Article of footwear with increased torsional stiffness
By adding welts and/or heel clips to the soles and uppers, and using 3D printing technology to manufacture the soles, the problem of insufficient torsional stiffness in existing footwear products is solved, resulting in a significant improvement in the stability and comfort of the heel area.
Patent Information
- Application Number
- CN202410494217.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-23
- Publication Date
- 2025-10-24
AI Technical Summary
Existing footwear products lack sufficient torsional stiffness, making it difficult to effectively prevent torsion of the heel, which affects comfort and stability.
The soles are manufactured using 3D printing technology, and welts and/or heel clips are added to the soles and uppers to enhance the torsional stiffness of the shoes.
It significantly improves the torsional stiffness of the shoe by at least 100%, enhancing the shoe's stability and comfort.
Smart Images
Figure CN120827239A_ABST
Abstract
Description
[0001] Cross Reference to Related Applications
[0002] Not applicable.
[0003] Statement as to Federally Sponsored Research or Development
[0004] Not applicable.
[0005] Appendix
[0006] Not applicable. TECHNICAL FIELD
[0007] The present invention relates to an article of footwear having increased torsional stiffness. SUMMARY
[0008] One aspect of the disclosure provides a shoe. The shoe includes a sole, an upper secured to the sole, and a welt. The welt includes at least one component separate from the sole and the upper. The welt is adjacent to both the sole and the upper and is secured to at least one of the sole and the upper. The sole has a sole heel end and a sole toe end. The sole extends along a shoe axis from the sole heel end to the sole toe end. The sole has a sole heel region, a sole midfoot region, a sole forefoot region, a sole ball region, a sole metatarsal region, and a sole toe region. The sole heel region extends longitudinally from the sole heel end to the sole midfoot region. The sole midfoot region extends longitudinally from the sole heel region to the sole forefoot region. The sole forefoot region extends longitudinally from the sole midfoot region to the sole ball region. The sole ball region extends longitudinally from the sole forefoot region to the sole metatarsal region. The sole metatarsal region extends longitudinally from the sole ball region to the sole toe region. The sole toe region extends longitudinally from the sole metatarsal region to the sole toe end. The sole has a lateral side extending from the sole heel region to the sole toe region and a medial side extending from the sole heel region to the sole toe region. The sole extends laterally from the lateral side to the medial side. The sole heel region has a lateral heel portion and a medial heel portion. The sole midfoot region has a lateral midfoot portion and a medial midfoot portion. The sole forefoot region has a lateral forefoot portion and a medial forefoot portion. The sole ball region has a lateral ball portion and a medial ball portion. The sole metatarsal region has a lateral metatarsal portion and a medial metatarsal portion. The sole toe region has a lateral toe portion and a medial toe portion. The sole has a heel widest portion. The heel widest portion is a portion of the sole having a greatest width in the sole heel region from the medial side to the lateral side. The sole has a ball widest portion. The ball widest portion is a portion of the sole having a greatest width in the sole ball region from the medial side of the sole to the lateral side of the sole. The sole is a 3D printed sole including a plurality of interconnected cells. Each cell of the plurality of interconnected cells is connected to at least one adjacent cell of the plurality of interconnected cells. The sole has a sole top surface and a sole bottom surface. The sole has a perimeter extending between the sole top surface and the sole bottom surface. The shoe has a torsional stiffness. The torsional stiffness of the shoe is at least 100% greater than a torsional stiffness of a first comparative shoe. The first comparative shoe is identical to the shoe except that the first comparative shoe does not have a welt. The torsional stiffness is a torque sufficient to rotate the heel widest portion ten degrees (10°) from an untwisted state while the ball widest portion remains stationary.
[0009] Another aspect of the present disclosure provides a shoe. The shoe includes a sole, an upper secured to the sole, a quarter, and a heel clip. The quarter includes at least one component separate from the sole and the upper. The quarter is adjacent to both the sole and the upper and secured to at least one of the sole and the upper. The heel clip includes at least one component separate from the sole, the upper, and the quarter. The heel clip is secured to at least one of the sole and the upper at least in a heel region of the sole. The sole has a sole heel end and a sole toe end. The sole extends along a shoe axis from the sole heel end to the sole toe end. The sole has a sole heel region, a sole midfoot region, a sole forefoot region, a sole ball region, a sole metatarsal region, and a sole toe region. The sole heel region extends longitudinally from the sole heel end to the sole midfoot region. The sole midfoot region extends longitudinally from the sole heel region to the sole forefoot region. The sole forefoot region extends longitudinally from the sole midfoot region to the sole ball region. The sole ball region extends longitudinally from the sole forefoot region to the sole metatarsal region. The sole metatarsal region extends longitudinally from the sole ball region to the sole toe region. The sole toe region extends longitudinally from the sole metatarsal region to the sole toe end. The sole has a lateral side extending from the sole heel region to the sole toe region and a medial side extending from the sole heel region to the sole toe region. The sole extends laterally from the lateral side to the medial side. The sole heel region has a lateral heel portion and a medial heel portion. The sole midfoot region has a lateral midfoot portion and a medial midfoot portion. The sole forefoot region has a lateral forefoot portion and a medial forefoot portion. The sole ball region has a lateral ball portion and a medial ball portion. The sole metatarsal region has a lateral metatarsal portion and a medial metatarsal portion. The sole toe region has a lateral toe portion and a medial toe portion. The sole has a heel widest portion. The heel widest portion is a portion of the sole having a greatest width in the sole heel region from the medial side to the lateral side. The sole has a ball widest portion. The ball widest portion is a portion of the sole having a greatest width in the sole ball region from the medial side of the sole to the lateral side of the sole. The sole is a 3D printed sole including a plurality of interconnected cells. Each cell of the plurality of interconnected cells is connected to at least one adjacent cell of the plurality of interconnected cells. The sole has a sole top surface and a sole bottom surface. The sole has a perimeter extending between the sole top surface and the sole bottom surface. The shoe has a torsional stiffness. The torsional stiffness of the shoe is at least 100% greater than a torsional stiffness of a second comparative shoe. The second comparative shoe is identical to the shoe except that the second comparative shoe does not have a quarter and a heel clip. The torsional stiffness is a torque sufficient to rotate a heel widest portion ten degrees (10°) about the shoe axis from an untwisted state while the ball widest portion remains stationary.
[0010] Further features and advantages, as well as operation of the described implementations, are set forth in the detailed description which follows, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS
[0011] Figure 1 is a perspective view of a shoe.
[0012] Figure 2 is Figure 1 is a perspective view of a sole of a shoe shown.
[0013] Figure 3a is Figure 1 is a top view of a sole of a shoe shown.
[0014] Figure 3b is Figure 1 is a bottom view of a sole of a shoe shown.
[0015] Figure 4a is Figure 1 is a medial view of a sole of a shoe shown.
[0016] Figure 4b is Figure 1 is a lateral view of a sole of a shoe shown.
[0017] Figure 5a is Figure 1 is a front view of a sole of a shoe shown.
[0018] Figure 5b is Figure 1 is a rear view of a sole of a shoe shown.
[0019] Figure 6 is a perspective view of a comparative shoe.
[0020] Figure 7a is a schematic view of another embodiment of a shoe for which torsional stiffness was measured.
[0021] Figure 7b is Figure 7a is a rear view of a shoe shown rotated 0 degrees.
[0022] Figure 7c is Figure 7a is a rear view of a shoe shown rotated 5 degrees.
[0023] Figure 7d is Figure 7a is a rear view of a shoe shown rotated 10 degrees.
[0024] Figure 7e is a schematic view of a test procedure for measuring torsional stiffness of a shoe shown. Figure 7a
[0025] Figure 7f is a bottom view of a shoe shown prior to rotational stiffness testing. Figure 7a
[0026] is a bottom view of a shoe shown prior to rotational stiffness testing.Figure 8 isometric view of another embodiment of a shoe.
[0027] Figure 9 is a comparative view showing soles of a comparative shoe, a shoe with a welt, and a shoe with a welt and a heel clip.
[0028] Figure 10 is another embodiment of a shoe.
[0029] Corresponding reference characters indicate corresponding parts throughout the written description and drawings. DETAILED DESCRIPTION
[0030] Embodiments of a shoe according to the present disclosure are generally indicated by reference numeral 20. The shoe 20 includes a sole 22, an upper 24 secured to the sole, and a welt 26.
[0031] The upper 24 can include a medial side 24M or a lateral side 24L.
[0032] The welt 26 includes at least one component separate from the sole 22 and the upper 24. The welt 26 is adjacent to both the sole 22 and the upper 24, and is secured to at least one of the sole and the upper. The welt 26 can be secured to both the sole 22 and the upper 24. The welt 26 can be bonded to the sole 22 and / or the upper 24 by an adhesive. Alternatively or additionally, the welt can be secured to the sole 22 and / or the upper 24 by stitching. The welt 26 can constitute a single, unitary component. The welt 26 can include leather or Salpa. Optionally, the welt 26 can include a polymeric material, such as ethylene-vinyl acetate (EVA) or thermoplastic polyurethane (TPU). The welt 26 can include a plurality of welt slits. The welt 26 can be a storm welt.
[0033] The sole 22 has a sole heel end 28 and a sole toe end 30. The sole 22 extends along a shoe axis X from the sole heel end 28 to the sole toe end 30. The sole 22 has a sole heel region 32, a sole midfoot region 34, a sole forefoot region 36, a sole ball region 38, a sole metatarsal region 40, and a sole toe region 42. The sole heel region 32 extends longitudinally from the sole heel end 28 to the sole midfoot region 34. The sole midfoot region 34 extends longitudinally from the sole heel region 32 to the sole forefoot region 36. The sole forefoot region 36 extends longitudinally from the sole midfoot region 34 to the sole ball region 38. The sole ball region 38 extends longitudinally from the sole forefoot region 36 to the sole metatarsal region 40. The sole metatarsal region 40 extends longitudinally from the sole ball region 38 to the sole toe region 42. The sole toe region 42 extends longitudinally from the sole metatarsal region 40 to the sole toe end 30.
[0034] The sole 22 has a lateral side 22L extending from the sole heel region 32 to the sole toe region 42 and a medial side 22M extending from the sole heel region to the sole toe region. The sole 22 extends laterally from the lateral side 22L to the medial side 22M. The sole heel region 32 has a lateral heel portion 32L and a medial heel portion 32M. The sole midfoot region 34 has a lateral midfoot portion 34L and a medial midfoot portion 34M. The sole forefoot region 36 has a lateral forefoot portion 36L and a medial forefoot portion 36M. The sole ball region 38 has a lateral ball portion 38L and a medial ball portion 38M. The sole metatarsal region 40 has a lateral metatarsal portion 40L and a medial metatarsal portion 40M. The sole toe region 42 has a lateral toe portion 42L and a medial toe portion 42M.
[0035] The sole 22 has a heel widest portion 44. The heel widest portion 44 is the portion of the sole 22 having the greatest width in the sole heel region 32 from the medial side 32M to the lateral side 32L.
[0036] The sole 22 has a ball widest portion 46. The ball widest portion 46 is the portion of the sole 22 having the greatest width in the sole ball region 38 from the medial side 38M of the sole to the lateral side 38L of the sole.
[0037] The sole 22 is a 3D printed sole including a plurality of interconnected units 48. Each unit of the plurality of interconnected units 48 is connected to at least one adjacent unit of the plurality of interconnected units. The sole 22 can be 3D printed by stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), hindered asynchronous light synthesis (HALS), or the like.
[0038] The sole 22 has a sole top surface 50 and a sole bottom surface 52. The sole 22 has a perimeter 54 extending between the sole top surface 50 and the sole bottom surface 52.
[0039] The shoe 20 has a torsional stiffness. The torsional stiffness of the shoe 20 is at least 100% greater than the torsional stiffness of a first comparative shoe (not shown). Alternatively, the torsional stiffness of the shoe 20 can be at least 150% greater than the torsional stiffness of the first comparative shoe. Alternatively, the torsional stiffness of the shoe 20 can be 200% greater than the torsional stiffness of the first comparative shoe. Alternatively, the torsional stiffness of the shoe 20 can be at least 250% greater than the torsional stiffness of the first comparative shoe. Alternatively, the torsional stiffness of the shoe 20 can be at least 300% greater than the torsional stiffness of the first comparative shoe. The first comparative shoe is identical to the shoe 20 except that the first comparative shoe does not have a strip. The torsional stiffness is the torque sufficient to rotate the heel widest portion 44 ten degrees (10°) from an untwisted state while the ball widest portion 46 remains stationary.
[0040] The torsional stiffness can be determined by placing the shoe 20 in a fixture such that the ball of the foot widest portion 46 remains stationary (e.g., via Figures 7a to 7d The heel clamp 88 and Figure 7a The forefoot clamp 90) shown. The heel clamp 88 is supported (not shown) to rotate about a longitudinal axis X2 extending through the upper Figure 7a 、 7b A torsion sensor (not shown) can also be operably attached to the heel clamp 88. A downward force G of 50 Newtons is applied to the top surface of the sole in the heel region of the sole. A horizontal lateral force F is then applied to the medial side 24M of the upper 24 to create a torque for determining the medial side torsional stiffness, or to the lateral side 24L of the upper to create a torque for determining the lateral side torsional stiffness. The force F is applied to the upper 24 in a direction perpendicular to the shoe axis X at a location that is aligned with the heel widest portion 44 and adjacent the periphery 54. The force F is increased until the heel widest portion 44 of the shoe 20 is rotated ten degrees (10°) from its position prior to the application of the force (un-torqued state). Figure 7b The un-torqued state is shown in Figure 7c The torque that creates a 5° rotation is shown in Figure 7d The torque that creates a 10° rotation is shown in. The angle is measured via the angle monitoring sensor 92. This method is performed with a first comparison shoe and a shoe that is identical to the first comparison shoe but has a strip along the shoe. As described in more detail below, this method can also be performed with a second comparison shoe and a shoe that is identical to the second comparison shoe but has a strip along the shoe and a heel clamp. The results of the former test are shown below.
[0041]
[0042] In the above example, the strip includes leather. It can be appreciated from the results that the presence of the strip increases the torsional stiffness by at least over 200% compared to the first comparison shoe.
[0043] Referring to Figure 7e The distance of the PQ marker line to the back end of the heel is 25% of the total length of the shoe. The CD marker line passes through the AB marker line from a salient point inside the shoe. To calculate the relevant torque, the distance between the line CD and the line PQ is measured in millimeters to the nearest 0.5 millimeter. This distance represents the torque length L of the shoe 20. Then, the torque is calculated by the formula M = L x F, where M is the torque, L is the torque length, and F is the force required to rotate the shoe 10°.
[0044] The upper has an upper heel region 56, an upper midfoot region 58, a forefoot region 60, an upper ball region 62, an upper metatarsal region 64, and an upper toe region 66. The sole 22 and the upper 24 define a seam 68. The seam 68 has a seam heel region 70 adjacent to the upper heel region 56 and the sole heel region 32. The seam 68 has a seam midfoot region 72 adjacent to the upper midfoot region 58 and the sole midfoot region 34. The seam 68 has a seam forefoot region 74 adjacent to the forefoot region 60 and the sole forefoot region 36. The seam 68 has a seam metatarsal region 76 adjacent to the upper ball region 62 and the sole ball region 38. The seam 68 has a seam metatarsal region 78 adjacent to the upper metatarsal region 64 and the sole metatarsal region 40. Seam 68 has a seam toe region 80 adjacent to upper toe region 66 and sole toe region 42. A welt extends along and covers seam heel region 70, seam midfoot region 72, seam forefoot region 74, seam ball region 76, seam metatarsal region 78, and seam toe region 80.
[0045] The sole 22 may include an insole 84 and an outsole 86. The insole 84 and outsole 86 may be integral structures. For example, the insole 84 and outsole 86 may be formed as a single piece using a 3D printing process. Alternatively, the insole 84 and outsole 86 may include separate components connected together. The connection may include adhesive bonding, thermal bonding, etc. If the components are separate, the outsole may be a 3D printed structure or a molded structure. If the outsole is a molded structure, it may include rubber, thermoplastic polyurethane (TPU), or ethylene vinyl acetate (EVA).
[0046] Figure 8 and Figure 9 Another embodiment of a shoe is shown generally at 120. Figure 8 and Figure 9 The differences mentioned in the description of the embodiments, Figure 1 The above description of the article of footwear 20 of FIG. 7 is also applicable to the article of footwear 120. It should also be understood that, except for Figure 8 and Figure 9 The reference numerals of the embodiments include the prefix "1", Figure 8 and Figure 9 The reference numerals for components, elements, features, or regions of the embodiments correspond to Figure 1 7 to 7.
[0047] Shoe 120 also includes a heel clip 182. Heel clip 182 includes at least one component separate from sole 122, upper 124, and welt 126. Heel clip 182 is secured to at least one of sole 122 and upper 124 at least in sole heel region 132.
[0048]
[0049] In the above example, the stay includes leather and the heel clip includes thermoplastic polyurethane (TPU). It can be appreciated from the results that the presence of the stay and the heel clip increases the torsional stiffness by at least over 300% compared to the second comparative shoe.
[0050] In view of the above, it will be appreciated that the present application has numerous advantages over the prior art.
[0051] It will also be appreciated that when referring to elements of the present application in the claims or above description of exemplary embodiments of the application, the terms "comprising," "including," and "having" are intended to be open-ended and to mean that other elements besides the listed elements can be present. Also, the use of the term "part" should be interpreted to mean some or all of the item or element it is defining. Furthermore, the use of identifiers such as first, second, and third should not be interpreted as imposing any relative position or time sequence between the limitations.
[0052] Various modifications can be made to the structures and methods described and illustrated herein, without departing from the scope of the present application, and it is understood that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Thus, the breadth and scope of the present application should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
Claims
1. A shoe, the shoe comprising: a sole; an upper, the upper secured to the sole; and a stay; the stay comprising at least one component separate from the sole and the upper, the stay adjacent to both the sole and the upper and secured to at least one of the sole and the upper; the sole having a sole heel end and a sole toe end, the sole extending along a shoe axis from the sole heel end to the sole toe end, the sole having a sole heel region, a sole midfoot region, a sole forefoot region, a sole ball region, a sole metatarsal region, and a sole toe region, the sole heel region extending longitudinally from the sole heel end to the sole midfoot region, the sole midfoot region extending longitudinally from the sole heel region to the sole forefoot region, the sole forefoot region extending longitudinally from the sole midfoot region to the sole ball region, the sole ball region extending longitudinally from the sole forefoot region to the sole metatarsal region, the sole metatarsal region extending longitudinally from the sole ball region to the sole toe region, the sole toe region extending longitudinally from the sole metatarsal region to the sole toe end, the sole having a lateral side extending from the sole heel region to the sole toe region and a medial side extending from the sole heel region to the sole toe region, the sole extending laterally from the lateral side to the medial side, the sole heel region having a lateral heel portion and a medial heel portion, the sole midfoot region having a lateral midfoot portion and a medial midfoot portion, the sole forefoot region having a lateral forefoot portion and a medial forefoot portion, the sole ball region having a lateral ball portion and a medial ball portion, the sole metatarsal region having a lateral metatarsal portion and a medial metatarsal portion, the sole toe region having a lateral toe portion and a medial toe portion, the sole having a heel widest portion, the heel widest portion being a portion of the sole having a maximum width in the sole heel region from the medial side to the lateral side, the sole having a ball widest portion, the ball widest portion being a portion of the sole having a maximum width in the sole ball region from the medial side of the sole to the lateral side of the sole; the sole being a 3D printed sole comprising a plurality of interconnected units, each unit of the plurality of interconnected units connected to at least one adjacent unit of the plurality of interconnected units, the sole having a sole top surface and a sole bottom surface, the sole having a perimeter extending between the sole top surface and the sole bottom surface; and wherein the shoe has a torsional stiffness that is at least 100% greater than a torsional stiffness of a first comparative shoe, the first comparative shoe identical to the shoe except that the first comparative shoe is devoid of a stay, the torsional stiffness being a torque sufficient to rotate the heel widest portion ten degrees (10°) from an untwisted state while the ball widest portion remains stationary.
2. The shoe of claim 1, wherein, the stay constitutes a single unitary component.
3. The shoe of claim 1, wherein, The upper includes an upper heel region, an upper midfoot region, an upper forefoot region, an upper ball region, an upper metatarsal region, and an upper toe region, the sole and the upper defining a seam, the seam having a seam heel region adjacent the upper heel region and the sole heel region, a seam midfoot region adjacent the upper midfoot region and the sole midfoot region, a seam forefoot region adjacent the upper forefoot region and the sole forefoot region, a seam ball region adjacent the upper ball region and the sole ball region, a seam metatarsal region adjacent the upper metatarsal region and the sole metatarsal region, and a seam toe region adjacent the upper toe region and the sole toe region; and wherein the welt extends along and covers the seam heel region, the seam midfoot region, the seam forefoot region, the seam ball region, the seam metatarsal region, and the seam toe region.
4. The shoe of claim 3, wherein, The welt is secured to both the sole and the upper.
5. The shoe of claim 3, wherein, The welt is bonded to the sole with an adhesive.
6. The shoe of claim 3, wherein, The welt includes leather.
7. The shoe of claim 3, wherein, The welt includes a polymeric material.
8. The shoe of claim 3, wherein, The welt includes ethylene-vinyl acetate.
9. The shoe of claim 3, wherein, The welt includes a thermoplastic polyurethane.
10. The shoe of claim 3, wherein, The welt includes a plurality of welt slits.
11. The shoe of claim 3, wherein, The welt is a high-welt.
12. The shoe of claim 1, further comprising a heel clip, the heel clip including at least one component separate from the sole, the upper, and the welt, the heel clip being secured to at least one of the sole and the upper at least in the sole heel region.
13. The shoe of claim 1, wherein, The torsional stiffness of the shoe is at least 150% greater than the torsional stiffness of the comparative shoe.
14. The shoe of claim 1, wherein, The torsional stiffness of the shoe is at least 200% greater than the torsional stiffness of the comparative shoe.
15. The shoe of claim 1, wherein, The torsional stiffness of the shoe is at least 250% greater than the torsional stiffness of the comparative shoe.
16. The shoe of claim 1, wherein, The torsional stiffness of the shoe is at least 300% greater than the torsional stiffness of the comparative shoe.
17. A shoe, the shoe comprising: a sole; an upper secured to the sole; a welt; and a heel clip; the welt including at least one component separate from the sole and the upper, the welt being adjacent to both the sole and the upper and secured to at least one of the sole and the upper; the heel clip including at least one component separate from the sole, the upper, and the welt, the heel clip being secured to at least one of the sole and the upper at least in a sole heel region. The sole has a sole heel end and a sole toe end, the sole extending along a shoe axis from the sole heel end to the sole toe end, the sole having a sole heel region, a sole midfoot region, a sole forefoot region, a sole ball region, a sole metatarsal region, and a sole toe region, the sole heel region extending longitudinally from the sole heel end to the sole midfoot region, the sole midfoot region extending longitudinally from the sole heel region to the sole forefoot region, the sole forefoot region extending longitudinally from the sole midfoot region to the sole ball region, the sole ball region extending longitudinally from the sole forefoot region to the sole metatarsal region, the sole metatarsal region extending longitudinally from the sole ball region to the sole toe region, the sole toe region extending longitudinally from the sole metatarsal region to the sole toe end, the sole having a lateral side extending from the sole heel region to the sole toe region and a medial side extending from the sole heel region to the sole toe region, the sole extending laterally from the lateral side to the medial side, the sole heel region having a lateral heel portion and a medial heel portion, the sole midfoot region having a lateral midfoot portion and a medial midfoot portion, the sole forefoot region having a lateral forefoot portion and a medial forefoot portion, the sole ball region having a lateral ball portion and a medial ball portion, the sole metatarsal region having a lateral metatarsal portion and a medial metatarsal portion, the sole toe region having a lateral toe portion and a medial toe portion, the sole having a heel widest portion, the heel widest portion being a portion of the sole having a maximum width in the sole heel region from the medial side to the lateral side, the sole having a ball widest portion, the ball widest portion being a portion of the sole having a maximum width in the sole ball region from the medial side of the sole to the lateral side of the sole; The sole is a 3D printed sole comprising a plurality of interconnected units, each unit of the plurality of interconnected units being connected to at least one adjacent unit of the plurality of interconnected units, the sole having a sole top surface and a sole bottom surface, the sole having a perimeter extending between the sole top surface and the sole bottom surface; and wherein the shoe has a torsional stiffness that is at least 100% greater than a torsional stiffness of a second comparative shoe, the second comparative shoe being identical to the shoe except that the second comparative shoe does not have a strip and a heel clip, the torsional stiffness being a torque sufficient to rotate the heel widest portion ten degrees (10°) about the shoe axis from an untwisted state while the ball widest portion remains stationary.
18. The shoe of claim 17, wherein, The torsional stiffness of the shoe is at least 150% greater than the torsional stiffness of the comparative shoe.
19. The shoe of claim 17, wherein, The torsional stiffness of the shoe is at least 200% greater than the torsional stiffness of the comparative shoe.
20. The shoe of claim 17, wherein, The torsional stiffness of the shoe is at least 250% greater than the torsional stiffness of the comparative shoe.
21. The shoe of claim 17, wherein, The torsional stiffness of the shoe is at least 300% greater than the torsional stiffness of the comparative shoe.
22. The shoe of claim 17, wherein, The sole comprises an inner sole and an outer sole, the inner sole being 3D printed and comprising a plurality of interconnected units, the outer sole being connected to the inner sole.
23. The shoe of claim 22, wherein, The outer sole comprises rubber.