WO2003071893A1

WO2003071893A1 - Adaptive grip

Info

Publication number: WO2003071893A1
Application number: PCT/GB2003/000846
Authority: WO
Inventors: Iain James Sabberton; Peter David Cauwood; Dominic George Webber; Peter Georg Laitenberger; Steven Roland Brace; Kevin Huw Hilton; Neil John Smith
Original assignee: Generics Investment Group Ag; The University Of Northumbria At Newcastle Commercial Enterprises Limited
Priority date: 2002-02-28
Filing date: 2003-02-28
Publication date: 2003-09-04
Also published as: AU2003208460A1

Abstract

A shoe sole and stud assembly are provided in which studs are mounted on a spring member of the sole which provides cushioning to the user during use. In a preferred embodiment, the spring member (15-5) includes at least one primary stud (7-5) and one or more secondary studs (9-5, 11-5) which operate to engage with the ground when an impact force causes the primary stud to deform towards the sole of the shoe. In this way, additional grip can be provided on varying surface conditions.

Description

ADAPTIVE GRIP

The present invention relates to an apparatus for providing adaptive grip on a variety of surfaces. The invention has particular although not exclusive relevance to cleats or studs provided on the sole of footwear such as football boots.

In the field of sports footwear, it is known to provide studs on the sole of each shoe to increase the ability of the user to grip the surface whether the user is trying to remain still or move. The term studs used throughout this application applies to all protrusions from the sole of the shoe or boot which may be circular, wedged shaped, spikes, etc., which function to increase traction between the user and the ground. In some countries, such studs are commonly referred to as cleats.

A user generally selects the length, size, pattern, shape, number and distribution of such studs in accordance with the ground conditions in which the footwear is to be used. The most common arrangements are

"screw-in" studs, "moulded" studs, "astroturf" grip and

"trainer" grip. The choice relies on the user making an accurate assessment of the ground conditions and requires the user to have several pairs or shoes available. To eliminate the requirement for multiple pairs of shoes, it is also known in the art to vary the length of the studs prior to usage by adjusting a plate underneath the sole. However, both of these methods require a choice to be made prior to usage and are based on the average ground conditions.

Further, as users demand lighter and more flexible sports footwear, the soles are becoming thinner as a result. When studs are provided on the sole of the shoes, this can increase the likelihood of injury to the user, because the force of impact of the shoe on the ground is transmitted through the stud to a localised part of the foot.

Additionally, footwear users are sometimes injured due to excessive lateral forces applied to the lower leg. This situation, occurs during a user's normal activities such as, for example, suddenly changing direction.

The present invention aims to address one or more of these problems and to provide an alternative grip/stud assembly for the sole of a shoe.

In one aspect, the present invention provides a stud assembly having a rocking member coupled to a stud which is spring biassed to act against forces transmitted through the stud during use.

In another aspect the present invention provides a stud assembly having a primary stud and at least one secondary stud, wherein force applied to the primary stud causes the secondary stud to be engaged towards the ground. Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which like reference numbers are used to designate like parts and in which:

Figure 1 is a perspective view of a football boot having a stud assembly embodying the present invention;

Figure 2A is an exploded view of the stud assembly forming part of the football boot shown in Figure 1 and illustrating a first manufacturing step in which the parts of the stud assembly are assembled;

Figure 2B illustrates a second manufacturing step in which the stud assembly is moulded within the sole for the football boot shown in Figure 1 ;

Figure 2C illustrates a third manufacturing step in which an elastomer is used to fill the gaps between the stud assembly shown in Figure 2A and the sole of the football boot;

Figure 2D schematically illustrates a third manufacturing step in which a section of resilient foam is provided underneath a primary stud of the stud assembly shown in Figure 2A;

Figure 3A is a cross sectional view of part of the football boot shown in Figure 1 taken along the line x-x during use of the football boot on soft ground; Figure 3B is a cross sectional view of part of the football boot shown in Figure 1 taken along the line x-x during use of the football boot on hard ground;

Figure 4 is a cross sectional view of part of the football boot shown in Figure 1 taken along the line y-y during use of the football boot on soft ground;

Figure 5 is a perspective view showing part of a football boot having a stud assembly embodying the present invention;

Figure 6 is an exploded view of the football boot shown in Figure 5;

Figure 7 is a perspective view of a hiking boot employing a stud assembly embodying the present invention;

Figure 8A is a cross sectional view of an alternative stud assembly embodying the invention comprising studs mounted on a dome shaped spring plate;

Figure 8B is a cross sectional view of the stud assembly shown in Figure 8A showing the deformation of the dome shaped spring plate when impact force is applied to the primary stud;

Figure 9A is a cross sectional view of a further alternative stud assembly embodying the invention comprising a primary stud attached to a base via a rotatable spring member;

Figure 9B is a cross sectional view of the stud assembly shown in Figure 9A showing the rotation of the spring member when impact force is applied to the primary stud;

Figure 10A is a cross sectional view of a further alternative stud assembly embodying the invention comprising an elastic block between the base with pivot points and a stud bearing member that is coupled to the base at the pivot points; and

Figure 10B is a cross sectional view of the stud assembly shown in figure 10A showing the deformation of the elastic block and the rotation of the stub bearing member around the pivot points of the base.

First Embodiment

Figure 1 is a perspective view illustrating a football boot 1 having six stud assemblies 3-1 to 3-6 moulded within a moulded semi-rigid plastic sole 5. Two of the stud assemblies 3-1 and 3-2 are provided at the heel of the sole 5 whilst the remaining four stud assemblies 3-3 to 3-6 are provided at the front of the sole 5. As shown in Figure 1, each stud assembly 3 comprises a primary stud 7 and two smaller secondary studs 9 and 11 on either side of the primary stud 7. In this embodiment, each of the stud assemblies 3 is arranged so that the three studs

7, 9 and 11 are arranged in a line substantially parallel to an outer edge 13 of the sole 5. In this embodiment, the three studs are attached to a spring plate 15-1 to 15-6 shown in phantom in Figure 1. As will be described in further detail below, an inner edge of the spring plate 15 is moulded and attached to the sole 5 whilst the outer edge (on which the three studs are mounted) is free to flex to allow relative movement between the primary stud 7 and the secondary studs 9 and 11. As will be described in more detail below, this relative movement allows the football boot to vary the traction provided to the user under varying ground conditions. In addition, the spring plate 15 acts to distribute impact forces experienced by the user during use over a larger area of the sole 5, thereby reducing the likelihood of injury to the user. Further advantages of the stud assemblies 3 will become apparent from the following detailed description.

Stud Assembly

The components and manufacture of the stud assemblies 3 will be now described with reference to Figure 2.

Figure 2A illustrates in more detail the components of one of the stud assemblies 3. As shown in Figure 2, the primary stud 7 has a generally cylindrical shape with a circular cross-section and has a snap-on barbed end 21 for engagement with the hole 23 on the spring plate 15. Similarly, the secondary studs 9 and 11 also have a general cylindrical shape with a substantially circular cross-section and have a snap-on barbed end 21 for engagement with respective holes 25 and 27 on the spring plate 15. In this embodiment, the primary stud 7 and the two secondary studs 9 and 11 are made of a hard plastic material so that they are resistant to general wear and tear through normal use of the football boot 1.

As shown in Figure 2A, the holes 23, 25 and 27 for receiving the studs 7, 9 and 11 respectively are arranged along the longer edge 29 of the spring plate 15. The stud assembly 3 is then formed by snap fitting the barbed ends 21 of the primary stud 7 and the secondary studs 9 and 11 into the respective receiving holes 23, 25 and 27. As shown in Figure 2A, the spring plate 15 also includes two additional holes 31 and 33 provided at the narrower edge 35 of the spring plate 15. As will be described in more detail below, these help to anchor the spring plate 15 into the sole 5.

After the studs have been fitted to the spring plates 15, the six stud assemblies 3-1 to 3-6 are placed in an appropriate mould (not shown). A liquid plastic is then poured into the mould and allowed to solidify around the stud assemblies 3 to form the sole 5 of the football boot. Figure 2B shows part of the resulting sole 5 having the stud assembly 3 embedded into a section thereof. In this embodiment, the mould tool used in the moulding process is arranged so that each stud assembly 3 is only attached to the sole 5 at the narrower edge 35 thereof and along four strip sections (two of which are shown and labelled 41 and 43) which extend across each stud assembly 3 on either side thereof. As will be described in more detail, the two strip sections which are not shown in Figure 2B and which are provided below the stud assembly 3 act as fulcrums about which the spring plate 15 can flex. The two upper strips 41 and 43 are provided for holding the stud assembly 3 within the sole 5.

As shown in Figure 2B after the first moulding operation, spaces 45a, 45b and 45c are provided around each of the studs. These spaces are then filled in a second moulding operation with an elastomer which provides a water-tight seal around the primary stud 7 and the secondary studs 9 and 11. Figure 2C illustrates the elastomer 47 which is formed within the spaces 45 shown in Figure 2B.

Finally, as shown in Figure 2D, a piece of resilient foam 49 is inserted into a space 51 provided underneath the primary stud 7 on the inside surface of the sole 5 that is attached to the rest of the football boot 1. Figure 2D also shows the other two strips 53 and 55 discussed above about which the spring plate 15 flexes during use.

Operation

The way in which stud assembly 3 described above operates in different ground conditions will now be described. Figure 3A is a cross sectional view of stud assembly 3-5 shown in Figure 1 taken along line x-x when the user is standing on soft ground 61. As shown, the primary stud 7 penetrates the surface 63 of the soft ground, with the force of the impact being transmitted along the primary stud 7 to the spring plate 15 and then along the strips 53 and 55 to the sole 5 of the shoe where the force is then transmitted to the user's foot. Some of the force impact is also absorbed by the elastomer 47 and the foam 49 formed in the sole 5. In this way, the force transmitted through the primary stud 7 is not transmitted directly to the user's foot but is distributed over a larger area around the primary stud 7 , which reduces strain on the user's foot which in turn can reduce long term injuries.

When the user is on hard ground, the primary stud 7 will not penetrate (or will do so to a lesser extent) the surface 63 of the ground 61. The impact force therefore causes the spring plate 15 to deform away from its normal shape allowing the primary stud 7 to move towards and into the resilient foam member 49. As shown in Figure 3B, when the spring plate 15 deforms it flexes as the portions around the strips 53 and 55 rotate about the strips 53 and 55. As a result, some of the impact force is absorbed by the spring plate 15 and the resilient foam member 49, thereby reducing the impact force transmitted through to the user's foot. Further, as the spring plate flexes the outer edges 65 and 67 of the spring plate move away from the sole 5 towards the ground 61, thereby causing the secondary studs 9 and 11 to engage with the ground 61. As those skilled in the art will appreciate, this engagement of the secondary studs with the ground increases the traction between the ground 61 and the football boot 1 and also increases the contact area with the ground thereby spreading the impact load further.

When the user lifts their foot, the impact force on the primary stud 7 is removed. The bias in the spring plate 15 causes it to return back into its original shape (shown in Figure 3A) .

Figure 4 is a cross-sectional view of stud assembly 3-5 along the line y-y shown in Figure 1. As can be seen from Figure 4, the narrow edge portion 35 is the only portion of the spring plate 15 which is embedded within the sole 5. The remainder of the spring plate 15 is surrounded by the elastomer 47 and held in place by the upper and lower strips 41, 43, 53 and 55. With this arrangement and as described above, the portion of the stud assembly 3 around the primary stud 7 forms a spring board which, in addition to providing cushioning for forces applied perpendicular to the ground through the stud 7, also provides some resistance to lateral forces applied to the stud 7 parallel the ground. For example, lateral force in the direction of the primary stud 7 to the narrow edge portion 35 would cause the primary stud 7 to flexibly rotate outwards away from the sole 5 whilst a lateral force applied in the other direction would cause the primary stud 7 to flexibly rotate inwards towards the foam member 49. As a result, the forces experienced by the user when the user is making sharp turns or manoeuvres is reduced, thereby reducing the likelihood of injury. Second Embodiment

In the first embodiment described above, the stud assemblies were moulded within the sole of the shoe during manufacture. As those skilled in the art will appreciate, this is not essential, the stud assemblies may be assembled within the sole of the shoe during manufacture using discrete components. This is illustrated in the second embodiment shown in Figures 5 and 6. In particular, Figures 5 and 6 illustrate the various subcomponents of the stud assemblies used in this embodiment. As shown in these Figures, each stud assembly 103-1 to 103-4 includes a primary stud 107 and two secondary studs 109 and 111. As shown in Figure 6, these studs are received in and attached to a respective spring member 115-1, 115-2, 115-3 and 115-4. Further, as shown in Figure 6, the spring members 115-2 and 115-3 are connected together to form a single composite spring member which holds the studs of the respective assemblies. Similarly, spring members 115-1 and 115-4 are also connected together to form a composite spring member for holding the corresponding studs.

In this embodiment, the stud assemblies also include a respective flexible plastic cover portion 147-1 to 147-4 which protect the metal spring plates 115 and which prevent the ingress of water and dirt ingress. As shown in Figures 5 and 6, these plastic cover members 147 extend through a rigid plastic outer sole 150 which attaches to the sole 105 to hold the components of the stud assembly in place. As shown in Figure 6, the sole 105 includes, for each stud assembly, a pair of fulcrum blocks 153 and 155 about which the spring member 115 can rotate.

The spring member 115 shown in Figure 6 operates in the same way as the spring plate used in the first embodiment. In particular, the spring member 115 is arranged so that when assembled in the sole, an inside limb 161 is fixed to the sole 105 whilst the outer limbs 163 are free to move relative to the sole 105. When a user is walking on hard ground, impact forces applied to the primary studs 107 are transmitted through to the outer limbs 163 of the spring plates 115 which cause them to move (rotate) towards the sole 105 against the fulcrum blocks 153 and 155. This movement also causes the outer edges 165 to flexibly rotate away from the sole 105 thereby causing the secondary studs 109 and 111 to move away from the sole 105 and to engage with the ground.

MODIFICATIONS AND ALTERNATIVE EMBODIMENTS

In the above embodiments, a football boot has been described in which two secondary studs have been mounted on either side of a primary stud on a leaf spring which is embedded within the sole of the football boot. As those skilled in the art will appreciate, the stud assembly used in the above embodiments can be applied to various different types of shoes. For example, the stud assembly may be used in a hiking boot, such as the one shown in Figure 7, where the secondary studs are spikes which are arranged to engage with the ground when the user is on hard ground such as ice.

In the first embodiment described above, a planar spring plate was used as part of the stud assembly. As those skilled in the art will appreciate, it is not essential to have a spring member that is exactly planar. The edges of the spring member may be bent inwards towards the sole or outwards away from the sole in order to vary the amount of movement of the studs located on these edge portions towards and away from the sole.

In the above embodiments, a number of stud assemblies have been described which provide cushioning to the user by mounting one or more studs on a spring plate which, in use, flexes to absorb impact forces. The spring plate is arranged relative to the sole of the shoe so that it rotates relative to the sole thereby absorbing some of the impact forces. As those skilled in the art will appreciate, it is possible to achieve a similar cushioning effect with other types of stud assemblies. For example, Figures 8A and 8B schematically illustrate in cross-section an alternative stud assembly 303. As shown in Figure 8A, the stud assembly includes a primary stud 307 and two secondary studs 309 and 311 which are attached to a dome shaped spring plate 315 which is attached at its base 317 to the sole 305 of the shoe.

Figure 8A illustrates the form of the stud assembly 303 when there is no impact force applied to the primary stud 307. However, when an impact force is applied to the primary stud 307, the dome shaped spring plate 315 will initially absorb the force distributing it across the dome to the sole 305 at its base 317. However, as the impact force increases the dome shaped spring plate 315 will collapse towards a toroid shape (as shown in Figure 8B) such that the primary stud 307 moves towards the sole 305. As those skilled in the art will appreciate, the amount of impact force that the dome shaped spring plate 315 can absorb before it collapses will depend on the curvature and material of the dome shaped spring plate 315 and the compressibility of any filler material inside the dome. As those skilled in the art will appreciate, part of the cushioning provided to the primary stud 307 is also achieved, in this embodiment, through the rotation (rolling) of the spring plate 315 about the base 317. Further, and as shown in Figure 8B, as the primary stud 307 moves towards the sole 305, the sides of the dome shaped spring plate 315 push out away from the sole 305 causing the secondary studs 309 and 311 to move towards the ground, thereby increasing the traction provided by the stud assembly 303.

When the impact force is removed from the primary stud 307, the energy stored in the spring plate 315 causes it to resume its dome shape (shown in Figure 8A) , pushing the primary stud away from the sole 305.

Figure 9 schematically illustrates another alternative stud assembly which provides cushioning to a primary stud 407 through the rotation of an appropriate spring member 415 relative to the sole 405 of the shoe. In particular, in the embodiment shown in Figure 9A, stud 407 is mounted to a projection 417 of a rigid base plate 419 which is attached to the sole 405. A spring member 415 is provided for spring biassing the stud 407 away from the sole 405. A stop member (not shown) is provided for preventing the stud 407 from detaching from the projection 417.

When an impact force is applied to the stud 407, it is transmitted through the stud 407 to the spring member 415 causing a first leg portion 421 of the spring member 415 to slide away from the stud 407 and to rotate towards the base 419. This causes the spring member 415 to compress through the rotation of a second leg portion 423 and a connecting member 425 which connects the second leg portion 423 to the first leg portion 421. As can seen from Figures 9A and 9B, this rotation reduces the angle α which, due to the semi-rigid nature of the leg portions 421 and 423 and the connecting member 425, results in some of the impact energy being absorbed and stored in the spring member 415. Additionally, as shown in Figure 9B, when the impact force is applied to the primary stud 407, the outer end 427 of the second leg portion 423 rotates away from the sole 405 towards the ground, thereby acting like a secondary stud.

When force is removed from the primary stud 407, the energy stored in the spring member 415 causes the second leg portion 423 and the connecting member 425 to push apart (increasing the angle α), which in turn causes the first leg portion 421 to push the primary stud 407 away from the sole 405 back to the position shown in Figure 9A.

As shown in Figure 9, in this embodiment, a second spring member 431 is also provided on the other side of the projection 417 which operates in the same manner as the spring member 415 and will not therefore, be described again.

Figure 10 illustrates a further alternative stud assembly 503, which includes a rigid base 519 which is attached to the sole 505 of the shoe. The base 509 is shaped to provide two pivot points 521 and 523 about which an outer stud bearing portion 525 can pivot. As shown in Figure 10, the outer stud bearing portion 525 includes a primary stud 507 and two secondary studs 509 and 511 and can pivot about pivot points 521 and 523 to absorb impact forces transmitted through the primary stud 507. The stud bearing portion 525 also includes resilient hinge portions 533 and 535 which flex and which spring bias the primary stud 507 away from the sole 505 towards the ground. A cylindrical elastic block 527 is also provided within the primary stud 507 and acts against the base 519 to further spring bias the primary stud 507 away from the sole 505. A flexible skirt 531 is provided between the edge of the stud bearing portion 525 and the base 519, to prevent the ingress of mud and water. Figure 10A illustrates the stud assembly 503 when no force is applied to the primary stud 507. However, in use, when an impact force is applied to the primary stud 507, the stud bearing portion 525 rotates about the pivot points 521 and 523 compressing the elastic block 527. As a result, the primary stud 507 moves towards the sole 505 and the secondary studs 509 and 511 move away from the sole 505 towards the ground. When the impact force is removed, the compressed elastic block 527 expands and pushes against the stud bearing portion 525 returning the stud assembly to its original position shown in Figure 10A.

In the above embodiments, the primary studs are made of hard plastic for penetrating soft or loose ground. This is not essential. The primary studs can be made of softer plastics material to provide more cushioning and traction on hard but slippery surfaces.

In the above embodiments, a primary stud was provided on the spring member together with two secondary studs provided on either side of the primary stud. As those skilled in the art will appreciate, such a three-stud arrangement is not essential and any number of studs may be provided on each spring member. For example, multiple primary studs may be provided with only a single secondary stud. Alternatively, two primary studs may be provided at the edges of the spring member with a secondary stud provided in a central portion. The operation of such an embodiment would be the reverse to that of the first embodiment in that when force is applied to the two primary studs, the part of the spring member holding the primary studs will flex (rotate) in towards the sole whilst a central portion carrying the secondary stud will flex (rotate) out from the sole. Alternatively the stud assembly could be provided with no secondary studs.

In the above embodiments, impact forces applied to a primary stud were partially absorbed by a spring member which rotated against the sole of the shoe. The spring member was also arranged so that secondary studs coupled to the spring plate deployed when the primary stud moved towards the sole. As those skilled in the art will appreciate, in embodiments where such secondary studs are provided, the coupling of the secondary studs to the spring member may be achieved in any convenient manner. For example, an arrangement wedge shaped elements may be used to deploy the secondary studs when the primary stud moves against the spring member towards the sole. Alternatively still, the primary stud and the secondary studs may be arranged so that the physical deformation of the primary stud results in the deployment of the secondary studs, with the movement of the primary and secondary studs being dependent on the modulus and poissons ratio of the primary stud (hence the deformation per unit force) and the interaction between the primary and secondary studs.

In the first embodiment, the spring member used was made of pressed steel, but any deformable resilient element may be used. Examples include plastics, composites, laminated metal structures etc.

In the first embodiment described above, the studs are attached to the spring plate by snap-fitting a barbed end of the studs into a receiving hole on the spring plate. As those skilled in the art will appreciate, this is not essential. The studs can be attached to the spring plate by an appropriate means such as by riveting, insert moulding, heat staking, screwing, glue or chemical welding. The stud can also be formed as an integral feature of the spring member. Alternatively, the studs could be removable, allowing the user to replace broken or worn studs or to allow the user to select the studs based on the current playing conditions.

In the above embodiments, the primary studs were spring biassed away from the sole of the shoe by a spring member whose material and geometry defined the amount of bias that was provided. As those skilled in the art will appreciate, additional resilient members may be provided to give additional biassing. For example, a source of hoop stress (eg from a rubber band) may be provided around either the secondary studs (to prevent them from deploying) or around the primary stud (to prevent it from deforming when it is subjected to an impact force).

In the first embodiment described above, an elastomer was provided around the stud assembly which, because of its elastomeric nature causes the stud assembly to return to its original non-compressed state. However, a more viscous elastomer may be used so that the stud assembly returns to its non-compressed state more slowly, thereby providing increased traction for an extended period of time.

In the above embodiments, complete shoes are described which include the new stud assembly described herein. As those skilled in the art will appreciate, the sole together with the stud assemblies may be sold to a shoe manufacturer for integration with a shoe upper. Further, the stud assemblies themselves may be made and sold separately from the soles and then embedded in the soles at the time of manufacturing the shoe.

In the first embodiment described above, the spring plates were moulded within the sole of the shoe and then the sole was secured to the shoe upper to make the football boot. As those skilled in the art will appreciate, the sole and the shoe upper may be manufactured in a single moulding operation so that the sole and the upper are integrally formed.

Claims

CLAIMS :

1. A stud assembly for incorporation into the sole of a shoe, the assembly comprising: a base attachable to the sole; a spring member coupled to the base and rotatable between first and second positions; a stud coupled to the spring member and movable between an extended position when said spring member is in said first position and a retracted position when said spring member is in said second position; wherein said spring member is spring biassed towards said first position and wherein said stud is coupled to said spring member such that the spring bias of the spring member is transmitted to the stud to bias the stud towards said extended position.

2. A stud assembly according to claim 1, wherein during use, an impact force applied to the primary stud causes the spring member to rotate towards the second position and the primary stud to move towards the retracted position, against the spring bias applied to the spring member.

3. A stud assembly according to claim 1 or 2 , wherein the spring bias of the spring member acts at an angle to a direction of motion of the stud when moving between said extended and retracted positions.

4. A stud assembly according to claim 1, 2 or 3, arranged so that during use, an impact force applied to the stud is transmitted through said spring member to an area laterally adjacent the stud.

5. A stud assembly according to any preceding claim, wherein the spring member comprises a leaf spring.

6. A stud assembly according to claim 5, wherein the leaf spring is formed from pressed metal.

7. A stud assembly according to claim 5, wherein the leaf spring is formed from a laminate of a plurality of sheets of metal.

8. A stud assembly according to any preceding claim, wherein the spring member includes a fulcrum and a member rotatable about the fulcrum between said first and second positions.

9. A stud assembly according to claim 8, wherein the fulcrum means comprise at least two ridges on opposite sides of the stud.

10. A stud assembly according to claim 8, wherein the fulcrum is integrally formed with the base.

11. A stud assembly according to claims 1 to 4 or 8 to 10, wherein the spring member comprises a spring plate of resilient material that is dome shaped in said first position and that is operable to rotate towards a toroid shape in said second position.

12. A stud assembly according to claim 11, wherein the degree of spring biassing of the spring plate is dependent upon the material and curvature of the resilient material.

13. A stud assembly according to any preceding claim, wherein the stud is integrally formed with the spring member.

14. A stud assembly according to any preceding claim, wherein the spring member includes an elastic member which acts between the base and the stud to spring bias the stud towards the extended position.

15. A stud assembly according to any preceding claim, comprising two or more spring members located around the stud, each spring member being operable to spring bias the stud towards said extended position.

16. A stud assembly according to claim 15, wherein each spring member comprises at least two semi rigid linkage elements coupled together to provide said spring bias.

17. A stud assembly according to any preceding claim, wherein the stud has a circular cross-section.

18. A stud assembly according to any of claims 1 to 16, wherein the stud has a wedge shaped cross-section.

19. A stud assembly according to any preceding claim, wherein the stud has a barbed end for snap fitting into a hole of the spring member.

20. A stud assembly according to any of claims 1 to 18, wherein the stud is moulded onto the spring member.

21. A stud assembly according to any preceding claim, wherein the stud is substantially non-resilient.

22. A stud assembly according to any preceding claim, wherein said stud is a primary stud, and further comprising at least one secondary stud for additional grip.

23. A stud assembly according to claim 23, wherein said primary stud is operable to extend further from the base than the at least one secondary stud when said primary stud is in said extended position.

24. A stud assembly according to claim 22 or 23, wherein the difference of extent from the base between the primary stud and the at least one secondary stud is less when the primary stud is in said retracted position.

25. A stud assembly according to claim 22 or 23, wherein said at least one secondary stud extends an equal or greater distance from the base than the extent of said primary stud when said primary stud is in said retracted position .

26. A stud assembly according to any of claims 22 to 25, wherein the at least one secondary stud is mounted for movement towards and away from said base.

27. A stud assembly according to any of claims 22 to 26, wherein the at least one secondary stud is coupled to the spring member so that when said primary stud moves from said extended position towards said retracted position, said at least one secondary stud moves in an opposite direction away from said base.

28. A stud assembly according to any of claims 22 to 27, wherein the primary and secondary stud are not the same shape .

29. A stud assembly according to any of claims 22 to 28, wherein the at least one secondary stud is a spike.

30. A stud assembly according to any of claims 22 to 29, wherein two secondary studs are attached to the spring member on either side of the primary stud.

31. A stud assembly according to any preceding claim, further comprising dampening means located between the spring member and the sole and operable to dampen movement of the spring member and to absorb, during use, impact force transmitted though the stud.

32. A stud assembly according to any preceding claim, wherein the stud assembly further comprises a sealant for preventing the ingress of water.

33. A stud assembly according to claim 29, wherein the sealant is an elastomeric material.

34. A stud assembly for incorporation into the sole of a shoe, the assembly comprising: a base having a surface for attachment to the sole of the shoe; a primary stud and at least one secondary stud, wherein the primary stud and the at least one secondary stud are mounted for relative movement to the base between a first position in which the primary stud extends further from said surface of the base than the at least one secondary stud and a second position in which the difference of extent of the primary stud and the at least one secondary stud from said surface of the base is less than the difference of extent of the primary stud and the at least one secondary stud from said surface of the base in said first position; and means, responsive to force applied to the primary stud, for causing relative movement of said primary stud and said at least one secondary stud between said first and second positions.

35. A stud assembly for incorporation into the sole of a shoe, the assembly comprising: a base having a surface for attachment to the sole of the shoe; a primary stud and at least one secondary stud, wherein the primary stud and the at least one secondary stud are mounted for relative movement to the base between a first position in which the primary stud extends further from said surface of the base than the at least one secondary stud and a second position in which the extent of the at least one secondary stud from said surface of the base is equal to or greater than the extent of the primary stud from said surface of said base ; and means, responsive to force applied to the primary stud, for causing relative movement of said primary stud and said at least one secondary stud between said first and second positions.

36. A stud assembly according to claim 34 or 35, arranged so that a force applied to the primary stud causes the primary stud to move towards the base.

37. A stud assembly according to any of claims 34 to 36, wherein the primary stud is mounted on a spring member which is operable to spring bias the primary stud away from the base.

38. A stud assembly according to any of claims 34 to 37, wherein the at least one secondary stud is mounted to said spring member.

39. A stud assembly according to any of claims 34 to 38, wherein the stud assembly comprises two secondary studs on either side of the primary stud.

40. A stud assembly according to any of claims 34 to 39, wherein the primary stud or the at least one secondary stud has a circular cross-section.

41. A stud assembly according to any of claims 34 to 39, wherein the primary stud or the at least one secondary stud has a wedge shaped cross-section.

42. A stud assembly according to any of claims 34 to 41, wherein the primary and secondary stud are not the same shape.

43. A stud assembly according to any of claims 34 to 42, wherein the at least one secondary stud is a spike.

44. A stud assembly according to any of claims 34 to 43, wherein the primary stud or the at least one secondary stud has a barbed end for snap fitting into a hole of the spring member.

45. A stud assembly according to any of claims 34 to 43, wherein the primary stud or the at least one secondary stud are moulded into the spring member.

46. A stud assembly according to any of claims 34 to 45, wherein the primary stud or the at least one secondary stud are substantially non-resilient.

47. A stud assembly according to any of claims 34 to 46, wherein the primary stud or the at least one secondary stud are formed from a substantially rigid material.

48. A shoe sole comprising one or more stud assemblies according to any of claims 1 to 47.

49. A shoe sole according to claim 48, wherein the spring member is moulded to the sole.

50. A shoe sole according to claim 48, wherein the spring member is glued to the sole.

51. A shoe comprising one or more stud assemblies according to any of claims 1 to 46.

52. A method of making a sole for a shoe comprising: providing a plurality of stud assemblies, at least one of which is a stud assembly according to any of claims 1 to 47; and attaching the stud assemblies to a base to form the sole.

53. A method according to claim 52, wherein at least one of the stud assemblies is formed by the steps of; providing at least one stud, providing a spring member, attaching the at least one stud to the spring member to form the stud assembly.

54. A method according to claim 53, wherein the step of attaching the at least one stud to the spring member comprises the step of: snap fitting the at least one stud to the spring member .

55. A method according to claim 53, wherein the step of attaching the at least one stud to the spring member comprises the step of: heat moulding the at least one stud to the spring member .

56. A method according to any of claims 52 to 55, wherein at least one of the stud assemblies is formed by the step

attaching the at least one stud to a leaf spring.

57. A method according to claim 56 wherein, the step of attaching the stud assemblies to the base comprises the steps of: inserting the stud assemblies into predetermined locations of a moulding tool, injecting liquid plastic into the moulding tool to form around the stud assembly such that liquid plastic surrounds a fixed end of the leaf spring but does not surround a free end of the leaf spring, cooling the liquid plastic surrounding the stud assembly to form a semi rigid sole with the free end of the leaf spring movable relative to the sole.

58. A method according to claim 57, wherein the step of attaching the stud assemblies to the base further comprises the steps of: using a mould tool which results in maintaining spaces around at least a part of the stud assembly when liquid plastic is injected into the moulding tool, a second moulding operation to inject liquid elastomer into the moulding tool, cooling the liquid elastomer to form a seal to prevent the ingress of water and dirt into the stud assembly.

59. A method according to claims 56 or 57, wherein the step of attaching the stud assemblies to the base further comprises the steps of: using a mould tool which results in maintaining a space generally adjacent the stud, filling the created space with a dampening material.

60. A method according to claim 59, wherein the step of filling the created space comprises the step of: inserting a resilient material into the created space.

61. A method according to claim 59, wherein the step of filling the created space comprises the step of: moulding a resilient material into the created space.

62. A method of manufacturing a shoe comprising: providing a plurality of stud assemblies, at least one of which is a stud assembly according to any of claims 1 to 47; attaching the stud assemblies to a base to form the sole; and forming a shoe using an upper and a sole formed in the attaching step.