper  100  to adjust a fit of the interior void  102  around the foot while concurrently accommodating entry and removal of the foot therefrom. The upper  100  may include apertures such as eyelets and/or other engagement features such as fabric or mesh loops that receive the fasteners  106 . The fasteners  106  may include laces, straps, cords, hook-and-loop, or any other suitable type of fastener. 
     The upper  100  may include a tongue portion  110  that extends between the interior void  102  and the fasteners  106 . The upper  100  may be formed from one or more materials that are stitched or adhesively bonded together to form the interior void  102 . Suitable materials of the upper may include, but are not limited, textiles, foam, leather, and synthetic leather. The materials may be selected and located to impart properties of durability, air-permeability, wear-resistance, flexibility, and comfort. 
     In some implementations, the sole structure  200  includes an outsole  210  and a midsole  226  arranged in a layered configuration. For example, the outsole  210  engages with a ground surface during use of the article of footwear  10  and the midsole  226  is disposed between the upper  100  and the outsole  210 . The midsole  226  may include a strobel and/or an energy absorbing member such as a foam member and/or a fluid-filled chamber (neither shown) disposed generally between the upper  100  and the outsole  210 . For example, the midsole  226  may include a strobel attached to the upper  100  via stitching and may include a foam material disposed between the strobel and the outsole  210 . While the midsole  226  may include both a strobel and an energy absorbing member, the midsole will be described hereinafter as including a strobel attached to the upper  100  with the outsole  210  being attached to the strobel and directly to a portion of the upper  100 , as shown in  FIG. 1 . 
     The sole structure  200  (e.g., the outsole  210  and the midsole  226 ) defines a longitudinal axis L. In some examples, the sole structure  200  may also incorporate additional layers such as an insole or sockliner (neither shown), which may reside within the interior void  102  of the upper  100  to receive a plantar surface of the foot to enhance the comfort of the footwear  10 . In some examples, a sidewall  230  surrounds a perimeter  232  of the outsole  210  and attaches the outsole  210  to a portion of the upper  100 . 
     Referring to  FIGS. 3-4B , the outsole  210  may attach to one or both of the upper  100  and the midsole  226  and may include an inner surface  212  and an opposite ground-engaging surface  214  disposed in a forefoot portion  216 , a midfoot portion  218 , or a heel portion  220  of the outsole  210  and extending from a lateral side  222  to a medial side  224  of the outsole  210 . The forefoot, midfoot, and heel portions  216 ,  218 ,  220  of the outsole  210  may correspond to, or otherwise be aligned with, the forefoot, the midfoot, and the heel portions  12 ,  14 ,  16 , respectively, along the axis L of the article of footwear  10 . The lateral and medial sides  222 ,  224  may correspond to, or otherwise be aligned with, the lateral and medial sides  18 ,  20 , respectively, of the article of footwear  10 . 
     The inner surface  212  and the ground-engaging surface  214  may be disposed along axes A 1  and A 2 , and may surround an axis A 3 . The axis A 1  may extend from the forefoot portion  12  to the heel portion  16  of the article of footwear  10 , and may correspond to, or otherwise be aligned with, the axis L, and the axis A 2  may extend from the lateral side  222  to the medial side  224  of the outsole  210 . The axis A 3  may extend through one of the forefoot, the midfoot, and the heel portions  216 ,  218 ,  220  in a direction transverse to (e.g., perpendicular) to the axes A 1  and A 2 . In some examples, the sidewall  230  extends from the perimeter  232  of the outsole  210  and attaches to the midsole  226  and/or to the upper  100 . The example of  FIG. 1  shows the outsole  210  attaching to the upper  100  proximate to a tip of the forefoot portion  12 . The outsole  210  generally provides abrasion-resistance and traction with the ground surface during use of the article of footwear  10 . The outsole  210  may be formed from one or more materials that impart durability and wear-resistance, as well as enhance traction with the ground surface. For example, rubber, plastic, and/or carbon fiber may form at least a portion of the outsole  210 . 
     The inner surface  212  may define an arc  250  extending from the lateral side  222  to the medial side  224  of the article of footwear  10 . In some implementations, the arc  250  defines a convex profile extending along the axis A 1  and having a radius of curvature R 1   r . For example, as illustrated in  FIG. 4A , in a resting configuration, the arc  250  may define a convex profile in a cross section taken through a plane intersecting the axis A 1  or extending along the axes A 2  and A 3 , whereby the convex profile faces the upper  100 . The radius of curvature R 1   r  may be between approximately three inches and ten inches. As used herein, “resting configuration” may include a configuration in which the force applied to the inner surface  212  in a direction extending along the axis A 3  or transverse to the axes A 1 , A 2  is less than a predetermined threshold. For example, in the resting configuration, the force applied to the inner surface  212  in a direction extending along the axis A 3  or transverse to the axes A 1 , A 2  may be less than three pounds-force. In some implementations, the force applied to the inner surface  212  in a direction extending along the axis A 3  or transverse to the axes A 1 , A 2  may be substantially equal to zero pounds-force in the resting configuration. 
     The ground-engaging surface  214  may define an arc  252  extending from the lateral side  222  to the medial side  224  of the article of footwear  10 . In some implementations, the arc  252  defines a concave profile extending along the axis A 1  and having a radius of curvature R 2   r . For example, as illustrated in  FIG. 4A , in the resting configuration, the arc  252  may define a concave profile in a cross section taken through a plane intersecting the axis A 1  or extending along the axes A 2  and A 3 . In some implementations, the arc  252  is substantially parallel to the arc  250 . In this regard, the radius of curvature R 2   r  of the arc  252  may be between approximately two inches and ten inches. 
     With continued reference to  FIGS. 3-4B , the outsole  210  may include one or more central ground-engaging members  254 , and a flange  256  having one or more peripheral ground-engaging members  258 . The central ground-engaging member(s)  254  may include an inner surface  255 - 1  and an outer surface  255 - 2  extending from the ground-engaging surface  214  to a ground-engaging edge  259 . The inner and outer surfaces  255 - 1 ,  255 - 2  may extend in a direction transverse to the axes A 1 , A 2 . In some implementations, the inner surface  255 - 1  is disposed at an angle σ (e.g., greater than approximately five degrees and less than approximately one hundred seventy-five degrees) relative to the outer surface  255 - 2  such that the ground-engaging edge  259  defines a peak or ridge of the central ground-engaging member  254 . 
     As illustrated in  FIG. 3 , in some implementations, the central ground-engaging member  254  includes a forward lobe  261 - 1  and a rearward lobe  261 - 2 . For example, the inner and outer surfaces  255 - 1 ,  255 - 2  may define the forward lobe  261 - 1  and the rearward lobe  261 - 2 . The forward and rearward lobes  261 - 1 ,  261 - 2  may define a substantially figure-eight shaped construct disposed in the forefoot portion  216  of the outsole  210 . While the forward and rearward lobes  261 - 1 ,  261 - 2  are each illustrated as defining a rectangular or diamond shape, it will be appreciated that each of the forward and rearward lobes  261 - 1 ,  261 - 2  may define a triangular, circular, or other suitable shape within the scope of the present disclosure. 
     The ground-engaging edge  259  of the forward lobe  261 - 1  may include a forward-medial portion  259 - 1 , a forward-lateral portion  259 - 2  extending from the forward-medial portion  259 - 1 , a rearward-lateral portion  259 - 3  extending from the forward-lateral portion  259 - 2 , and a rearward-medial portion  259 - 4  extending from the rearward-lateral portion  259 - 3  to the forward-medial portion  259 - 1 . As previously described, while the forward-medial portion  259 - 1 , the forward-lateral portion  259 - 2 , the rearward-lateral portion  259 - 3 , and the rearward-medial portion  259 - 4  are illustrated as collectively defining a rectangular or diamond shape, it will be appreciated that the forward-medial portion  259 - 1 , the forward-lateral portion  259 - 2 , the rearward-lateral portion  259 - 3 , and the rearward-medial portion  259 - 4  may collectively define a triangular, circular, or other suitable shape within the scope of the present disclosure. 
     The ground-engaging edge  259  of the rearward lobe  261 - 2  may include a forward-medial portion  259 - 5 , a forward-lateral portion  259 - 6  extending from the forward-medial portion  259 - 5 , a rearward-lateral portion  259 - 7  extending from the forward-lateral portion  259 - 6 , and a rearward-medial portion  259 - 8  extending from the rearward-lateral portion  259 - 7  to the forward-medial portion  259 - 5 . As previously described, while the forward-medial portion  259 - 5 , the forward-lateral portion  259 - 6 , the rearward-lateral portion  259 - 7 , and the rearward-medial portion  259 - 8  are illustrated as collectively defining a rectangular or diamond shape, it will be appreciated that the forward-medial portion  259 - 5 , the forward-lateral portion  259 - 6 , the rearward-lateral portion  259 - 7 , and the rearward-medial portion  259 - 8  may collectively define a triangular, circular, or other suitable shape within the scope of the present disclosure. 
     The ground-engaging edge  259  of the central ground-engaging member  254  may taper toward or away from the ground engaging surface  214  such that a distance H between the ground-engaging surface  214  and the ground-engaging edge  259 , in a direction extending substantially parallel to the axis A 3 , varies along the length of the ground-engaging edge  259 . In some implementations, the distance H between the ground-engaging surface  214  and the ground-engaging edge  259  defined by the forward-most location of the ground-engaging edge  259  (e.g., a location of the ground-engaging edge  259  disposed closest to the forefoot portion  216 ) or a rearward-most location of the ground-engaging edge  259  (e.g., a location of the ground-engaging edge  259  disposed closest to the heel portion  220 ) is greater than the distance H between the ground-engaging surface  214  and the ground-engaging edge  259  defined by a central location of the ground-engaging edge  259  (e.g., a location of the ground-engaging edge  259  disposed between the forward-most and rearward-most locations of the ground-engaging edge  259 ). 
     In some implementations, the forward-medial portion  259 - 1  tapers toward the ground engaging surface  214  in a direction extending toward the medial side  224  or heel portion  220 . In some implementations, the forward-medial portion  259 - 1  tapers toward the ground engaging surface  214  in a direction extending from the forward-lateral portion  259 - 2  to the rearward-medial portion  259 - 4 . 
     The forward-lateral portion  259 - 2  may taper toward the ground engaging surface  214  in a direction extending toward the lateral side  222  or heel portion  220 . In some implementations, the forward-lateral portion  259 - 2  tapers toward the ground engaging surface  214  in a direction extending from the forward-medial portion  259 - 1  to the rearward-lateral portion  259 - 3 . 
     The rearward-lateral portion  259 - 3  may taper toward the ground engaging surface  214  in a direction extending toward the medial side  224  or heel portion  220 . In some implementations, the rearward-lateral portion  259 - 3  tapers toward the ground engaging surface  214  in a direction extending from the forward-lateral portion  259 - 2  to the rearward-medial portion  259 - 4 . 
     The rearward-medial portion  259 - 4  may taper toward the ground engaging surface  214  in a direction extending toward the lateral side  222  or heel portion  220 . In some implementations, the rearward-medial portion  259 - 4  tapers toward the ground engaging surface  214  in a direction extending from the forward-medial portion  259 - 1  to the rearward-lateral portion  259 - 3 . 
     The forward-medial portion  259 - 5  may taper toward the ground engaging surface  214  in a direction extending toward the lateral side  222  or forefoot portion  216 . In some implementations, the forward-medial portion  259 - 5  tapers toward the ground engaging surface  214  in a direction extending from the rearward-medial portion  259 - 8  to the forward-lateral portion  259 - 6 . 
     The forward-lateral portion  259 - 6  may taper toward the ground engaging surface  214  in a direction extending toward the medial side  224  or forefoot portion  216 . In some implementations, the forward-lateral portion  259 - 6  tapers toward the ground engaging surface  214  in a direction extending from the rearward-lateral portion  259 - 7  to the forward-medial portion  259 - 5 . 
     The rearward-lateral portion  259 - 7  may taper toward the ground engaging surface  214  in a direction extending toward the lateral side  222  or forefoot portion  216 . In some implementations, the rearward-lateral portion  259 - 7  tapers toward the ground engaging surface  214  in a direction extending from the rearward-medial portion  259 - 8  to the forward-lateral portion  259 - 6 . 
     The rearward-medial portion  259 - 8  may taper toward the ground engaging surface  214  in a direction extending toward the medial side  224  or forefoot portion  216 . In some implementations, the rearward-medial portion  259 - 8  tapers toward the ground engaging surface  214  in a direction extending from the rearward-lateral portion  259 - 7  to the forward-medial portion  259 - 5 . 
     The flange  256  may be disposed proximate to at least a portion of the perimeter  232  of the outsole  210 . In this regard, the flange  256  may extend around at least a portion of the ground-engaging surface  214 . For example, the flange  256  may surround the ground-engaging surface  214 . As illustrated in  FIG. 4A , in some implementations, the flange  256  extends from the outsole  210  and away from the inner surface  212  along an axis A 4  in a cross-section taken along the axis A 3 . The axis A 4  may define an angle α relative to the axis A 1 . The angle α may be between approximately zero degrees and approximately forty degrees. In this regard, the angle α may vary between approximately zero degrees and approximately forty degrees depending on the location at which the cross section is taken, such that the flange  256  tapers inwardly (e.g., toward a center of the outsole  210 ) or otherwise defines a portion of a frustoconical shape. For example, as illustrated in  FIG. 4A , in a cross section taken through the axes A 2 , A 3 , the angle α may be between approximately two degrees and approximately ten degrees in the resting configuration. In some implementations, the axis A 4  may extend in a direction substantially parallel (+/−five degrees) to the radius of curvature R 2  of the ground-engaging surface  214  in the resting configuration. 
     The peripheral ground-engaging member(s)  258  may extend from the flange  256  or the ground-engaging surface  214 . As illustrated in  FIG. 4A , in some implementations, the peripheral ground-engaging member(s)  258  extend from the flange  256  and away from the ground-engaging surface  214  along the axis A 4  in a cross-section taken along the axis A 3 , such that a distal end  260  of the central ground-engaging member(s)  254  and a distal end  262  of the peripheral ground-engaging member(s)  258  define a distance X extending therebetween. In the resting configuration, the distance X may be between approximately one millimeter and approximately ten millimeters. In some implementations, the distance X is substantially equal to five millimeters. 
     During operation or use of the article of footwear  10  (e.g., the outsole  210 ), a force may be applied to the outsole  210 . For example, as illustrated in  FIG. 4B , a wearer&#39;s foot may apply a force F 1  to the inner surface  212  of the outsole  210 . At least a portion of the force F 1  may extend along (e.g., substantially parallel to) one or both of the radii of curvature R 1   r , R 2   r  of the outsole  210 . When the portion of the force F 1  extending along one or both of the radii of curvature R 1   r , R 2   r  is greater than a predetermined threshold (e.g., greater than approximately twenty pounds-force), the outsole may flex, causing one or both of the radii of curvature R 1   r , R 2   r  to increase until the outsole  210  is in a flexed configuration (e.g.,  FIG. 4B ). In this regard, in the flexed configuration, the inner surface  212  and the ground-engaging surface  214  may define radii of curvature R 1   f , R 2   f  that are greater than the corresponding radii of curvature R 1   r , R 2   r  defined by the resting configuration. In some implementations, the inner surface  212  or the ground-engaging surface  214  may be substantially planar in the flexed configuration, such that the radii of curvature R 1   f , R 2   f  are substantially infinite. In the flexed configuration, the outsole  210  may be biased towards the resting configuration by a reaction force F 2  produced by the ground and extending in a direction opposite the force F 1 . 
     Accordingly, as the outsole  210  flexes from the resting configuration to the flexed configuration, one or both of the distance X and the angle α may decrease. For example, in the flexed configuration, the distance X may be less than five millimeters, and the angle α may be less than five degrees. In some implementations, the distance X is substantially equal to zero millimeters and the angle α is substantially equal to zero degrees in the flexed configuration. In this regard, the axis A 4  corresponding to at least a portion of the flange  256  and one or more of the peripheral ground-engaging members  258  may be substantially parallel to the axis A 3  in the flexed configuration. For example, axis A 4  corresponding to the portion of the flange  256  aligned with the lateral or medial sides  222 ,  224 , or the peripheral ground-engaging members  258  disposed along the lateral or medial sides  222 ,  224 , may be substantially parallel to the axis A 3  in the flexed configuration. Accordingly, in the flexed configuration, the flange  256 , the ground-engaging members  258 , or the ground-engaging member(s)  254  may provide improved traction between the footwear  10  and the ground. For example, in the resting configuration, the rearward-lateral portion  259 - 3 , rearward-medial portion  259 - 4 , forward-medial portion  259 - 5 , or forward-lateral portion  259 - 6  of the ground-engaging edge  259  may be disengage from the ground, such that the ground and the rearward-lateral portion  259 - 3 , rearward-medial portion  259 - 4 , forward-medial portion  259 - 5 , or forward-lateral portion  259 - 6  of the ground-engaging edge  259  define a gap (e.g., a void), whereas in the flexed configuration, the rearward-lateral portion  259 - 3 , rearward-medial portion  259 - 4 , forward-medial portion  259 - 5 , or forward-lateral portion  259 - 6  of the ground-engaging edge  259  may engage the ground to provide better traction between the ground-engaging member(s)  254  and the ground. 
     The material of the outsole  210  causes the outsole  210  to be biased into the relaxed configuration. As such, when the force applied to the outsole  210  is removed, the outsole  210  automatically returns to the relaxed configuration. Namely, the outsole  210  may be formed from a relatively rigid but flexible material that causes the outsole  210  to automatically return to the relaxed configuration when the force applied to the outsole  210  is removed. As such, the material of the outsole  210  along with the concave profile of the ground-engaging surface  214  causes the outsole  210  to automatically snap back from the flexed configuration to the relaxed configuration and, in so doing, aide in propelling the wearer. 
     Referring to  FIGS. 5-6B , another outsole  210   a  for use with the article of footwear  10  is illustrated. The outsole  210   a  may be substantially similar to the outsole  210  except as otherwise shown or described herein. Accordingly, the structure and function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “a”) are used to identify those features that have been modified. 
     The outsole  210   a  may include one or more central ground-engaging members  254   a , the flange  256 , and the one or more peripheral ground-engaging members  258 . The central ground-engaging member(s)  254   a  may include an inner surface  255 - 1   a  and an outer surface  255 - 2   a  extending from the ground-engaging surface  214  to a ground-engaging edge  259   a . The inner and outer surfaces  255 - 1   a ,  255 - 2   a  may extend in a direction transverse to the axes A 1 , A 2 . In some implementations, the inner surface  255 - 1   a  is disposed at an angle σa (e.g., greater than approximately five degrees and less than approximately one hundred seventy-five degrees) relative to the outer surface  255 - 2   a  such that the ground-engaging edge  259   a  defines a peak or ridge of the central ground-engaging member  254   a.    
     As illustrated in  FIG. 5 , in some implementations, the central ground-engaging member  254   a  includes a forward lobe  261 - 1   a  and a rearward lobe  261 - 2   a . For example, the inner and outer surfaces  255 - 1   a ,  255 - 2   a  may define the forward lobe  261 - 1   a  and the rearward lobe  261 - 2   a . The forward and rearward lobes  261 - 1   a ,  261 - 2   a  may define a substantially figure-eight shaped construct disposed in the forefoot portion  12 . While the forward and rearward lobes  261 - 1   a ,  261 - 2   a  are each illustrated as defining a rectangular or diamond shape, it will be appreciated that each of the forward and rearward lobes  261 - 1   a ,  261 - 2   a  may define a triangular, circular, or other suitable shape within the scope of the present disclosure. 
     The ground-engaging edge  259   a  of the forward lobe  261 - 1   a  may include a forward-medial portion  259 - 1   a , a forward-lateral portion  259 - 2   a  extending from the forward-medial portion  259 - 1   a , a rearward-lateral portion  259 - 3   a  extending from the forward-lateral portion  259 - 2   a , and a rearward-medial portion  259 - 4   a  extending from the rearward-lateral portion  259 - 3   a  to the forward-medial portion  259 - 1   a . As previously described, while the forward-medial portion  259 - 1   a , the forward-lateral portion  259 - 2   a , the rearward-lateral portion  259 - 3   a , and the rearward-medial portion  259 - 4   a  are illustrated as collectively defining a rectangular or diamond shape, it will be appreciated that the forward-medial portion  259 - 1   a , the forward-lateral portion  259 - 2   a , the rearward-lateral portion  259 - 3   a , and the rearward-medial portion  259 - 4   a  may collectively define a triangular, circular, or other suitable shape within the scope of the present disclosure. 
     The ground-engaging edge  259   a  of the rearward lobe  261 - 2   a  may include a forward-medial portion  259 - 5   a , a forward-lateral portion  259 - 6   a  extending from the forward-medial portion  259 - 5   a , a rearward-lateral portion  259 - 7   a  extending from the forward-lateral portion  259 - 6   a , and a rearward-medial portion  259 - 8   a  extending from the rearward-lateral portion  259 - 7   a  to the forward-medial portion  259 - 5   a . As previously described, while the forward-medial portion  259 - 5   a , the forward-lateral portion  259 - 6   a , the rearward-lateral portion  259 - 7   a , and the rearward-medial portion  259 - 8   a  are illustrated as collectively defining a rectangular or diamond shape, it will be appreciated that the forward-medial portion  259 - 5   a , the forward-lateral portion  259 - 6   a , the rearward-lateral portion  259 - 7   a , and the rearward-medial portion  259 - 8   a  may collectively define a triangular, circular, or other suitable shape within the scope of the present disclosure. 
     The ground-engaging edge  259   a  of the central ground-engaging member  254   a  may taper toward or away from the ground engaging surface  214  such that a distance Ha between the ground-engaging surface  214  and the ground-engaging edge  259   a , in a direction extending substantially parallel to the axis A 3 , varies along the length of the ground-engaging edge  259   a . In some implementations, the distance Ha between the ground-engaging surface  214  and the ground-engaging edge  259   a  defined by a medial-most location of the ground-engaging edge  259   a  (e.g., a location of the ground-engaging edge  259   a  disposed closest to the medial side  224 ) or a lateral-most location of the ground-engaging edge  259   a  (e.g., a location of the ground-engaging edge  259  disposed closest to the lateral side  222 ) is greater than the distance Ha between the ground-engaging surface  214  and the ground-engaging edge  259   a  defined by a central location of the ground-engaging edge  259   a  (e.g., a location of the ground-engaging edge  259   a  disposed between the forward-most, rearward-most, lateral-most, and medial-most locations of the ground-engaging edge  259   a ). 
     In some implementations, the forward-medial portion  259 - 1   a  tapers toward the ground engaging surface  214  in a direction extending toward the lateral side  222  or forefoot portion  216 . In some implementations, the forward-medial portion  259 - 1   a  tapers toward the ground engaging surface  214  in a direction extending from the rearward-medial portion  259 - 4   a  to the forward-lateral portion  259 - 2   a.    
     The forward-lateral portion  259 - 2   a  may taper toward the ground engaging surface  214  in a direction extending toward the medial side  224  or forefoot portion  216 . In some implementations, the forward-lateral portion  259 - 2   a  tapers toward the ground engaging surface  214  in a direction extending from the rearward-lateral portion  259 - 3   a  to the forward-medial portion  259 - 1   a.    
     The rearward-lateral portion  259 - 3   a  may taper toward the ground engaging surface  214  in a direction extending toward the medial side  224  or heel portion  220 . In some implementations, the rearward-lateral portion  259 - 3   a  tapers toward the ground engaging surface  214  in a direction extending from the forward-lateral portion  259 - 2   a  to the rearward-medial portion  259 - 4   a.    
     The rearward-medial portion  259 - 4   a  may taper toward the ground engaging surface  214  in a direction extending toward the lateral side  222  or heel portion  220 . In some implementations, the rearward-medial portion  259 - 4   a  tapers toward the ground engaging surface  214  in a direction extending from the forward-medial portion  259 - 1   a  to the rearward-lateral portion  259 - 3   a.    
     The forward-medial portion  259 - 5   a  may taper toward the ground engaging surface  214  in a direction extending toward the lateral side  224  or forefoot portion  216 . In some implementations, the forward-medial portion  259 - 5   a  tapers toward the ground engaging surface  214  in a direction extending from the rearward-medial portion  259 - 8   a  to the forward-lateral portion  259 - 6   a.    
     The forward-lateral portion  259 - 6   a  may taper toward the ground engaging surface  214  in a direction extending toward the medial side  224  or forefoot portion  216 . In some implementations, the forward-lateral portion  259 - 6   a  tapers toward the ground engaging surface  214  in a direction extending from the rearward-lateral portion  259 - 7   a  to the forward-medial portion  259 - 5   a.    
     The rearward-lateral portion  259 - 7   a  may taper toward the ground engaging surface  214  in a direction extending toward the lateral side  222  or forefoot portion  216 . In some implementations, the rearward-lateral portion  259 - 7   a  tapers toward the ground engaging surface  214  in a direction extending from the rearward-medial portion  259 - 8   a  to the forward-lateral portion  259 - 6   a.    
     The rearward-medial portion  259 - 8   a  may taper toward the ground engaging surface  214  in a direction extending toward the medial side  224  or forefoot portion  216 . In some implementations, the rearward-medial portion  259 - 8   a  tapers toward the ground engaging surface  214  in a direction extending from the rearward-lateral portion  259 - 7   a  to the forward-medial portion  259 - 5   a.    
     The flange  256   a  may be disposed proximate to at least a portion of a perimeter  232  of the outsole  210   a . In some implementations, the flange  256   a  defines a gap or void  263  disposed along the medial side  224 . In this regard, the flange  256   a  may extend from a proximal end  264  to a distal end  265  such that the ground-engaging surface  214  extends to the medial side  224 . The proximal and distal ends  264 ,  265  may be disposed on the medial side  224  and define the void  263  therebetween. 
     Referring to  FIGS. 7-8B , another outsole  210   b  for use with the article of footwear  10  is illustrated. The outsole  210   b  may be substantially similar to the outsole  210  except as otherwise shown or described herein. Accordingly, the structure and function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “b”) are used to identify those features that have been modified. 
     The outsole  210   b  may include one or more central ground-engaging members  254   b , the flange  256 , and the one or more of the peripheral ground-engaging members  258 . The central ground-engaging member(s)  254   b  may include an inner surface  255 - 1   b  and an outer surface  255 - 2   b  extending from the ground-engaging surface  214  to a ground-engaging edge  259   b . The inner and outer surfaces  255 - 1   b ,  255 - 2   b  may extend in a direction transverse to the axes A 1 , A 2 . In some implementations, the inner surface  255 - 1   b  is disposed at an angle σb (e.g., greater than approximately five degrees and less than approximately one hundred seventy-five degrees) relative to the outer surface  255 - 2   b  such that the ground-engaging edge  259   b  defines a peak or ridge of the central ground-engaging member  254   b . In some implementations, the inner surface  255 - 1   b  is concave and the outer surface  255 - 1   b  is convex. 
     As illustrated in  FIG. 7 , in some implementations, the central ground-engaging members  254   b  (e.g., the ground-engaging edge  259   b ) each define a substantially V-shaped construct having a proximal end  266 , a distal end  268 , and an apex  270  disposed between the proximal and distal ends  266 ,  268 . For example, the ground-engaging edge  259   b  may taper towards the ground-engaging surface  214  from the apex  270  to the proximal end  266  and from the apex  270  to the distal end  268 . 
     In some implementations, the central ground-engaging members  254   b  include a first set  274  of ground-engaging members  254   b  and a second set  276  of ground-engaging members  254   b . The second set  276  of ground engaging members  254   b  may be disposed between the first set  274  and the heel portion  220  of the outsole  210   b . The proximal and distal ends  266 ,  268  of each ground-engaging member  254   b  of the first set  274  of ground-engaging members  254   b  may be disposed between the apex  270  of the corresponding ground-engaging member  254   b  and the second set  276  of ground-engaging members  254 , while the proximal and distal ends  266 ,  268  of each ground-engaging member  254   b  of the second set  276  of ground-engaging members  254   b  may be disposed between the apex  270  of the corresponding ground-engaging member  254   b  and the first set  274  of ground-engaging members  254   b . In some implementations, the apex  270  of at least one of the ground-engaging members  254   b  of the first set  274  of ground-engaging members  254   b  and the apex  270  of at least one of the ground-engaging members  254   b  of the second set  276  of ground-engaging members  254   b  is disposed along the axis A 1  of the outsole  210   b . As used herein, the “apex” may refer to the location on the ground-engaging member  254   b  disposed the greatest distance from the ground-engaging surface  214 . In this regard, as illustrated in  FIG. 8A , each ground-engaging member  254   b  may extend from the ground-engaging surface  214  to the respective apex  270  along an axis A 5 . In some implementations, the axis A 5  may extend in a direction substantially perpendicular to the radii of curvature R 1   r , R 2   r . Accordingly, the axis A 5  of one or more of the ground-engaging members  254   b  may define an angle β relative to the axis A 3 . 
     During operation or use of the article of footwear  10  (e.g., the outsole  210   b ), the force F 1  may be applied to the outsole  210   b , as previously described, until the outsole  210   b  is in a flexed configuration (e.g.,  FIG. 8B ). As the outsole  210   b  flexes from the resting configuration to the flexed configuration, one or more of the distance X, the angle α, and the angle β may decrease. For example, in the flexed configuration, the distance X may be less than approximately five millimeters, and the angles α or β may be less than approximately five degrees. In some implementations, the distance X is substantially equal to zero millimeters and the angles α and β are substantially equal to zero degrees in the flexed configuration. In this regard, the axes A 4  and A 5  corresponding to at least a portion of the flange  256  and one or more of the ground-engaging members  254   b , respectively, may be substantially parallel to the axis A 3  in the flexed configuration. Accordingly, in the flexed configuration, the flange  256 , the ground-engaging members  258 , or the ground-engaging members  254   b  may provide improved traction between the outsole  210   b  and the ground. 
     Referring to  FIGS. 9-10B , another outsole  210   c  for use with the article of footwear  10  is illustrated. The outsole  210   c  may be substantially similar to the outsole  210  except as otherwise shown or described herein. Accordingly, the structure and function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “c”) are used to identify those features that have been modified. 
     The outsole  210   c  may include the flange  256  having one or more peripheral ground-engaging members  258   c . The peripheral ground-engaging member(s)  258   c  may extend from the flange  256  or the ground-engaging surface  214  in a direction transverse to the axes A 1 , A 2 . For example, as illustrated in  FIG. 10A , the peripheral ground-engaging member(s)  258   c  may extend from the flange  256  and away from the ground-engaging surface  214  along the axis A 4  in a cross section taken perpendicular to the axis A 1 , such that a central portion  280  of the ground-engaging surface  214  and a distal end  262   c  of the peripheral ground-engaging member(s)  258   c  define a distance Xc extending therebetween. In some implementations, the distal end  262   c  is substantially planar. In the resting configuration, the distal ends  262   c  of the peripheral ground-engaging members  254   c  may extend in a direction transverse to a plane defined by the axes A 1 , A 2 . 
     As illustrated in  FIG. 9 , in some implementations, the peripheral ground-engaging members  254   c  include a pair of surfaces  282  extending from the ground-engaging surface  214  to the distal end  262   c . In some implementations, the surface  282  defines a generally horizontally extending concave arc  284  and a generally vertically-extending concave arc  286 . The pair of surfaces  282  may define an edge  286  tapering towards the ground-engaging surface  214  from the distal end  262   c . In some implementations, the edge  286  is concave. 
     The outsole  210   c  may include four peripheral ground-engaging members  254   c  disposed in the forefoot portion  216  of the outsole  210   c . In some implementations, the edge  286  of a first of the peripheral ground-engaging members  254   c  is aligned with the edge  286  of a second of the peripheral ground-engaging members  254   b , and the edge  286  of a third of the peripheral ground-engaging members  254   c  is aligned with the edge  286  of a fourth of the peripheral ground-engaging members  254   c . In this regard, the edges  286  of the first and second peripheral ground-engaging members  254   c  may define, or otherwise be aligned with, a line  288 , and the edges  286  of the third and fourth peripheral ground-engaging members  254   c  may define, or otherwise be aligned with, a line  290 . The line  288  may intersect the line  290  proximate to the central portion  280  of the ground-engaging surface  214 , such that the line  288  and the line  290  define an angle θ therebetween. The angle θ may be between approximately sixty degrees and approximately one hundred twenty degrees. In some implementation, the angle θ is substantially equal to ninety degrees. 
     During operation or use of the article of footwear  10  (e.g., the outsole  210   c ), the force F 1  may be applied to the outsole  210   c , as previously described, until the outsole  210   c  is in a flexed configuration (e.g.,  FIG. 10B ). As the outsole  210   c  flexes from the resting configuration to the flexed configuration, one or both of the distance Xc and the angle α may decrease. For example, in the flexed configuration, the distance Xc may be less than approximately five millimeters, and the angle α may be less than approximately five degrees. In this regard, the axis A 4  may be substantially parallel to the axis A 3  in the flexed configuration, such that the distal ends  262   c  of the peripheral ground-engaging members  254   c  are substantially coplanar. Accordingly, in the flexed configuration, the flange  256  or the ground-engaging members  254   c  may provide improved traction between the footwear  10  and the ground. 
     The following Clauses provide exemplary configurations of the sole structure and article of footwear described above. 
     Clause 1. A sole structure for an article of footwear, the sole structure comprising (i) a plate having a concave ground-engaging surface extending between a medial side of the plate and a lateral side of the plate and movable between a relaxed state and a flexed state, the concave ground-engaging surface having an increased radius when moved from the relaxed state to the flexed state; (ii) a first ground-engaging member extending from the plate proximate to the medial side of the plate; and (iii) a second ground-engaging member extending from the plate proximate to the lateral side of the plate, the second ground-engaging member being spaced apart from the first ground-engaging member by a first distance when the plate is in the relaxed state and being spaced apart from the first ground-engaging member by a second distance greater than the first distance when the plate is in the flexed state. 
     Clause 2. The sole structure of Clause 1, wherein the plate includes a convex surface disposed on an opposite side of the plate than the concave ground-engaging surface. 
     Clause 3. The sole structure of Clause 2, wherein the convex surface extends between the medial side and the lateral side. 
     Clause 4. The sole structure of any of the preceding clauses, further comprising a third ground-engaging member extending from the plate in an area between the first ground-engaging member and the second ground-engaging member. 
     Clause 5. The sole structure of Clause 4, wherein the third ground-engaging member includes a substantially figure-eight shape. 
     Clause 6. The sole structure of Clause 4, wherein the third ground-engaging member includes a first surface and a second surface that meet at an apex. 
     Clause 7. The sole structure of Clause 6, wherein one of the first surface and the second surface is concave and the other of the first surface and the second surface is convex. 
     Clause 8. The sole structure of any of the preceding clauses, wherein the first ground-engaging member extends from the plate along a first axis and the second ground-engaging member extends from the plate along a second axis, the first axis being convergent with the second axis when the plate is in the relaxed state. 
     Clause 9. The sole structure of Clause 8, wherein the first axis is substantially parallel with the second axis when the plate is in the flexed state. 
     Clause 10. The sole structure of any of the preceding clauses, wherein at least one of the first ground-engaging member and the second ground-engaging member are disposed at a peripheral edge of the plate. 
     Clause 11. A sole structure for an article of footwear, the sole structure comprising (i) a plate having a concave ground-engaging surface extending between a medial side of the plate and a lateral side of the plate and movable between a relaxed state and a flexed state, the concave ground-engaging surface having an increased radius when moved from the relaxed state to the flexed state; (ii) a first ground-engaging member extending from the plate proximate to the medial side of the plate along a first axis; and (iii) a second ground-engaging member extending from the plate proximate to the lateral side of the plate along a second axis, the second axis being convergent with the first axis when the plate is in the relaxed state. 
     Clause 12. The sole structure of Clause 11, wherein the plate includes a convex surface disposed on an opposite side of the plate than the concave ground-engaging surface. 
     Clause 13. The sole structure of Clause 12, wherein the convex surface extends between the medial side and the lateral side. 
     Clause 14. The sole structure of any of the preceding clauses, further comprising a third ground-engaging member extending from the plate in an area between the first ground-engaging member and the second ground-engaging member. 
     Clause 15. The sole structure of Clause 14, wherein the third ground-engaging member includes a substantially figure-eight shape. 
     Clause 16. The sole structure of Clause 14, wherein the third ground-engaging member includes a first surface and a second surface that meet at an apex. 
     Clause 17. The sole structure of Clause 16, wherein one of the first surface and the second surface is concave and the other of the first surface and the second surface is convex. 
     Clause 18. The sole structure of any of the preceding clauses, wherein the first ground-engaging member is spaced apart from the second ground-engaging member by a first distance when the plate is in the relaxed state and is spaced apart from the second ground-engaging member by a second distance greater than the first distance when the plate is in the flexed state. 
     Clause 19. The sole structure of any of the preceding clauses, wherein the first axis is substantially parallel with the second axis when the plate is in the flexed state. 
     Clause 20. The sole structure of any of the preceding clauses, wherein at least one of the first ground-engaging member and the second ground-engaging member are disposed at a peripheral edge of the plate. 
     Clause 21. A sole structure for an article of footwear, the sole structure comprising (i) a plate having a concave ground-engaging surface extending between a medial side of the plate and a lateral side of the plate and movable between a relaxed state and a flexed state, the concave ground-engaging surface having an increased radius when moved from the relaxed state to the flexed state; (ii) a first ground-engaging member extending from the plate proximate to the medial side of the plate along a first axis; and (iii) a second ground-engaging member extending from the plate proximate to the lateral side of the plate along a second axis, the second axis being substantially parallel with the first axis when the plate is in the flexed state. 
     Clause 22. The sole structure of Clause 21, wherein the plate includes a convex surface disposed on an opposite side of the plate than the concave ground-engaging surface. 
     Clause 23. The sole structure of Clause 22, wherein the convex surface extends between the medial side and the lateral side. 
     Clause 24. The sole structure of any of the preceding clauses, further comprising a third ground-engaging member extending from the plate in an area between the first ground-engaging member and the second ground-engaging member. 
     Clause 25. The sole structure of Clause 24, wherein the third ground-engaging member includes a substantially figure-eight shape. 
     Clause 26. The sole structure of Clause 24, wherein the third ground-engaging member includes a first surface and a second surface that meet at an apex. 
     Clause 27. The sole structure of Clause 26, wherein one of the first surface and the second surface is concave and the other of the first surface and the second surface is convex. 
     Clause 28. The sole structure of any of the preceding clauses, wherein the first ground-engaging member is spaced apart from the second ground-engaging member by a first distance when the plate is in the relaxed state and is spaced apart from the second ground-engaging member by a second distance greater than the first distance when the plate is in the flexed state. 
     Clause 29. The sole structure of any of the preceding clauses, wherein the first axis is convergent with the second axis when the plate is in the relaxed state. 
     Clause 30. The sole structure of any of the preceding clauses, wherein at least one of the first ground-engaging member and the second ground-engaging member are disposed at a peripheral edge of the plate. 
     The foregoing description has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular configuration are generally not limited to that particular configuration, but, where applicable, are interchangeable and can be used in a selected configuration, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.