Footwear sole structure with replaceable friction-modifying material sections for dancing

Abstract

A footwear sole structure has shallow recessed regions that receive user-replaceable friction-modifying sections. Each section, when installed, protrudes beyond adjacent outsole surfaces. Preferred recess depths are about two millimeters or less, typically about one millimeter; sections are about two to three millimeters thick and protrude at least 0.5 millimeter. The footwear remains wearable with a section absent due to the shallow recess and adjacent outsole surfaces configured to provide ground contact. Adhesive is preferred — e.g., pressure-sensitive adhesive or transfer film — to affix the sections to engineered adhesion surfaces distinct from surrounding outsole regions; and sections may include indexing indicia or non-rotationally symmetric outlines, a perimeter sealing land, and a substantially coplanar low-relief surface compatible with adhesive wet-out. Materials include suede, synthetic suede, microfiber, and flexible polymer compositions formulated for glide or grip, including non-marking, water-resistant polymers for indoor or outdoor use. User-replaceable sections, kits, and adhesive-based installation methods are also described.

Description

[0001] R2024-105-PCT (GC)

[0002] FOOTWEAR SOLE STRUCTURE WITH REPLACEABLE FRICTION-MODIFYING MATERIAL SECTIONS FOR DANCING

[0003] PRIORITY AND RELATED PATENT APPLICATIONS

[0004] The present application is related to, and claims the priority benefit of, U.S. provisional patent application serial no. 63 / 715,183, filed November 1, 2024, and U.S. provisional patent application serial no. 63 / 708,934, filed October 18, 2024. The contents of each of the aforementioned applications are incorporated herein directly and by reference in their entirety.

[0005] FIELD OF THE INVENTION

[0006] The present disclosure relates to the field of footwear design, and more specifically, to a footwear sole structure featuring replaceable friction-modifying material sections strategically placed in recessed areas of the sole, particularly suited for dancing and performance arts.

[0007] The present disclosure also relates to the field of footwear design, and more specifically, to a footwear sole structure featuring a single shallow recessed area covering a substantial portion of the sole. This structure accommodates a replaceable thin friction-modifying material section, particularly suited for dancing and performance arts.

[0008] The present disclosure further relates to advancements in footwear sole structures, specifically incorporating a sole fabricated using manufacturing techniques, including but not limited to three-dimensional (3D) printing, from flexible materials, which may feature integrated holes within one or more recessed areas. These holes, when present, reduce weight and enhance flexibility and are covered by replaceable friction-modifying material sections. Importantly, the holes may not extend entirely through the sole; they can be internal cavities or extend partially through the sole, covered by subsequent layers during the manufacturing process. The sole may include variations in layer thickness, material composition, or other structural properties in different regions to achieve desired sole characteristics. The frequency and presence of these holes can vary depending on the desired properties, providing customization for dancing and performance arts.

[0009] BACKGROUND

[0010] Dance footwear is designed to provide the optimal balance between grip and slide on various dance floor surfaces. Traditional dance shoes often feature soles made entirely of materials like suede or leather, which are effective for indoor dance environments due to their ideal friction properties. Suede soles provide dancers with the necessary balance of grip and slide required for precise movements. However, using entire soles made of suede significantly increases manufacturing costs due to the material's expense. R2024-105-PCT (GC)

[0011] Moreover, suede soles are susceptible to wear and tear, especially under the rigorous demands of dancing and the performance arts. When suede soles wear out, which can happen relatively quickly, the entire shoe often must be replaced. Professional repairs or resoling are not always feasible and can be costly and inconvenient. As a result, many consumers choose to discard the shoes altogether, leading to greater waste and higher costs.

[0012] Additionally, many dance shoes prioritize function over style, limiting their appeal to dancers who prefer more fashionable options like trainers or sneakers. While some manufacturers produce dance shoes styled as trainers, those with suede soles are rare and often very expensive due to the high cost of materials and specialized manufacturing processes. This limits accessibility for many dancers seeking both performance and style in their footwear. There is a need for a footwear sole design that combines the performance benefits of materials like suede with reduced costs, enhanced durability, and aesthetic versatility.

[0013] Existing dance shoes with polymer-based soles are often designed with fixed friction zones optimized for specific types of dance. Some prior art discloses footwear with integrated low-friction pivot points on the sole to facilitate spinning or pivoting movements. These pivot points are permanently affixed and cannot be replaced or adjusted. When these pivot points wear out, the shoes cannot be professionally repaired due to the integrated nature of the design and the materials used. Consequently, the entire shoe often must be discarded. This leads to limitations such as wear over time, whereby the integrated pivot points cannot be replaced independently, requiring the entire shoe to be discarded once the pivot point wears out, a lack of customization, whereby users cannot adjust the friction levels or positions of the pivot points to suit different dance styles or personal preferences, and limited versatility, whereby fixed designs do not accommodate varying floor surfaces or environmental conditions.

[0014] In view of the same, there is a need for a footwear sole structure that overcomes these limitations by providing replaceable friction-modifying elements that can be easily customized and replaced by the user. Such a design would enhance performance, extend the shoe's lifespan, and offer greater versatility across various dance styles and the performance arts. Additionally, there is a desire for this functionality to be incorporated into more fashionable footwear options without significantly increasing costs. A further need is that the footwear remains wearable with the replaceable elements absent, achieved by maintaining a shallow recess and providing tread features within and around the recess.

[0015] Many social dancers prefer to wear trainers or sneakers that are stylish and align with current fashion trends. While specialized dance trainers are available that incorporate friction-modifying materials, they arc often expensive and, once the soles wear out, the entire shoe must be replaced. R2024-105-PCT (GC)

[0016] This leads to increased costs and inconvenience for dancers. Integrating replaceable frictionmodifying materials into fashionable trainers without altering their appearance presents challenges.

[0017] Flat-soled shoes and those with a gradually contiguous raised heel are popular among dancers for their comfort and aesthetic appeal. Many social dancers prefer dance trainers over traditional dance shoes because trainers offer greater flexibility and comfort without the rigidity of raised heels. However, integrating friction-modifying materials into these designs poses difficulties. Trainers with polymer bases used for dancing, once worn out, cannot be easily replaced, leading to reduced longevity and increased costs for consumers. Similarly, trainers with suede bases are already expensive to purchase, and making the suede replaceable is difficult with traditional manufacturing methods.

[0018] Advancements in manufacturing technologies, such as Computer Numerical Control (CNC) machining, mass production methods, and 3D printing, have made it feasible to produce frictionmodifying material sections separately from the footwear soles with high precision and customization. Computer Numerical Control (CNC) machining and 3D printing allow for on-demand production and the use of specialized materials that may not be practical with traditional manufacturing processes, reducing inventory requirements and costs. These manufacturing techniques also enable additive manufacture of pad articles themselves, including low-friction nonmarking polymer compositions formulated to mimic suede glide, or thicker high-friction grip variants up to about 5.0 millimeters in thickness.

[0019] While prior art discloses footwear with replaceable parts of the sole, these replacements often involve substantial portions of the sole that are integral to the shoe’s structure, potentially altering the shoe's integrity, fit, and performance. In contrast, the present disclosure specifically targets the replacement of a thin friction-modifying material layer adjunct to the sole, within a single shallow recessed area, without replacing or altering any structural components of the sole itself.

[0020] This friction-modifying material layer is only a few millimeters thick and is designed to always protrude above the surrounding sole surface, maintaining a height greater than the surrounding edges of the shoe sole. This ensures consistent friction engagement with the dance floor while preventing premature wear from lateral forces. Keeping the friction-modifying material thin is essential to maintain the flexibility of the shoe, which is crucial for dancers. A thicker material could make the shoe rigid, hindering the fluid movements required in dance performances. In preferred embodiments, the replaceable sections are about 2 millimeters to about 2.5 millimeters thick and protrude by at least about 0.5 millimeter, while grip-oriented sections may be thicker up to about 5.0 millimeters, with protrusion capped at 5.0 millimeters or less. R2024-105-PCT (GC)

[0021] Moreover, the ability to select different types of friction-modifying materials allows customers to choose between indoor and outdoor use at the time of purchase or replace them later. For example, materials like suede or synthetic suede are ideal for indoor dance floors, providing the necessary slide and grip. Alternatively, more durable polymers can be selected for outdoor environments, where surfaces may be rougher. This versatility enhances the shoe's functionality and extends its usability across various settings. In certain embodiments, the polymer sections are water- resistant, maintain low-friction properties even on damp or wet surfaces, and are non-marking to preserve dance floors.

[0022] The present disclosure also offers significant environmental benefits by reducing waste. Instead of discarding entire shoes when the soles wear out, users can simply replace the small frictionmodifying material section. This conserves resources and lowers the environmental impact associated with shoe production and disposal.

[0023] Safety considerations are also addressed. By maintaining consistent friction properties, the shoe enhances traction and stability during dance performances, reducing the risk of slips and falls caused by worn-out soles.

[0024] There is a need for a footwear sole structure that overcomes these limitations by providing a design suitable for flat soles or gradually raised soles, featuring a single shallow recessed area accommodating a replaceable thin friction-modifying material section. Such a design enhances performance, extends the shoe's lifespan, offers greater versatility across various dance styles and performance arts, and provides environmental and safety benefits.

[0025] Advancements in additive manufacturing, such as 3D printing, have opened new possibilities in footwear design, allowing for complex geometries and customized structures not feasible with traditional manufacturing methods. Dancers require footwear that is lightweight and highly flexible to perform intricate movements and maintain agility.

[0026] Traditional soles made from uniform materials often present a trade-off between durability and flexibility. Introducing holes into the sole structure can reduce weight and increase flexibility; however, doing so without compromising structural integrity is challenging. Moreover, soles can be constructed with variations in layer thickness, material composition, or other structural properties throughout different regions to enhance certain characteristics.

[0027] There is a need for a footwear sole structure that leverages manufacturing techniques, including but not limited to 3D printing to create soles with the option to include integrated holes strategically placed anywhere under the friction-modifying material to enhance flexibility and reduce weight while maintaining structural integrity. Importantly, these holes may not extend entirely R2024-105-PCT (GC) through the sole; they can be internal cavities or extend partially through the sole, covered by subsequent layers during the manufacturing process.

[0028] Additionally, the ability to adjust layer thickness, material composition, or other structural properties in different regions allows for further customization of the sole's performance. Covering these holes with replaceable friction-modifying material sections ensures debris protection and allows for customization of friction properties suitable for various dance styles and environments. This flexible design provides further customization based on desired properties.

[0029] In further embodiments, the footwear system enables a refurbishment pathway that extends product life and reduces waste. Because the replaceable friction-modifying sections bear the majority of ground wear, the outsole and recessed areas typically remain within specification while the upper reaches end-of-life. Used footwear can be collected, the upper separated from the sole, the sole inspected and cleaned, and a replacement upper affixed so that the sole is re-used. This approach reduces material consumption relative to full shoe replacement and supports circular reuse.

[0030] BRIEF SUMMARY

[0031] The present disclosure relates to a footwear sole structure for dancing, featuring replaceable friction-modifying material sections in recessed areas of the sole's heel and forefoot portions. These sections protrude from the bottom surface and may, in certain embodiments, vary in height for different friction levels, retaining the performance benefits of materials like suede. They are standardized in shape and size for compatibility across shoe designs, allowing integration into fashionable footwear without significantly increasing costs or altering appearance. Users can maintain optimal shoe performance by replacing worn sections themselves, eliminating the need for replacement or professional repairs. Additionally, consumers can select specific friction-modifying materials at the time of ordering for indoor or outdoor use, enabling personalized customization. The design reduces manufacturing costs by minimizing material usage to key pressure areas, extends shoe lifespan through easy replacement of worn sections, and offers aesthetic versatility. In preferred embodiments, the recessed areas are shallow (at or below about 2 millimeters, typically about 1 millimeter) and the replaceable sections are thin (about 2 millimeters to about 2.5 millimeters) with installed protrusion of at least about 0.5 millimeter, thereby preserving flexibility and configured to maintain ground contact in the region of the replaceable section during stance and pivot motions. In some embodiments, the recessed area depth may be up to about three millimeters, while maintaining sole flexibility and the ability to wear the footwear when the section is absent. The footwear remains wearable with the sections absent by virtue of the shallow recess depth and adjacent tread features. Tread within a recess, where present, is substantially coplanar and optional. R2024-105-PCT (GC)

[0032] The present disclosure also relates to a footwear sole structure featuring a sole with a single shallow recessed area covering a substantial portion of the bottom surface, extending from the forefoot portion to the heel portion. A replaceable thin friction-modifying material section, produced separately from the shoe using advanced manufacturing techniques like CNC machining, mass production methods, and 3D printing, is customized to fit the specific shoe design and is positioned within the recessed area. The material section has a thickness greater than the depth of the recessed area, protruding from the bottom surface by at least 0.5 mm, providing a consistent friction surface. The friction-modifying material section is always proud of the sole's surface and maintains a height greater than the surrounding edges of the shoe sole, ensuring optimal friction engagement while preventing premature wear from lateral forces. Unlike prior art that replaces substantial parts of the sole, this design replaces only a thin friction-modifying material layer adjunct to the sole, preserving the shoe's structural integrity.

[0033] The thinness of the friction-modifying material maintains the flexibility of the shoe, which is essential for dancers to perform fluid movements. The sole remains structurally intact, and its overall strength is unaffected by the shallow recess. The friction-modifying material section is affixed using an adhesive fastening mechanism, avoiding additional depth or complexity in the recess. Adhesive may include pressure-sensitive adhesive (PSA) or PSA transfer film as a preferred attachment to preserve flexibility and enable user replacement. Alternative fastening mechanisms, such as mechanical interlocks, snap-fit connectors, and magnetic fasteners, may also be used where compatible. Users can select different types of friction-modifying materials at the time of purchase or replace them later, choosing materials suitable for indoor use, like suede, or durable polymers for outdoor use. The friction-modifying material can be replaced by users themselves without professional assistance, reducing long-term costs and enhancing convenience. Environmental benefits are realized by reducing waste, as only the small friction-modifying material section needs replacement when worn.

[0034] Consistent friction properties enhance safety by improving traction and stability during use. The design allows dancers to wear fashionable trainers or sneakers they prefer, integrating replaceable friction-modifying materials without compromising aesthetics or incurring high replacement costs. This design extends the footwear's lifespan, enhances performance, and offers aesthetic versatility by integrating functional elements into fashionable footwear without significantly altering appearance. In some embodiments, the recessed area includes a smooth perimeter sealing land to promote adhesive wet-out and inhibit moisture ingress. The sealing land may have a width of about 2 to about 20 millimeters (e.g., about 2-5 mm for youth sizes and about 5-20 mm for adult sizes). An inward low-rclicf, substantially coplanar microtcxturcd field is R2024-105-PCT (GC) provided to improve adhesive interlock. The sealing land and substantially coplanar microtexture (e.g., height < 0.2 mm) are configured for pressure-sensitive adhesive wet-out in a thin-gauge system to reduce peel initiation at the perimeter, enabling use of a shallow recess compatible with pad-absent wearability. Referring to FIG. 15, a sealing land surrounds a substantially coplanar microtextured central field to promote adhesive wet-out and may incidentally assist traction when a section is absent. Pad-absent wearability is achieved by the shallow recess and adjacent tread; microtexture is optional. Sections may include an edge chamfer or bevel at the perimeter to reduce peel initiation and increase local contact pressure over the sealing land. The chamfer is optional and may be favored for additively manufactured or machined sections; other embodiments employ a square edge. Referring to FIG. 16, an edge chamfer positioned over the sealing land reduces peel initiation and increases local contact pressure. For grip-oriented use, sections may be thicker up to about 5.0 millimeters, with protrusion capped at about 5.0, 4.5, or 4.0 millimeters depending on recess depth, and may optionally include micro-lugs or fine siping while remaining a thin replaceable layer distinct from structural outsoles. The recess or section may include indexing indicia or a non-rotationally symmetric outline (e.g., keyed or teardrop geometry) to guide single -placement alignment and resist rotation. In certain embodiments, a refurbishment method includes receiving used footwear with soles of the present disclosure, removing a worn upper, preparing the sole, and affixing a replacement upper so that the sole and replacement sections are re-used, thereby reducing waste.

[0035] The present disclosure also relates to a footwear sole structure fabricated using manufacturing techniques, including but not limited to 3D printing, from flexible materials, with variations in layer thickness, material composition, or other structural properties within different regions to achieve desired characteristics.

[0036] The sole features integrated holes, which may be internal cavities or extend partially through the sole, within one or more recessed areas covered by replaceable friction-modifying material sections. These holes arc strategically placed under the friction-modifying material sections to reduce weight and enhance flexibility without compromising structural integrity. The placement, number, and size of the holes can be adjusted based on desired flexibility and performance characteristics. The 3D manufacturing process enables efficient, on-demand production and customization, reducing manufacturing costs and material waste. This design enhances performance, extends the footwear's lifespan, and offers versatility across various dance styles and performance arts.

[0037] The present disclosure includes disclosure that addresses these needs by introducing a sole structure with replaceable friction-modifying material sections strategically placed only in critical areas of the sole. This design reduces the quantity of expensive materials required and enables standardization of these friction-modifying sections in terms of shape and size. R2024-105-PCT (GC)

[0038] By allowing users to replace worn sections themselves without the need for replacement of the entire shoe or professional repairs, the present disclosure includes disclosure that extends the footwear's lifespan and maintains optimal performance. This not only reduces costs for consumers but also minimizes environmental waste associated with discarding shoes due to sole wear. Furthermore, the present disclosure allows for the integration of these functional elements into fashionable footwear, such as trainers or sneakers, without significantly increasing production costs or altering the shoes' appearance. This aesthetic flexibility expands footwear options for dancers, making high-performance dance footwear more accessible and appealing.

[0039] The present disclosure includes disclosure of a footwear sole structure that combines performance, cost-effectiveness, durability, and aesthetic versatility. The sole features at least two recessed areas formed into its bottom surface - one located in the forefoot portion and one in the heel portion - corresponding to essential pressure points used during dancing. Replaceable frictionmodifying material sections are affixed within these recessed areas and protrude slightly from the bottom surface of the sole. In preferred embodiments, the recessed areas are shallow (at or below about 2 millimeters, typically about 1 millimeter), and the sections are thin (about 2 to about 2.5 millimeters) with installed protrusion of at least about 0.5 millimeter.

[0040] By strategically placing friction-modifying materials, such as suede or synthetic alternatives, only in critical contact areas, the present disclosure reduces the amount of expensive material required, thereby lowering manufacturing costs. The standardized shapes and sizes of these sections allow manufacturers to use uniform components across different footwear sizes and designs, simplifying production processes and reducing expenses. Sections may be manufactured by additive manufacturing, cutting from molded or extruded sheet, or CNC-machining from sheet stock; polymer compositions may be non-marking and formulated to mimic suede glide or to provide higher grip, including on damp or wet surfaces.

[0041] The replaceable nature of the friction-modifying sections allows users to maintain their shoes in optimal condition without the need for replacement or professional repairs. Worn sections can be easily replaced by the user, extending the footwear's lifespan and ensuring consistent performance. This approach reduces costs and promotes sustainability by minimizing waste.

[0042] Users can customize the friction levels by selecting different materials and, in certain embodiments, adjusting the protrusion heights of the sections, tailoring the shoes to their specific needs and preferences. This customization enhances performance by providing an optimal balance of grip and slide across various dance styles and performance arts. Tread elements adjacent to the recess and, where present within the recess, substantially coplanar with the recess floor, provide ground contact when a section is absent and arc compatible with adhesive bonding. In other R2024-105-PCT (GC) embodiments the recess floor is smooth and free of tread; pad-absent wearability is maintained by the shallow recess depth and adjacent tread.

[0043] The present disclosure also allows the functional elements to be incorporated into the soles of fashionable footwear, such as trainers or sneakers, without significantly increasing production costs or altering their appearance. This enables the production of cost-effective, stylish dance footwear that retains the performance benefits of traditional dance shoes, expanding footwear options for dancers.

[0044] Consumers can select specific friction-modifying material sections at the time of ordering the shoes. For indoor use, materials like suede or synthetic suede provide optimal slide and grip on dance floors. For outdoor use, more durable polymers can be selected to withstand rougher surfaces while maintaining the desired friction properties. This selection process allows users to tailor their footwear to their specific performance environments.

[0045] The friction-modifying material sections can be produced using advanced manufacturing techniques, including Computer Numerical Control (CNC) machining, mass production methods, and 3D printing. Computer Numerical Control (CNC) machining and 3D printing methods enable high precision, on-demand customization, and the use of specialized materials that may not be feasible with traditional manufacturing processes. Utilizing these techniques, manufacturers can efficiently produce components with complex geometries, reduce inventory requirements, and respond quickly to specific customer needs. Sections are affixed using adhesive, including PSA or PSA transfer film; alternative fastening mechanisms such as mechanical interlocks, snap-fit connectors, and magnetic fasteners may also be used.

[0046] In at least one embodiment of a footwear sole structure of the present disclosure, said footwear sole structure comprises a sole including a heel portion and a forefoot portion and defining a bottom surface, and at least two recessed areas defined within the bottom surface of the sole, with at least one recessed area of the at least two recessed areas located in the forefoot portion and at least one recessed area of the at least two recessed areas located in the heel portion, wherein the at least two recessed areas are configured to receive a replaceable friction-modifying material section therein.

[0047] Tn at least one embodiment of a footwear sole structure of the present disclosure, said footwear sole structure further comprises at least two replaceable friction-modifying material sections, each replaceable friction-modifying material section of the at least two replaceable friction-modifying material sections positioned in each recessed area of the at least two recessed areas.

[0048] In at least one embodiment of a footwear sole structure of the present disclosure, each recessed area provides a substantially smooth or planar adhesion surface at a floor thereof, the adhesion surface being configured to promote adhesive wet-out and secure bonding of a friction- R2024-105-PCT (GC) modifying material section affixed therein by a pressure-sensitive adhesive, a pressure-sensitive adhesive transfer film, or another adhesive fastening mechanism, and wherein adhesion surfaces within the recessed areas are structurally and functionally distinct from textured tread surfaces of the surrounding bottom surface that are configured to provide traction and ground contact when at least one replaceable section is absent.

[0049] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material sections have a thickness greater than a depth of the corresponding recessed areas such that the sections protrude beyond adjacent outsole surfaces, and wherein the recessed areas are positioned at weight-bearing locations such that ground contact during normal use occurs primarily through external surfaces of the friction-modifying material sections, thereby concentrating wear on the replaceable sections and protecting an underlying sole structure.

[0050] In at least one embodiment of a footwear sole structure of the present disclosure, the recessed areas correspond to the forefoot portion and the heel portion of the sole.

[0051] In at least one embodiment of a footwear sole structure of the present disclosure, each replaceable friction-modifying material section protrudes from the bottom surface of the sole.

[0052] In at least one embodiment of a footwear sole structure of the present disclosure, each replaceable friction-modifying material section has a friction property different from a friction property of the sole.

[0053] In at least one embodiment of a footwear sole structure of the present disclosure, each frictionmodifying material section is standardized in geometric shape and size to allow compatibility with multiple shoe sizes and designs.

[0054] In at least one embodiment of a footwear sole structure of the present disclosure, each frictionmodifying material section protrudes from the bottom surface of the sole by at least 0.5 mm. In some embodiments, protrusion is capped at about 5.0 millimeters, optionally at about 4.5 or about 4.0 millimeters depending on recess depth.

[0055] In at least one embodiment of a footwear sole structure of the present disclosure, each frictionmodifying material section protrudes from the bottom surface of the sole at varying heights to provide different friction levels in different areas of the sole.

[0056] In at least one embodiment of a footwear sole structure of the present disclosure, the at least two friction-modifying material sections are made from a material selected from the group consisting of suede, synthetic suede, microfiber, and synthetic polymers. Synthetic polymers may be nonmarking and water-resistant, maintaining low-friction properties on damp or wet surfaces. R2024-105-PCT (GC)

[0057] In at least one embodiment of a footwear sole structure of the present disclosure, the at least two friction-modifying material sections are made from a material selected from the group consisting of suede, synthetic suede, and microfiber, wherein the material is selected for indoor use.

[0058] In at least one embodiment of a footwear sole structure of the present disclosure, the at least two friction-modifying material sections are made from a synthetic material configured for outdoor use.

[0059] In at least one embodiment of a footwear sole structure of the present disclosure, the at least two recessed areas and the at least two replaceable friction-modifying material sections are configured in geometric shapes selected from the group consisting of circles, ovals, and crescents. Non-rotationally symmetric outlines (e.g., keyed or teardrop) may be used to resist rotation and to guide single -placement alignment.

[0060] In at least one embodiment of a footwear sole structure of the present disclosure, the sole structure further comprises a fastening mechanism configured to fasten each replaceable frictionmodifying material section within each recessed area.

[0061] In at least one embodiment of a footwear sole structure of the present disclosure, the fastening mechanisms are selected from the group consisting of adhesives, mechanical interlocks, snap-fit connectors, and magnetic fasteners, thereby permitting removal and replacement of each replaceable friction-modifying material section. Adhesive, including PSA or PSA transfer film, is preferred to preserve flexibility and reduce recess complexity.

[0062] In at least one embodiment of a footwear sole structure of the present disclosure, the footwear sole structure is formed as part of a shoe.

[0063] In at least one embodiment of a footwear sole structure of the present disclosure, wherein the sole defines a cutout in a front toe area of the sole, the cutout shaped as a crescent or other suitable geometry and positioned to align with the replaceable friction-modifying material section within the at least one recessed area located in the forefoot portion, enhancing flexibility and ensuring optimal alignment for spinning or pivoting movements performed on a ball of a foot using the footwear sole structure.

[0064] In at least one embodiment of a footwear sole structure of the present disclosure, the footwear sole structure further comprises one or more additional recessed areas defined within the bottom surface of the sole, and one or more additional replaceable friction-modifying material sections each positioned within each recessed area of the one or more additional recessed areas.

[0065] In at least one embodiment of a footwear sole structure of the present disclosure, the one or more additional replaceable friction-modifying material sections each protrude from the bottom R2024-105-PCT (GC) surface of the sole at varying heights to allow for customization of friction levels tailored to specific dance styles or environments.

[0066] In at least one embodiment of a footwear sole structure of the present disclosure, the sole is selected from the group consisting of a flat sole design with a continuous bottom surface, a split sole design, and a raised heel design.

[0067] In at least one embodiment of a footwear sole structure of the present disclosure, each replaceable friction-modifying material section is produced using manufacturing techniques that enable on-demand customization and that reduce inventory requirements.

[0068] In at least one embodiment of a footwear sole structure of the present disclosure, the manufacturing techniques are selected from the group consisting of Computer Numerical Control (CNC) machining and 3D printing.

[0069] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the method comprises forming a sole including a heel portion and a forefoot portion, creating at least two recessed areas into the bottom surface of the sole at the heel portion and the forefoot portion, and positioning a replaceable friction-modifying material section shaped to fit within each recessed area of the at least two recessed areas, wherein replaceable friction-modifying material sections protrude from a bottom surface of the sole. The recessed areas may be shallow (at or below about 2 millimeters, typically about 1 millimeter) with sections of about 2 to about 2.5 millimeters thickness.

[0070] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the creating step further comprises creating a cutout in a front toe area of the sole shaped as a crescent or other suitable geometry to align with the replaceable friction-modifying material section at the forefoot portion.

[0071] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the method further comprises the step of affixing the replaceable frictionmodifying material sections within the recessed areas using a fastening mechanism selected from the group consisting of adhesives, mechanical interlocks, snap-fit connectors, and magnetic fasteners.

[0072] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the method further comprises the steps of standardizing the replaceable frictionmodifying material sections in geometric shape and size to allow compatibility with multiple shoe sizes and designs, selecting the replaceable friction-modifying material sections from materials suitable for indoor or outdoor use, and producing the friction-modifying material sections using manufacturing techniques that enable on-demand customization, the techniques including Computer R2024-105-PCT (GC)

[0073] Numerical Control (CNC) machining and 3D printing, wherein said steps occur prior to the step of positioning the replaceable friction-modifying material sections.

[0074] In at least one embodiment of a footwear sole structure of the present disclosure, the footwear sole structure comprises a sole including a heel portion and a forefoot portion and defining a bottom surface, a single shallow recessed area formed within the bottom surface of the sole, extending across a substantial portion of the sole between the forefoot portion to the heel portion, and a replaceable thin friction-modifying material section positioned within the single shallow recessed area, the friction-modifying material section having a thickness greater than the depth of the recessed area such that it protrudes from the bottom surface of the sole, wherein the friction-modifying material section is affixed within the recessed area using an adhesive fastening mechanism, and wherein the friction-modifying material section is adjacent to the sole and does not replace or alter any structural components of the sole. Adhesive may include PSA or PSA transfer film.

[0075] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section protrudes from the bottom surface of the sole by at least 0.5 mm. Protrusion may be capped at about 5.0 millimeters, optionally about 4.5 or about 4.0 millinielcrs.

[0076] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section protrudes by no more than 4 mm from the bottom surface of the sole.

[0077] In at least one embodiment of a footwear sole structure of the present disclosure, the single shallow recessed area has a depth of no more than 2 mm, wherein the depth is about 1 millimeter.

[0078] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section is made from a material selected from the group consisting of suede, synthetic suede, microfiber, and synthetic polymers. Polymeric sections may be non-marking and maintain low-friction even on damp or wet surfaces.

[0079] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section has friction properties different from that of the sole.

[0080] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section always extends beyond the bottom surface of the sole and maintains a height greater than surrounding edges of the sole.

[0081] In at least one embodiment of a footwear sole structure of the present disclosure, the sole is selected from the group consisting of a flat sole design with a continuous bottom surface and a gradually raised sole design without a separate independently raised heel.

[0082] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section is produced separately from a shoe it is coupled to using manufacturing techniques. R2024-105-PCT (GC)

[0083] In at least one embodiment of a footwear sole structure of the present disclosure, the manufacturing techniques are selected from the group consisting of Computer Numerical Control (CNC) machining and 3D printing.

[0084] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section is replaceable with different materials to adapt the footwear for indoor or outdoor use, allowing a user to select or switch between materials such as suede for indoor environments and polymers for outdoor environments.

[0085] In at least one embodiment of a footwear sole structure of the present disclosure, the frictionmodifying material section can be replaced by a user without professional assistance.

[0086] In at least one embodiment of a footwear sole structure of the present disclosure, the use of the adhesive fastening mechanism as an exclusive fastening mechanism maintains the flexibility of the sole.

[0087] In at least one embodiment of a footwear sole structure of the present disclosure, the footwear sole structure reduces waste by allowing only the friction-modifying material section to be replaced when worn.

[0088] In at least one embodiment of a footwear sole structure of the present disclosure, consistent friction properties provided by the friction-modifying material section enhance traction and stability, thereby improving safety during use.

[0089] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the method comprises forming a sole including a heel portion and a forefoot portion and defining a bottom surface, defining a single shallow recessed area within the bottom surface of the sole, extending across a substantial portion of the sole between the forefoot portion to the heel portion, producing a thin friction-modifying material section separately from the sole using manufacturing techniques selected from Computer Numerical Control (CNC) machining, mass production methods, and 3D printing, and affixing the thin friction-modifying material section within the single shallow recessed area using an adhesive fastening mechanism, wherein the frictionmodifying material section protrudes from the bottom surface by at least 0.5 mm and maintains the flexibility of the sole.

[0090] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the friction-modifying material section is made from a material selected from the group consisting of suede, synthetic suede, microfiber, and synthetic polymers, and is customizable for indoor or outdoor use.

[0091] In at least one embodiment of a footwear sole structure of the present disclosure, the footwear sole structure comprises a sole fabricated using manufacturing techniques, including but not limited R2024-105-PCT (GC) to 3D printing and mass production methods from one or more flexible materials, with variations in layer thickness, material composition, or other structural properties within different regions to achieve desired sole characteristics, one or more recessed areas defined within a bottom surface of the sole, replaceable friction-modifying material sections positioned within the one or more recessed areas, wherein the sole includes a plurality of holes defined within the sole, whereby the holes, when present are strategically placed to reduce the weight of the sole and enhance flexibility, may be internal cavities or extend partially or entirely through a thickness of the sole in areas beneath the one or more recessed areas, do not compromise a structural integrity of the sole, and are covered by the replaceable friction-modifying material sections when they extend to the bottom surface to prevent ingress of debris, wherein the placement, number, and size of the holes, when present, are adjustable based on desired flexibility and performance characteristics, and wherein the holes are located anywhere under the replaceable friction-modifying material sections, potentially covering substantially the entire sole.

[0092] In at least one embodiment of a footwear sole structure of the present disclosure, the replaceable friction-modifying material sections cover substantially the bottom surface of the sole in its entirety.

[0093] In at least one embodiment of a footwear sole structure of the present disclosure, the plurality of holes are specifically positioned within one or more regions selected from the group consisting of a heel portion, a midfoot portion, a forefoot portion, a ball portion, and a toe area of the sole, to provide targeted flexibility and weight reduction in those areas, and may be internal cavities or extend partially or entirely through the sole.

[0094] In at least one embodiment of a footwear sole structure of the present disclosure, the sole maintains structural integrity and durability during use, regardless of whether the plurality of holes are present, and despite the inclusion of variable construction.

[0095] In at least one embodiment of a footwear sole structure of the present disclosure, wherein the sole is fabricated using a 3D printing technique selected from the group consisting of selective laser sintering, fused deposition modeling, and multi-material printing processes.

[0096] In at least one embodiment of a footwear sole structure of the present disclosure, the flexible materials comprise one or more materials selected from the group consisting of thermoplastic polyurethane, ethylene- vinyl acetate, polyurethane, and combinations thereof.

[0097] In at least one embodiment of a footwear sole structure of the present disclosure, the footwear sole structure further comprises fastening mechanisms configured to secure the replaceable frictionmodifying material sections within the recessed areas, the fastening mechanisms selected from the group consisting of adhesives, mechanical interlocks, snap-fit connectors, and magnetic fasteners. R2024-105-PCT (GC)

[0098] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the method comprises fabricating a sole using manufacturing techniques, including but not limited to 3D printing, from one or more flexible materials, with variations in layer thickness, material composition, or other structural properties within different regions to achieve desired sole characteristics, defining one or more recessed areas in a bottom surface of the sole, optionally integrating a plurality of holes into the sole beneath the recessed areas, wherein the holes, when present, are strategically placed to reduce weight and enhance flexibility without compromising structural integrity, and may be internal cavities or extend partially or entirely through the sole, and positioning replaceable friction-modifying material sections within the recessed areas, the frictionmodifying material sections covering the plurality of holes, when present, to prevent ingress of debris.

[0099] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the placement, number, and size of the plurality of holes, when present, are adjusted based on desired flexibility and performance characteristics, and the holes are located anywhere under the replaceable friction-modifying material sections, potentially covering substantially an entirety of the sole.

[0100] In at least one embodiment of a method of manufacturing a footwear sole structure of the present disclosure, the plurality of holes are specifically positioned within one or more regions selected from the group consisting of a heel portion, a midfoot portion, a forefoot portion, a ball portion, and a toe area of the sole, to provide targeted flexibility and weight reduction in those areas.

[0101] In at least one embodiment of a footwear sole structure of the present disclosure, a recessed area has a depth of about 2 millimeters or less, typically about 1 millimeter; in some embodiments, the depth is up to about 3 millimeters while maintaining sole flexibility and wearability when a section is absent.

[0102] In at least one embodiment of a footwear sole structure of the present disclosure, a replaceable thin section has a thickness of about 2 to about 2.5 millimelers and, when installed, protrudes by at least about 0.5 millimeter beyond adjacent outsole surfaces.

[0103] In at least one embodiment, the protrusion is configured to maintain ground contact in the region of the replaceable section during stance and pivot motions.

[0104] In at least one embodiment, a recessed area includes a smooth perimeter sealing land surrounding a substantially coplanar low-relief microtextured field configured to promote adhesive wet-out; the sealing land may have a width of about 2-20 millimeters and the microtexture a height of not more than about 0.2 millimeter. R2024-105-PCT (GC)

[0105] In at least one embodiment, at least one of a recess or replaceable section includes indexing indicia or a non-rotationally symmetric outline (e.g., keyed or teardrop) to guide single-placement alignment and resist rotation.

[0106] In at least one embodiment, a replaceable section includes an edge chamfer or bevel positioned over the sealing land to reduce peel initiation and increase local contact pressure.

[0107] In at least one embodiment, kits and methods are provided for replacement and refurbishment, including instructions and at least one of a surface-preparation wipe, primer, or adhesive, with indexing guidance for placement.

[0108] BRIEF DESCRIPTION OF THE DRAWINGS

[0109] The disclosed embodiments and other features, advantages, and disclosures contained herein, and the matter of attaining them, will become apparent and the present disclosure will be better understood by reference to the following description of various exemplary embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein:

[0110] FIG. 1A shows a top view of the footwear sole structure including the heel portion and forefoot portion with recessed areas, according to at least one embodiment of the present disclosure.

[0111] FIG. IB shows a side view of footwear (a shoe) having an independently-raised heel design, according to at least one embodiment of the present disclosure.

[0112] FIG. 1C shows a side view of footwear (a shoe) having a gradually raised and contiguous raised heel design, according to at least one embodiment of the present disclosure.

[0113] FIG. ID shows a side view of footwear (a shoe) having a split sole design, according to at least one embodiment of the present disclosure.

[0114] FIG. 2 shows a cross-sectional view of the sole, depicting the recessed areas and the replaceable friction-modifying material sections protruding from the bottom surface of the sole, according to at least one embodiment of the present disclosure.

[0115] FIG. 3 shows a top view of the footwear sole, illustrating the geometric shapes of the recessed areas in the forefoot and heel portions, including the front toe cutout aligned with the frictionmodifying section under the ball of the foot, according to at least one embodiment of the present disclosure.

[0116] FIG. 4 shows a top view of the fastening mechanisms used to affix the friction-modifying material sections within the recessed areas of the sole, according to at least one embodiment of the present disclosure. R2024-105-PCT (GC)

[0117] FIG. 5 shows various standardized shapes and sizes of the friction-modifying material sections, demonstrating compatibility with different shoe sizes and designs, according to at least one embodiment of the present disclosure.

[0118] FIG. 6 shows an exploded view of the footwear sole, illustrating the assembly process of the replaceable friction-modifying material sections into the recessed areas, according to at least one embodiment of the present disclosure.

[0119] FIG. 7 shows alternative embodiments of the footwear sole structure, highlighting the multiple predetermined geometrical recessed areas tailorable for multiple dance styles, including raised heel designs and flat sole designs, according to at least one embodiment of the present disclosure.

[0120] FIG. 8 illustrates an embodiment of a sole structure with friction-modifying material sections protruding at varying heights to provide different friction levels in different areas of the sole, according to at least one embodiment of the present disclosure.

[0121] FIG. 9A shows a top view of a footwear sole structure including a heel portion and a forefoot portion with a single shallow recessed area covering a substantial portion of the sole, according to at least one embodiment of the present disclosure.

[0122] FIG. 9B shows a side view of footwear (a shoe) having a flat sole design with a single shallow recessed area, according to at least one embodiment of the present disclosure.

[0123] FIG. 9C shows a side view of footwear (a shoe) having a gradually raised sole design without a separate independently raised heel, featuring a single shallow recessed area, according to at least one embodiment of the present disclosure.

[0124] FIG. 10 shows a cross-sectional view of the sole, depicting a single shallow recessed area and a replaceable thin friction-modifying material section protruding from the bottom surface of the sole, according to at least one embodiment of the present disclosure.

[0125] FIG. 11 shows an exploded view of the footwear sole, illustrating the assembly process of a replaceable thin friction-modifying material section into a single shallow recessed area using an adhesive fastening mechanism, according to at least one embodiment of the present disclosure.

[0126] FIG. 12A illustrates a top view of a footwear sole structure, showing the sole with multiple recessed areas and integrated holes distributed throughout various portions of the sole, whereby the holes may be internal cavities or extend partially through the sole, according to at least one embodiment of the present disclosure.

[0127] FIG. 12B depicts a cross-sectional view of the sole, showing the replaceable frictionmodifying material sections positioned within the recessed areas, wherein the upper shoe material is indicated by dashed lines to be affixed to the sole, and wherein integrated holes arc not visible in this R2024-105-PCT (GC) figure, as they may be internal or covered by layers of the sole, according to at least one embodiment of the present disclosure.

[0128] FIG. 12C presents a cross-sectional view of the sole, showing an additional middle layer of different material sandwiched between the top and bottom layers of the sole, whereby the middle layer alters the sole's properties, such as flexibility, cushioning, or stiffness, by introducing a material with different characteristics, wherein replaceable friction-modifying material sections are positioned within the recessed areas, wherein upper shoe material is indicated by dotted lines, and wherein integrated holes may be located within any of the layers and may not extend through the entire thickness of the sole, according to at least one embodiment of the present disclosure.

[0129] FIG. 13 provides an exploded view of the footwear sole, illustrating the bottom surface with recessed areas and integrated holes, wherein the holes may be internal or partially extending through the sole, wherein the assembly process of positioning the replaceable friction-modifying material sections over the recessed areas is depicted, showing how the sections cover the holes and are affixed within the recessed areas, and wherein fastening mechanisms are not shown in this figure, according to at least one embodiment of the present disclosure.

[0130] FIG. 14 illustrates an embodiment of a replaceable section and corresponding recessed area having a non-rotationally symmetric outline, such as a keyed or teardrop geometry, to resist rotation during use, according to at least one embodiment of the present disclosure.

[0131] FIG. 15 illustrates an embodiment of a recessed area including a smooth perimeter sealing land and an inward, substantially coplanar microtextured field to promote adhesive wet-out and optionally provide supplemental traction when a section is absent, according to at least one embodiment of the present disclosure.

[0132] FIG. 16 shows a sectional edge detail of a replaceable section with an edge chamfer or bevel positioned over the sealing land, reducing peel initiation and increasing local contact pressure, according to at least one embodiment of the present disclosure. The chamfer is optional and may be favored for additively manufactured or machined sections; other embodiments employ a square edge, according to at least one embodiment of the present disclosure.

[0133] FIG. 17 illustrates a replaceable section positioned above a recessed area, showing how a registration / indexing guide aligns the section for one-time fit within the recess, according to at least one embodiment of the present disclosure.

[0134] As such, an overview of the features, functions and / or configurations of the components depicted in the various figures will now be presented. It should be appreciated that not all of the features of the components of the figures are necessarily described and some of these non-discussed features (as well as discussed features) arc inherent from the figures themselves. Other non-discussed R2024-105-PCT (GC) features may be inherent in component geometry and / or configuration. Furthermore, wherever feasible and convenient, like reference numerals are used in the figures and the description to refer to the same or like parts or steps. The figures are in a simplified form and not to precise scale.

[0135] DETAILED DESCRIPTION

[0136] For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended.

[0137] Referring to FIG. 1A, an exemplary footwear sole structure 100 of an exemplary shoe 50 of the present disclosure comprises a sole 110 including a heel portion 120 and a forefoot portion 130. The sole 110 may be configured in various designs, including a flat sole design, a raised heel design, or a split-sole design. An exemplary flat sole design of a sole structure 100 of the present disclosure may comprise a continuous, un-elev ated bottom surface extending from the heel portion 120 to the forefoot portion 130, such as shown in FIG. 1 A. An exemplary raised heel design of a sole structure 100 of the present disclosure may include a design whereby the heel portion 120 is elevated relative to the forefoot portion 130, which may be either independently raised, such as shown in FIG. IB, creating a distinct elevation typically found in ballroom or Latin dance shoes, or being gradually raised and contiguous, such as shown in FIG. 1C, featuring a gradual elevation in a continuous manner, as preferred in other dance styles. An exemplary split sole design of a sole structure 100 of the present disclosure, such as shown in FIG. ID, may include a design whereby the heel portion 120 and the forefoot portion 130 are discrete and connected by the footwear upper 180, enhancing flexibility and allowing for greater foot articulation.

[0138] An exemplary sole 110 of the present disclosure includes at least two recessed areas 140 defined within a bottom surface 115 of the sole 110, with at least one recessed area 140 located in the forefoot portion 130 and with at least one recessed area 140 located in the heel portion 120, such as shown in FIG. 4. These recessed areas 140 correspond to the primary pressure points of the foot during dancing, ensuring optimal performance. A midfoot region between the forefoot and heel recessed areas can comprise a ground-contacting tread region configured to provide baseline traction and maintain wearability when the replaceable sections are absent. In preferred embodiments, the recessed areas are shallow (at or below about 2 millimeters, typically about 1 millimeter) to preserve flexibility. In at least one embodiment, multiple replaceable sections collectively cover substantially the bottom surface of the sole. R2024-105-PCT (GC)

[0139] The recessed areas 140 can be configured to provide substantially smooth, planar, or low- texture adhesion surfaces at their floors. These adhesion surfaces are specifically engineered and dimensioned to promote uniform adhesive wet-out and secure bonding of the friction-modifying material sections 150 when affixed therein via pressure-sensitive adhesive, pressure-sensitive adhesive transfer film, or other adhesive fastening mechanisms. The adhesion surfaces within the recessed areas 140 are structurally and functionally distinct from the textured tread surfaces 115 provided on the surrounding bottom surface of the sole 110. The textured tread surfaces 115 may include raised tread elements, grooves, channels, or other surface contours designed to provide traction and ground contact when the friction-modifying material sections 150 are absent or removed, thereby maintaining safe wearability during periods between replacing worn sections with new sections. Such textured surfaces, however, would present non-uniform and inconsistent bonding interfaces if used directly for adhesive attachment, highlighting the advantage of the engineered adhesion surfaces provided within the recessed areas 140.

[0140] As shown in FIG. 2, replaceable friction-modifying material sections 150 can be affixed within each recessed area 140. These sections 150 have friction properties different from the surrounding sole material, providing the necessary balance of grip and slide on dance floors. For example, in high- energy dance formats (e.g., Zumba), a lower-friction forefoot section paired with a higher-friction heel section in the two recessed areas can facilitate rapid turns with controlled stops. The frictionmodifying material sections 150 protrude from the bottom surface 115 due to their thickness. Sections may be about 2 to about 2.5 millimeters thick, protruding by at least about 0.5 millimeter above adjacent outsole surfaces.

[0141] The replaceable nature of these sections 150 allows users to easily remove and replace them when they become worn or when different friction levels are desired. Because the friction-modifying material sections 150 have a thickness greater than the depth of the recessed areas 140 such that the sections 150 protrude beyond the bottom surface 115 of the sole 110 by at least about 0.5 millimeter when installed, and because the recessed areas 140 are strategically positioned at primary groundcontact locations corresponding to the heel portion 120 and forefoot portion 130 where weightbearing pressure is concentrated during stance, walking, and dance movements, ground contact during normal use occurs primarily, or substantially exclusively, through the external surfaces of the friction-modifying material sections 150 rather than through the surrounding portions of the bottom surface 115 of the sole 110 or through the floors of the recessed areas 140 themselves. In this configuration, the majority of wear and abrasion forces are concentrated on the replaceable frictionmodifying material sections 150, while the underlying permanent sole structure 110 is protected from direct wear and ground contact, thereby extending the service life of the sole and reducing the R2024-105-PCT (GC) frequency with which the entire shoe must be replaced. This feature extends the lifespan of the footwear (shoes 50) and provides adaptability across various dance styles and performance arts. Users can maintain their shoes 50 in optimal condition without the need for replacement of the entire shoe 50 or professional repairs, reducing costs and inconvenience. The footwear remains wearable with the sections absent due to the shallow recess and adjacent tread features: any tread within a recess is optional and, if present, is substantially coplanar. The edges of the friction-modifying material sections are protected by the surrounding sole material within the recessed areas, reducing wear on the edges and securing the material in place.

[0142] As shown in FIG. 3, the top view of the sole 110 (the bottom view of the shoe 50) illustrates that the recessed areas 140 can have various geometric shapes, such as circles, ovals, crescents, or other patterns / shapes, depending on the specific pressure points under the forefoot and heel portions. A cutout 170 in the front toe area of the forefoot portion 130 is designed to align with the frictionmodifying material section 150 covering the ball of the foot. This ensures optimal friction properties where they are most needed.

[0143] Referring to FIG. 4, the friction-modifying material sections 150 are affixed within the recessed areas 140 using various fastening mechanisms 155. Adhesives (an exemplary fastening mechanism 155 of the present disclosure) are a primary method due to their reliability, ease of use, and cost-effectiveness. Adhesive may include a pressure-sensitive adhesive (PSA) or PSA transfer film, which preserves flexibility and enables user replacement. Alternative fastening mechanisms 155 include mechanical interlocks, snap-fit connectors, and magnetic fasteners. In adhesive embodiments, the adhesive may be carried on the section and / or disposed on the recess floor (e.g., transfer film); the diagrammatic placement in the figures is not limiting. Each fastening mechanism 155 offers unique advantages and may be selected based on factors such as material section 150 compatibility, manufacturing preferences, desired ease of replacement, and performance requirements during dance movements.

[0144] As depicted in FIG. 5, the friction-modifying material sections 150 can be standardized in geometric shape and size, allowing compatibility with multiple shoe 50 sizes and designs. This standardization simplifies the manufacturing process by reducing the need for shoe-specific components and allows for easy replacement of worn material sections 150 by consumers. Sections and recesses may incorporate indexing indicia or non-rotationally symmetric outlines (e.g., keyed or teardrop shapes) to guide one-time alignment and resist rotation. Referring to FIG. 17, a registration / indexing guide 142 on the section 150 and the recessed area 140 cooperates to align the section for one-time placement within the recess. Pressure-sensitive adhesives used herein are typically intended for single-placement alignment; limited rcpositionablc systems may be used in R2024-105-PCT (GC) some embodiments, but indexing is preferred to aid first-time placement. Referring to FIG. 14, an exemplary non-rotationally symmetric keyed outline 146 resists rotation and guides single-placement alignment.

[0145] FIG. 6 shows an exploded view of the footwear sole 100, illustrating the assembly process of the replaceable friction-modifying material sections 150 into the recessed areas 140.

[0146] FIG. 7 illustrates alternative embodiments of the footwear sole structure 100, identifying the multiple predetermined geometrical recessed areas 140 tailorable for multiple dance styles, including raised heel designs and flat sole designs as referenced herein. Additional recessed areas 140, such as areas 190, can be crescent or other shaped, and can be located at the toe-end and the heel-end of the sole 110.

[0147] In certain embodiments, such as depicted in FIG. 8, the friction-modifying material sections 150 may protrude from the bottom surface 115 of the sole 110 at varying heights to provide different friction levels in different areas of the sole 110. This variation allows different sections to engage with the dance floor under specific conditions, offering customizable friction control to the dancer. For example, in the heel portion 120, a high-friction section 151 of friction-modifying material may comprise a high-friction polymer, protruding a relatively small amount, such as at or about 0.5 mm from the bottom surface 115, and a low-friction section 152 of friction-modifying material may comprise suede, protruding a larger amount, such as at or about 2.5 mm from the bottom surface 115. In such an embodiment, and during standard movements, the low-friction section 152 contacts the floor, facilitating smooth spins and pivots, and by adjusting foot pressure or angle, the high-friction section 151 engages the floor, providing increased grip for controlled stops or directional changes. Such a design enables dancers to modulate friction dynamically in specific embodiments, adapting to various dance movements and ensuring both smooth transitions and secure stops. Sections may range up to about 5.0 millimeters thick for grip-oriented use, with protrusion capped at about 5.0, 4.5, or 4.0 millimeters, and may optionally include micro-lugs or fine siping. Such grip-oriented sections remain thin, replaceable layers distinct from structural outsoles, and footwear remains wearable in their absence due to the shallow recess and adjacent tread.

[0148] In various embodiments, the recessed areas 140 are 0.5 mm or 1.0 mm deep (or somewhere in between), and the friction-modifying material sections 150 are greater than 1.0 mm thick, such as at or between 1.0 mm and 3.5 mm, such that the friction-modifying material sections 150 protrude from the recessed areas 140 by about up to 2.5 mm. In the absence of a section, the shallow recess and surrounding tread features provide baseline traction and maintain safe wearability for ordinary walking. In some embodiments, a recessed area may be up to about 3 millimeters deep while preserving overall flexibility and pad-absent wearability. Preferred embodiments specify recess depth R2024-105-PCT (GC) at or below about 2 millimeters, section thickness of about 2 to about 2.5 millimeters, and protrusion of at least about 0.5 millimeter.

[0149] Referring to FIG. 9A, an exemplary footwear sole structure 200 of an exemplary shoe 50 of the present disclosure comprises a sole 210 including a heel portion 220 and a forefoot portion 230. fhe sole 210 is configured either as a flat sole or as a gradually raised sole without a separate, independently raised heel.

[0150] An exemplary flat sole design, as shown in FIG. 9B, may comprise a continuous, un-elevated bottom surface extending from the heel portion 220 to the forefoot portion 230. An exemplary gradually raised sole design, depicted in FIG. 9C, includes a gradual elevation from the forefoot portion 230 to the heel portion 220, providing heel lift preferred in certain dance styles without a distinct separation between heel and forefoot.

[0151] The sole 210, in at least some embodiments, includes a single shallow recessed area 240 defined within its bottom surface 215, covering a substantial portion of the sole 210. This recessed area 240 extends from the forefoot portion 230 to the heel portion 220, corresponding to the primary contact areas of the foot during dancing, ensuring optimal performance. The recessed area 240 has a depth sufficient to accommodate the thin friction-modifying material while allowing it to protrude above the bottom surface 215. In preferred embodiments, the depth of the recessed area is at or below about 2 millimeters, typically about 1 millimeter. It can be customized in shape to fit the specific design of the shoe 50, made possible by advanced manufacturing techniques.

[0152] As shown in FIG. 10, a replaceable thin friction-modifying material section 250 can be affixed within the single shallow recessed area 240. The friction-modifying material section 250 has a thickness greater than the depth of the recessed area 240, so that it protrudes from the bottom surface 215 by at least 0.5 mm, ensuring consistent friction engagement with the dance floor while preventing the material from being worn down by lateral forces. Section thickness may be about 2 to about 2.5 millimeters for glide-oriented use, with grip-oriented variants thicker up to about 5.0 millimeters. Installed protrusion may be capped at about 5.0, 4.5, or 4.0 millimeters.

[0153] The thinness of the friction-modifying material section 250 is essential to maintain the flexibility of the shoe. Dance shoes require flexibility to accommodate the dynamic movements and foot articulations involved in dancing. A thicker friction-modifying material could introduce rigidity to the sole, hindering the dancer’s performance. By keeping the friction-modifying material thin, the sole remains pliable and responsive, allowing for natural movement and better control.

[0154] Versatility is a key feature of the friction-modifying material section 250. Customers can select the type of material based on their intended use. For indoor environments, materials (of the friction-modifying material sections 250) like suede or synthetic suede provide the optimal balance R2024-105-PCT (GC) of slide and grip on dance floors. For outdoor use, more durable polymers can be chosen to withstand rougher surfaces while maintaining the desired friction properties. Polymers may be formulated to be non-marking, water-resistant, and to maintain low-friction properties even on damp or wet surfaces. The replaceable nature of the friction-modifying material section 250 allows users to switch between different materials over time, adapting their footwear to various environments or preferences.

[0155] Such an exemplary design allows dancers to use fashionable trainers or sneakers, integrating the replaceable friction-modifying material without altering the shoe’s aesthetic. Unlike existing dance trainers, which can be expensive and require full replacement when worn out, the present disclosure allows for the easy replacement of the friction-modifying material section 250, extending the footwear's lifespan and reducing costs. The recessed area 240 and the friction-modifying material section 250 are designed to be unobtrusive, preserving the original appearance of the footwear. Dancers can wear the shoes they prefer while benefiting from the necessary friction properties for dancing, without compromising style, performance, or cost-effectiveness.

[0156] Ease of maintenance is an advantage of this exemplary sole 210 design. The worn frictionmodifying material section 250 can be replaced by users themselves without professional assistance or special tools. The replacement process is straightforward, as depicted in FIG. 11, which can involve the process of a) removing the worn friction-modifying material section 250 by peeling it away from the recessed area 240, b) cleaning any residual adhesive or debris from the recessed area 240 to ensure a clean surface, c) applying a new friction-modifying material section 250, which may come with a pre-applied adhesive layer, into the recessed area 240; and d) firmly pressing the frictionmodifying material section 250 to secure the adhesive fastening mechanism 255, ensuring the material protrudes appropriately from the bottom surface 215. Referring to FIG. 17, a registration / indexing guide 142 on the section 150 and the recessed area 140 cooperates to align the section for one-time placement within the recess. Adhesives may include PSA or PSA transfer film; pressing along the smooth perimeter sealing land ensures adhesive wet-out, while an optional microtextured coplanar field provides interlock and may incidentally assist traction when the section is absent. The section may include an edge chamfer or bevel to reduce peel initiation and increase local contact pressure. The chamfer is optional and may be favored for additively manufactured or machined sections; other embodiments employ a square edge. Indexing indicia or non-rotationally symmetric outlines may be used to guide one-time placement and resist rotation during use. This user-friendly maintenance process reduces long-term costs and downtime, allowing dancers to maintain optimal shoe performance without interruption. R2024-105-PCT (GC)

[0157] Referring to FIG. 12 A, an exemplary footwear sole structure 400 of a shoe 50 of the present disclosure comprises a sole 410 fabricated using manufacturing techniques, including but not limited to 3D printing techniques from flexible materials. The sole 410 includes various regions, such as a heel portion 420, midfoot portion 425, and forefoot portion 430, defining a bottom surface 415. fhe sole 410 includes multiple recessed areas 440 defined within its bottom surface 415, corresponding to areas where the friction-modifying material sections 450 are to be applied. Integrated holes 445 are visible and defined within these recessed areas 440, contributing to weight reduction and enhanced flexibility. The holes 445 are strategically placed beneath the replaceable friction-modifying material sections 450 to reduce weight and enhance flexibility without compromising structural integrity. Importantly, the holes 445 may not extend entirely through the sole 410; they can be internal cavities or extend partially through the sole 410, covered by subsequent layers during the manufacturing process.

[0158] In FIG. 12B, a cross-sectional view of an exemplary sole 410 is illustrated, showing the replaceable friction-modifying material sections 450 positioned within the recessed areas 440. The upper shoe material (50) is indicated by dashed lines to be affixed to the sole (410). The integrated holes (445) are not visible in this figure, as they may be internal or covered by layers of the sole 410.

[0159] FIG. 12C presents a cross-sectional view of an exemplary sole 410, showing an additional middle layer 460 of different material sandwiched between the top and bottom layers of the sole 410. This middle layer 460 alters the sole 410’s properties, such as flexibility, cushioning, or stiffness, by introducing a material with different characteristics. The replaceable friction-modifying material sections 450 are positioned within the recessed areas 440. The upper shoe material 50 is indicated by dashed lines. The integrated holes 445 may be located within any of the layers and may not extend through the entire thickness of the sole 410.

[0160] FIG. 13 provides an exploded view of an exemplary footwear sole 410, illustrating the bottom surface 415 with recessed areas 440 and integrated holes 445. The holes 445 may be internal or partially extending through the sole 410. The assembly process of positioning the replaceable friction-modifying material sections 450 over the recessed areas 440 is depicted, showing how the sections 450 cover the holes 445 and are affixed within the recessed areas 440. Fastening mechanisms are not shown in this figure.

[0161] The friction-modifying material section 250 is a thin layer, only a few millimeters thick, and is adjacent to the sole 210. It does not replace or alter any structural components of the sole 210. The sole 210 remains at its usual thickness, and its structural strength is unaffected, maintaining the integrity of the footwear (shoe 50). This is a key distinction from the prior art, where the replacement involves substantial parts of the sole that arc integral to the shoe's structure. R2024-105-PCT (GC)

[0162] The friction-modifying material sections 250 can be produced separately from the shoe using advanced manufacturing techniques such as CNC machining, mass production methods, and 3D printing. CNC machining and 3D printing enable on-demand production and customization of the friction-modifying material sections 250, allowing manufacturers to produce components tailored to individual shoe designs and sizes without the need for standardization. These components may be standardized or customized depending on manufacturing and stocking strategy. This customization facilitates the production of different material options, such as indoor or outdoor friction-modifying materials, providing customers with a choice at the time of purchase or the ability to switch materials later.

[0163] The use of advanced manufacturing techniques offers several benefits, including a) precision, which ensures a perfect fit of the friction-modifying material section 250 within the recessed area 240, enhancing performance and durability, b) customization, which allows for the creation of friction-modifying materials with specific properties, sizes, and shapes to suit individual preferences or requirements, and c) economic efficiency, which reduces manufacturing costs by enabling on- demand production and minimizing inventory requirements.

[0164] The friction-modifying material section 250 can be affixed within the recessed area 240 using an adhesive fastening mechanism 255. Adhesives are preferred as the fastening mechanism due to their reliability, ease of use, and minimal addition to the depth or complexity of the recess. In certain embodiments, adhesives are used exclusively. Alternative fastening mechanisms, such as mechanical interlocks, snap-fit connectors, and magnetic fasteners, may also be used where compatible. In adhesive embodiments, the adhesive may be carried on the section and / or disposed on the recess floor (e.g., transfer film); the diagrammatic placement in the figures is not limiting.

[0165] The recessed area 240 protects the edges of the friction-modifying material section 250, reducing wear and preventing peeling or detachment during rigorous dance movements. This protective feature enhances durability, ensuring that the friction-modifying material remains securely in place, even under the stresses of performance. In some embodiments, the adhesive forms a continuous perimeter band aligned with the sealing land to enhance edge seal integrity and peel resistance.

[0166] Environmental benefits arise from this design by reducing waste. Instead of discarding entire shoes or large portions of the sole when the friction-modifying material wears out, only a small component needs to be replaced. This reduction in material consumption contributes to sustainability efforts and lessens the environmental impact associated with footwear production and disposal.

[0167] Safety considerations are addressed through the maintenance of consistent friction properties. Worn-out soles can lead to uneven friction, increasing the risk of slips and falls. By allowing easy R2024-105-PCT (GC) replacement of the friction-modifying material, the shoe maintains optimal traction and stability, enhancing safety during dance performances.

[0168] In some embodiments, kits are provided comprising one or more replacement sections, instructions for removal and installation using adhesive (e.g., PSA or transfer film), and optionally a surface-preparation wipe, primer, or adhesive remover. The instructions may include indexing guidance for accurate one-time placement.

[0169] In some embodiments, used footwear is refurbished by (i) receiving footwear comprising a sole with at least one recessed area and a replaceable friction-modifying section; (ii) separating a worn upper from the sole: (iii) inspecting the sole and recessed area to confirm dimensional integrity and structural soundness; (iv) cleaning the sole and recessed area and, where desired, removing residual adhesive and applying a primer; (v) affixing a replacement upper to the sole; and (vi) replacing the used section with a replacement section adhesively affixed in the recessed area. In at least one embodiment, inspection includes verifying that a recessed area depth is not more than about 2 millimeters and that, when installed, a replacement section protrudes by at least about 0.5 millimeter. Refurbished footwear may be offered for sale at reduced cost relative to new footwear, thereby extending sole life and reducing material waste.

[0170] While various embodiments of products and methods for using and making the same have been described in considerable detail herein, the embodiments are merely offered as non-limiting examples of the disclosure described herein. It will therefore be understood that various changes and modifications may be made, and equivalents may be substituted for elements thereof, without departing from the scope of the present disclosure. The present disclosure is not intended to be exhaustive or limiting with respect to the content thereof.

[0171] Further, in describing representative embodiments, the present disclosure may have presented a method and / or a process as a particular sequence of steps. However, to the extent that the method or process docs not rely on the particular order of steps set forth therein, the method or process should not be limited to the particular sequence of steps described, as other sequences of steps may be possible. Therefore, the particular order of the steps disclosed herein should not be construed as limitations of the present disclosure. In addition, disclosure directed to a method and / or process should not be limited to the performance of their steps in the order written. Such sequences may be varied and still remain within the scope of the present disclosure.

Claims

R2024-105-PCT (GC)CLAIMS1. A footwear sole structure comprising: a sole including a heel portion and a forefoot portion and defining a bottom surface; and at least two recessed areas defined within the bottom surface of the sole, with at least one recessed area of the at least two recessed areas located in the forefoot portion and at least one recessed area of the at least two recessed areas located in the heel portion; wherein the at least two recessed areas are configured to receive a replaceable frictionmodifying material section therein.

2. The footwear sole structure of claim 1, further comprising: at least two replaceable friction-modifying material sections respectively positioned in the at least two recessed areas.

3. The footwear sole structure of claim 2, wherein each recessed area provides a substantially smooth or planar adhesion surface at a floor thereof, the adhesion surface being configured to promote adhesive wet-out and secure bonding of a friction-modifying material section affixed therein by a pressure-sensitive adhesive, a pressure-sensitive adhesive transfer film, or another adhesive fastening mechanism, and wherein adhesion surfaces within the recessed areas are structurally and functionally distinct from textured tread surfaces of the surrounding bottom surface that are configured to provide traction and ground contact when at least one replaceable section is absent.

4. The footwear sole structure of claim 2, wherein the friction-modifying material sections have a thickness greater than a depth of the corresponding recessed areas such that the sections protrude beyond adjacent outsole surfaces, and wherein the recessed areas are positioned at weight-bearing locations such that ground contact during normal use occurs primarily through external surfaces of the friction-modifying material sections, thereby concentrating wear on the replaceable sections and protecting an underlying sole structure.

5. The footwear sole structure of claim 2, wherein the recessed areas correspond to the forefoot portion and the heel portion of the sole.

6. The footwear sole structure of claim 1, wherein the footwear remains wearable with the replaceable sections absent by virtue of the shallow recessed areas and adjacent outsole surfaces configured to provide ground contact when a section is absent.

7. The footwear sole structure of claim 1, wherein low-profile tread elements are provided adjacent a recessed area to provide ground contact when a replaceable section is absent.

8. The footwear sole structure of claim 7, wherein the tread elements that are present within a recessed area are substantially coplanar with a recess floor.R2024-105-PCT (GC)9. The footwear sole structure of claim 1, wherein a midfoot region between the forefoot and heel recessed areas comprises a ground-contacting tread region configured to provide baseline traction and maintain wearability when the replaceable sections are absent.

10. The footwear sole structure of claim 2, wherein each replaceable section is affixed within a corresponding recessed area by an adhesive selected from the group consisting of a pressure-sensitive adhesive and a pressure-sensitive adhesive transfer film.

11. The footwear sole structure of claim 10, wherein each replaceable section is affixed exclusively by adhesive.

12. The footwear sole structure of claim 10, wherein the adhesive forms a continuous perimeter band aligned with a sealing land.

13. The footwear sole structure of claim 2, further comprising: a fastening mechanism configured to fasten each replaceable section within each recessed area.

14. The footwear sole structure of claim 13, wherein the fastening mechanism is selected from the group consisting of adhesives, mechanical interlocks, snap-fit connectors, and magnetic fasteners, thereby permitting removal and replacement of each replaceable section.

15. The footwear sole structure of claim 1, wherein each recessed area has a depth of about 2 millimeters or less.

16. The footwear sole structure of claim 15, wherein each recessed area has a depth of about 1 millimeter.

17. The footwear sole structure of claim 1, wherein at least one recessed area has a depth of about 3 millimeters or less.

18. The footwear sole structure of claim 2, wherein at least one replaceable section protrudes beyond adjacent outsole surfaces by at least about 0.5 millimeter.

19. The footwear sole structure of claim 2, wherein at least one replaceable section has a thickness of about 2 millimeters to about 2.5 millimeters.

20. The footwear sole structure of claim 2, wherein at least one replaceable section has a thickness of up to about 5.0 millimeters to provide increased grip.

21. The footwear sole structure of claim 2, wherein at least one replaceable section protrudes beyond adjacent outsole surfaces by no more than about 5.0 millimeters.

22. The footwear sole structure of claim 21, wherein the protrusion is no more than about 4.5 millimeters.

23. The footwear sole structure of claim 21, wherein the protrusion is no more than about 4.0 millimeters.R2024-105-PCT (GC)24. The footwear sole structure of claim 1 , wherein at least one recessed area includes a smooth perimeter sealing land configured to promote adhesive wet-out and inhibit moisture ingress.

25. The footwear sole structure of claim 24, wherein the sealing land has a width of about 2 millimeters to about 20 millimeters.

26. fhe footwear sole structure of claim 1, wherein at least one recessed area further includes an inward, low-relief microtextured central field that is substantially coplanar with a recess floor and configured to improve adhesive interlock.

27. The footwear sole structure of claim 26, wherein the microtexture has a height of not more than about 0.2 millimeter.

28. The footwear sole structure of claim 1, wherein at least one of (i) a recessed area and (ii) a replaceable section includes indexing indicia or a non-rotationally symmetric outline configured to guide single -placement alignment and resist rotation within the recessed area.

29. The footwear sole structure of claim 28, wherein the recessed area and the replaceable section are keyed to each other by a non-rotationally symmetric geometry to resist misalignment.

30. The footwear sole structure of claim 2, wherein at least one replaceable section is formed of a material selected from the group consisting of suede, synthetic suede, microfiber, and polymeric materials.

31. The footwear sole structure of claim 30, wherein the polymeric material is a flexible, low- friction composition selected to provide glide suitable for dancing.

32. The footwear sole structure of claim 31, wherein the composition is non-marking.

33. The footwear sole structure of claim 31, wherein the composition is formulated to mimic the glide characteristics of suede while offering increased durability.

34. The footwear sole structure of claim 31, wherein the composition is water-resistant and maintains low-friction properties on indoor and outdoor surfaces, including damp or wet surfaces.

35. The footwear sole structure of claim 2, wherein the replaceable section is replaceable with different materials to adapt the footwear for indoor or outdoor use.

36. The footwear sole structure of claim 2, wherein the replaceable sections are manufactured by additive manufacturing, cutting from molded or extruded sheet, or Computer Numerical Control (CNC) machining from sheet stock.

37. The footwear sole structure of claim 2, wherein the replaceable sections are standardized in geometric shape and size to allow compatibility with multiple shoe sizes and designs.

38. The footwear sole structure of claim 2, wherein at least one replaceable section includes micro-lugs or fine siping configured to increase grip while preserving flexibility.R2024-105-PCT (GC)39. The footwear sole structure of claim 2, wherein the section at the forefoot portion and the section at the heel portion have different coefficients of friction.

40. The footwear sole structure of claim 2, wherein the section at the forefoot portion and the section at the heel portion are formed of different materials.41 . fhe footwear sole structure of claim 2, wherein the section at the forefoot portion and the section at the heel portion protrude by different heights to provide contrasting friction engagement.

42. The footwear sole structure of claim 2, wherein the sole defines a toe-area cut-out aligned with the forefoot section.

43. The footwear sole structure of claim 2, further comprising: one or more additional recessed areas defined within the bottom surface of the sole and one or more additional replaceable sections each positioned within a corresponding additional recessed area.

44. The footwear sole structure of claim 1, wherein the sole defines holes therein beneath at least one recessed area to reduce weight and enhance flexibility, the holes being internal cavities or extending partially through the sole and covered by a replaceable section to prevent debris ingress.

45. The footwear sole structure of claim 44, wherein at least one replaceable section is secured within a recessed area by a fastening mechanism selected from the group consisting of adhesives, mechanical interlocks, snap-fit connectors, and magnetic fasteners.

46. The footwear sole structure of claim 1, wherein the sole includes a middle layer of material positioned between top and bottom layers to tune flexibility, cushioning, or torsional rigidity.

47. The footwear sole structure of claim 1, wherein the recessed areas and replaceable sections are standardized in geometry across shoe models to simplify resupply of replacement sections.

48. The footwear sole structure of claim 1 , wherein the sole has a design selected from the group consisting of a flat sole design with a continuous bottom surface, a split sole design, and a raised heel design.

49. The footwear sole structure of claim 48, wherein in the split sole design the heel and forefoot portions are discrete sole elements connected by an upper.

50. The footwear sole structure of claim 1, wherein walls of at least one recessed area shield edges of a replaceable section from external contact to reduce peel initiation.

51. A footwear sole structure comprising: a sole including a heel portion and a forefoot portion and defining a bottom surface: a single shallow recessed area formed within the bottom surface of the sole, extending across a substantial portion of the sole between the forefoot portion and the heel portion; andR2024-105-PCT (GC) a replaceable thin friction-modifying material section positioned within the single shallow recessed area, the friction-modifying material section having a thickness greater than a depth of the recessed area such that the friction-modifying material section protrudes from the bottom surface of the sole; wherein the friction-modifying material section is affixed within the recessed area using an adhesive fastening mechanism; and wherein the friction- modifying material section is adjacent to the sole and does not replace or alter any structural components of the sole.

52. The footwear sole structure of claim 51, wherein the footwear remains wearable when the friction-modifying material section is absent by virtue of the shallow recessed area and adjacent outsole surfaces configured to provide ground contact when the section is absent.

53. The footwear sole structure of claim 51, wherein low-profile tread elements are provided adjacent the recessed area to provide ground contact when the replaceable section is absent.

54. The footwear sole structure of claim 53, wherein the tread elements that are present within the recessed area are substantially coplanar with the recess floor.

55. The footwear sole structure of claim 51, wherein the single shallow recessed area has a depth of about 2 millimeters or less.

56. The footwear sole structure of claim 55, wherein the depth is about 1 millimeter.

57. The footwear sole structure of claim 51, wherein the friction-modifying material section has a thickness of about 2 millimeters to about 2.5 millimeters.

58. The footwear sole structure of claim 51, wherein the friction-modifying material section has a thickness of up to about 5.0 millimeters, with an installed protrusion of about 5.0 millimeters or less.

59. The footwear sole structure of claim 58, wherein the installed protrusion is capped at about 4.5 millimeters.

60. The footwear sole structure of claim 58, wherein the installed protrusion is capped at about 4.0 millimeters.

61. The footwear sole structure of claim 51, wherein the friction-modifying material section protrudes beyond adjacent outsole surfaces by at least about 0.5 millimeter.

62. The footwear sole structure of claim 51, wherein the single shallow recessed area includes a smooth perimeter sealing land and an inward, substantially coplanar low-relief microtextured central field.

63. The footwear sole structure of claim 51 , wherein the adhesive includes a continuous perimeter band dimensioned to overlie the scaling land.R2024-105-PCT (GC)64. The footwear sole structure of claim 51, wherein the friction-modifying material section includes an edge chamfer or bevel.

65. The footwear sole structure of claim 51, wherein at least one of (i) the recessed area and (ii) the friction-modifying material section includes indexing indicia or a non-rotationally symmetric outline configured to guide single-placement alignment and resist rotation within the recessed area.

66. The footwear sole structure of claim 51, wherein the friction-modifying material section includes micro-lugs or fine siping configured to increase grip while preserving flexibility.

67. The footwear sole structure of claim 51, wherein the friction-modifying material section is formed of a material selected from the group consisting of suede, synthetic suede, microfiber, and non-marking polymeric materials formulated for glide or grip.

68. The footwear sole structure of claim 51, wherein the friction-modifying material section is replaceable with different materials to adapt the footwear for indoor or outdoor use.

69. The footwear sole structure of claim 51, wherein the friction-modifying material section is affixed exclusively by adhesive, the adhesive fastening mechanism maintaining the flexibility of the sole.

70. A replaceable friction-modifying section for installation in a recessed area of a footwear sole, the section comprising: a section body formed of a material selected to provide a coefficient of friction different from that of surrounding outsole surfaces; and an adhesive on a mounting face, including a pressure-sensitive adhesive or a pressuresensitive adhesive transfer film, configured to bond the section to the recessed area; wherein the section body has a thickness of about 2 millimeters to about 2.5 millimeters and, upon installation, protrudes beyond adjacent outsole surfaces by at least about 0.5 millimeter.

71. The replaceable friction-modifying section of claim 70, wherein the section body has a thickness of up to about 5.0 millimeters.

72. The replaceable friction-modifying section of claim 70, wherein upon installation the section protrudes between about 0.5 millimeter and about 5.0 millimeters.

73. The replaceable friction-modifying section of claim 70, wherein the section body includes an edge chamfer or bevel.

74. The replaceable friction-modifying section of claim 70, wherein the section body is non- rotationally symmetric in outline to resist rotation within the recessed area.

75. The replaceable friction-modifying section of claim 70, wherein the section body comprises a material selected from the group consisting of suede, synthetic suede, microfiber, or a non-marking polymeric material.R2024-105-PCT (GC)76. The replaceable friction-modifying section of claim 70, wherein the section body is additively manufactured, cut from a molded or extruded sheet, or Computer Numerical Control (CNC) cut from sheet stock.

77. The replaceable friction-modifying section of claim 70, wherein a surface of the section body includes micro-lugs or fine siping configured to increase grip while preserving flexibility.

78. The replaceable friction-modifying section of claim 70, wherein the adhesive includes a continuous perimeter adhesive band dimensioned to overlie a sealing land of the recessed area.

79. A kit, comprising: one or more replaceable friction-modifying sections sized for recessed areas of a footwear sole; and instructions for removing a used section and applying a replacement section using an adhesive, including a pressure-sensitive adhesive or a pressure-sensitive adhesive transfer film.

80. The kit of claim 79, further comprising a surface-preparation wipe, primer, or adhesive remover.81 . The kit of claim 79, wherein the one or more replaceable friction-modifying sections comprise replacement sections of the same friction property.

82. The kit of claim 79, wherein the one or more replaceable friction-modifying sections comprise replacement sections of different friction properties.

83. The kit of claim 79, wherein the one or more replaceable friction-modifying sections comprise replacement sections of different thicknesses.

84. The kit of claim 79, wherein the instructions include guidance for aligning a section using indexing indicia.

85. A method of tuning traction characteristics of footwear, comprising: removing a used replaceable section from a recessed area of a footwear sole; cleaning the recessed area; and affixing a replacement section in the recessed area using an adhesive, including a pressuresensitive adhesive or a pressure-sensitive adhesive transfer film, the replacement section having a thickness greater than a depth of the recessed area such that the replacement section protrudes beyond adjacent outsole surfaces.

86. The method of claim 85, further comprising pressing the replacement section to form a seal along a perimeter sealing land and to engage a low-relief microtextured central field.

87. The method of claim 85, further comprising priming the recessed area prior to affixing the replacement section.R2024-105-PCT (GC)88. The method of claim 85, further comprising aligning the replacement section using indexing indicia.

89. The method of claim 85, wherein the replacement section is selected to provide a lower or a higher coefficient of friction relative to surrounding outsole surfaces.

90. A method of manufacturing a footwear sole structure comprising: forming a sole including a heel portion and a forefoot portion and defining a bottom surface; creating at least two recessed areas into the bottom surface of the sole at the heel portion and the forefoot portion; and positioning a replaceable friction-modifying material section shaped to fit within each recessed area of the at least two recessed areas, wherein the replaceable friction-modifying material sections protrude from a bottom surface of the sole.

91. The method of claim 90, further comprising producing a friction-modifying material section separately from the sole using a manufacturing technique selected from Computer Numerical Control (CNC) machining, additive manufacturing, or cutting from molded or extruded sheet.

92. The method of claim 90, further comprising creating a cutout in a front toe area of the sole shaped as a crescent or other suitable geometry to align with the replaceable friction-modifying material section at the forefoot portion.

93. The method of claim 90, further comprising affixing the replaceable friction-modifying material sections within the recessed areas using a fastening mechanism selected from adhesives, mechanical interlocks, snap-fit connectors, and magnetic fasteners.

94. A method of refurbishing footwear, comprising: receiving used footwear comprising a sole defining at least one recessed area and a replaceable friction-modifying section; removing an upper from the sole; inspecting the sole to confirm the recessed area remains within a depth specification and the sole is structurally sound; cleaning the sole and the recessed area; and affixing a replacement upper to the sole.

95. The method of claim 94, further comprising replacing the used friction-modifying section with a replacement section adhesively affixed in the recessed area.

96. The method of claim 94, wherein inspection comprises verifying that the recessed area has a depth of not more than about 2 millimeters and that, when installed, a replacement section protrudes by at least about 0.5 millimeter.R2024-105-PCT (GC)97. The method of claim 94, further comprising removing residual adhesive and applying a primer to at least one surface before affixing the replacement upper.

98. The method of claim 94, further comprising offering the refurbished footwear for sale.

99. Refurbished footwear, comprising: a previously used sole defining at least one recessed area configured to receive a replaceable friction-modifying section; and a replacement upper affixed to the sole.

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