TIGHTENING STRAP FOR SKI BOOTS AND SKI BOOT PROVIDED WITH SUCH STRAP

Abstract

Tightening strap for ski boots adapted to be wound in a loop around the cuff of a ski boot to tighten said cuff on the user's leg; the tightening strap comprising an oblong flexible element, which is adapted to be wound around the cuff and includes at least one elastic member with auxetic behaviour formed by an oblong plate-like body, which has a monolithic structure and is divided into a plurality of contiguous flat sectors, each of which has a macroscopic reticular structure with auxetic behaviour, which structure is capable of stretching and, at the same time, also of widening in elastic manner when the oblong plate-like body is subjected to traction, and also differs from that of the adjacent flat sectors.

Claims

1. Tightening strap for ski boots adapted to be wound in a loop around the cuff of a ski boot to tighten said cuff on the user's leg; the tightening strap comprising an oblong flexible element, which is adapted to be wound around the cuff and includes at least one elastic member with auxetic behaviour able to stretch and, at the same time, also to widen in elastic manner when the tightening strap is subjected to traction; the tightening strap wherein said elastic member with auxetic behaviour comprises an oblong plate-like body, which has a monolithic structure and is divided into a plurality of contiguous flat sectors, each of which has a macroscopic reticular structure with auxetic behaviour, which is capable of stretching and, at the same time, also of widening in elastic manner when the oblong plate-like body is subjected to traction, and also differs from that of the adjacent flat sectors.

2. Tightening strap according to claim 1, wherein the macroscopic reticular structure with auxetic behaviour of said flat sectors is a two-dimensional reticular structure.

3. Tightening strap according to claim 1, wherein the macroscopic reticular structure with auxetic behaviour of each flat sector differs from that of the adjacent flat sectors in shape and/or dimensions.

4. Tightening strap according to claim 1, wherein said oblong flexible element is longitudinally divided into at least a first segment with substantially inextensible structure, and into at least a second segment incorporating said oblong plate-like body.

5. Tightening strap according to claim 4, wherein the second segment of said oblong flexible element comprises an oblong and flexible plate-like element, which is made of plastic material and is longitudinally divided into a central section incorporating said oblong plate-like body, and into two opposite lateral sections that seamlessly join to said central section, on opposite sides thereof.

6. Tightening strap according to claim 4, wherein one or both of the opposite lateral sections of the oblong plate-like element are structured so as to channel the tensile stresses in a series of prefixed and limited points of the central section of the same oblong plate-like element.

7. Tightening strap according to claim 4, wherein one or both of the opposite lateral sections of the oblong plate-like element have a sunburst-like structure converging towards the free end of the oblong plate-like element.

8. Tightening strap according to claim 1, wherein it additionally comprises a manually-operated fastening device, which is adapted to connect the opposite ends or end portions of the oblong flexible element one to the other in a stable, though releasable manner.

9. Tightening strap according to claim 8, wherein said fastening device is stably placed at a first end or end portion of the oblong flexible element, and is structured so as to connect in a stable, though releasable manner, to a second end or end portion of the same oblong flexible element, opposite to said first end.

10. Tightening strap according to claim 8, wherein said fastening device is fixed to said first end or end portion of the oblong flexible element in a manually adjustable manner.

11. Ski boot comprising: a substantially rigid foot-case, which is adapted to accommodate the user's foot; a substantially rigid cuff, which is adapted to surround the lower part of the user's leg, and is hinged on the foot-case so as to swing about a first rotation axis (A) substantially perpendicular to the ski-boot midplane; a protective inner-boot (103), which is placed inside the foot-case and is shaped/structured so as to accommodate and protect at least the user's foot; and manually-operated closing means that are structured so as to selectively tighten the foot-case and/or cuff, respectively, on the user's foot and leg; said closing means comprising a tightening strap, that surrounds the cuff so as to selectively close/tighten the cuff on the user's leg; the ski boot wherein the tightening strap is realized according to claim 1.

12. Ski boot according to claim 11, wherein the tightening strap is fitted/fixed on the cuff in a removable manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will now be described with reference to the annexed drawings, which illustrate a non-limiting embodiment thereof, in which:

[0017] FIG. 1 is a perspective view of a ski boot provided with a tightening strap realized according to the teachings of the present invention;

[0018] FIGS. 2 and 3 are perspective views of the tightening strap that tightens the upper part of the cuff of the ski boot shown in FIG. 1;

[0019] FIG. 4 is a plan view of the tightening strap shown in FIGS. 2 and 3, with parts removed for clarity's sake.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] With reference to FIGS. 1, 2 and 3, number 1 denotes as a whole a tightening strap for ski boots, which is particularly adapted to elastically tighten the upper part of the cuff of a ski boot 100. In addition, the ski boot 100 can be advantageously used for practising ski mountaineering or Telemark.

[0021] In more detail, the ski boot 100 firstly comprises: a substantially rigid foot-case 101, which is shaped substantially like a shoe so as to accommodate/contain the user's foot, and advantageously has its lower part specifically shaped/structured to couple/fasten in a rigid and stable, though easy releasable manner, to a ski binding device of known type (not shown) or similar, which in turn is rigidly fixed on the back of a generic downhill ski or similar; and a substantially rigid cuff 102, which is shaped so as to surround the lower part of the user's leg, and is hinged on the foot-case 101 so as to freely swing about a transversal rotation axis A, which is locally substantially perpendicular to the ski-boot vertical midplane, and is preferably also substantially coincident with the articulation axis of the user's ankle.

[0022] In more detail, the cuff 102 is hinged on the foot-case 101 so as to freely swing back and forth while remaining in a swinging plane orthogonal to the rotation axis A and substantially coincident with the ski-boot vertical midplane.

[0023] In addition, the ski boot 100 further comprises: a protective inner-boot 103 preferably with a soft and/or thermal-insulating structure, which is placed within the foot-case 101 and preferably also the cuff 102, and is shaped/structured so as to accommodate/enclose and protect the foot and preferably also the lower part of the user's leg; and manually-operated closing means that are structured to selectively close/tighten the foot-case 101 and the cuff 102, respectively, on the user's foot and leg.

[0024] The protective inner-boot 103, in particular, is adapted to prevent the foot and advantageously also the user's leg from coming into direct contact with the foot-case 101 and/or the cuff 102, and preferably also to minimise heat loss to the outside.

[0025] The manually-operated closing means, on the other hand, are adapted to immobilise the user's foot and leg inside the ski boot 100, or rather inside the protective inner-boot 103.

[0026] In addition, the ski boot 100 is preferably moreover provided with a manually-operated cuff locking device 105, which is preferably fixed on the rear part of the cuff 102, advantageously substantially astride the ski-boot vertical midplane, and is structured so as to selectively lock the cuff 102 with respect to the foot-case 101 in a predetermined downhill position, in which the cuff 102 is inclined forward with respect to the vertical by a given angle advantageously raging between 5 and 25.

[0027] In more detail, the cuff locking device 105 is structured so as to, selectively and alternatively: rigidly connect the cuff 102 to the foot-case 101 in the above-mentioned downhill position; or to completely unlock/release the cuff 102 from the foot-case 101 so as to allow the cuff 102 to freely swing back and forth on the foot-case 101 about the rotation axis A, while remaining on the ski-boot midplane.

[0028] With reference to FIG. 1, in particular, the foot-case 101 has a hollow structure substantially in the shape of an oblong basin, and is preferably mainly made of plastic and/or composite material.

[0029] In addition, the lower part of foot-case 101 preferably has a lugged profile so as to grip on snow and/or ice, and therefore allow the user to walk on snow and ice in relative safety.

[0030] Preferably, the lower part of foot-case 101 is furthermore structured so as to couple/fasten in a stable, though easy releasable manner, to a ski binding device, or rather to a mountaineering or Telemark ski binding device, which in turn is stably fixed on the back of a generic downhill ski or similar.

[0031] In more detail, the lower part of the foot-case 101 is provided with a front toe 106, which is preferably structured so as to couple/fasten in a stable, though easy releasable manner, to the toe piece (not shown) of a ski binding device, or rather of a mountaineering or Telemark ski binding device, which in turn is stably fixed on the back of a generic downhill ski or similar; and of a rear heel 107, which is instead preferably structured so as to couple/fasten in a stable, though easy releasable manner, to the heel piece (not shown) of a ski binding device, or rather of a mountaineering or Telemark ski binding device, which in turn is stably fixed on the back of a generic downhill ski or similar.

[0032] With reference to FIG. 1, in particular the foot-case 101 preferably comprises: a substantially rigid shell 108, which is preferably made of plastic and/or composite material and is shaped substantially like an oblong basin so as to accommodate/contain the user's foot, advantageously roughly up to the height of the ankle; and preferably also a sole 109 made of vulcanised rubber or other elastomeric material with a high friction coefficient, which preferably has a lugged profile, and is securely fixed to the bottom wall of the shell 108 preferably by gluing.

[0033] In addition, the foot-case 101 preferably furthermore comprises a rigid front insert 110 and optionally also a rigid rear insert (not shown in the figure).

[0034] The rigid front insert 110 is preferably made of metallic material, and is stably embedded/incorporated in the bottom wall of shell 108 roughly at the toe 106 of the foot-case 101. The rigid front insert 110, in addition, is preferably structured so as to surface/emerge outside of shell 108 from opposite sides of the front toe 106 of foot-case 101, advantageously in a substantially specular position with respect to the ski-boot vertical midplane, so as to be able to couple/fasten in known manner with the toe piece (not shown) of the mountaineering ski binding device.

[0035] The rigid rear insert, on the other hand, is preferably made of metallic material, and is recessed in the shell 108 at the heel 107 so as to surface/emerge outside of the shell 108 and to couple/fasten in known manner with the heel piece (not shown) of the same mountaineering ski binding device.

[0036] With reference to FIG. 1, similarly to the foot-case 101, also the cuff 102 is preferably mainly made of plastic and/or composite material.

[0037] In more detail, the cuff 102 preferably comprises a concave and oblong supporting body 111, substantially rigid and preferably made of plastic and/or composite material, which is advantageously shaped substantially like a saddle or semi-tube so as to cover the rear part of the user's leg, from the ankle substantially up to the height of the calf, and ends inferiorly in a fork-like structure adapted to embrace the top of foot-case 101.

[0038] Moreover, the upper part of supporting body 111 is preferably provided with two substantially loboid-shaped, protruding flaps 111a which extend forwards from opposite sides of the ski-boot midplane and are bent one towards the other, so as to embrace the user's leg roughly at the height of the calf and form a substantially tubular structure, which surrounds the user's leg more or less at the height of the calf.

[0039] Moreover, the lower part of the cuff 102, or rather of supporting body 111, is preferably hinged to the foot-case 101, or rather to the shell 108, via two connecting hinges 112 preferably made of metallic material, which are arranged on the inner and outer lateral sides of foot-case 101 and cuff 102, aligned along the transversal axis A.

[0040] With reference to FIG. 1, the protective inner-boot 103, in turn, is preferably inserted within the foot-case 101 and advantageously also the cuff 102 in a manually removable/extractable manner.

[0041] In more detail, the protective inner-boot 103 is preferably shaped substantially like a boot and is preferably dimensioned so as to accommodate and protect the foot and the lower part of the user's leg, advantageously roughly up to the top of the cuff 102.

[0042] The ski-boot closing means, on the other hand, preferably include one or more manually-operated mechanical tightening devices, which are placed on the foot-case 101 and/or on the cuff 102, astride two opposite and facing flaps of the foot-case 101 or of the cuff 102, and are structured so as to selectively pull one towards the other and then lock said opposite flaps in the new position, so as to locally tighten the foot-case 101 or the cuff 102, thus immobilising the corresponding portion of the user's foot or leg stably inside the protective inner-boot 103.

[0043] In more detail, the ski-boot closing means preferably comprise a foot-case tightening assembly 113 and a cuff tightening assembly 114, advantageously both manually-operated.

[0044] The foot-case tightening assembly 113 is preferably located on the anterosuperior part of the foot-case 101, advantageously astride the longitudinal slit (not visible in the figures) that allows to elastically widen the area of the foot-case 101, or rather of shell 108, overlying the instep to facilitate the insertion of the foot inside the inner-boot 103, and is adapted to close/tighten the upper part of the foot-case 101, or rather of shell 108, on the user's foot, so as to immobilise the user's foot inside the foot-case 101, or rather inside the inner-boot 103.

[0045] The cuff tightening assembly 114, on the other hand, is located on the cuff 102 and is structured so as to selectively close/tighten at least the upper part of the cuff 102, or rather the upper part of supporting body 111, on the user's leg, in order to immobilise the user's leg inside the cuff 102, or rather inside the inner-boot 103.

[0046] In the example shown, in particular, the cuff tightening assembly 114 preferably includes a lever-closing buckle, which extends as a bridge between the two facing flaps of the cuff 102, or rather between the two front protruding flaps 111a of supporting body 111, and is selectively adapted to pull said facing flaps of cuff 102 one towards the other and then lock them in the new position, so as to tighten the upper part of the cuff 102 on the user's leg and thus immobilise the calf area inside the cuff 102, or rather inside the inner-boot 103.

[0047] In addition, the ski-boot closing means preferably also comprise a heel locking assembly 116, which is arranged astride the foot-case 101 and the cuff 102, and is adapted to bring and hold the heel of the user's foot in abutment on the rear part of the foot-case 101, or rather on the rear part of protective inner-boot 103.

[0048] In the example shown, in particular, the heel locking assembly 115 preferably comprises: a ratchet tightening device, which is located on the outer lateral side of the cuff 102, close to or at the hinge 112; and a transversal band with a flexible and substantially inextensible structure, which is butt-fixed on the inner lateral side of the cuff 102, close to or at the hinge 112, and extends grazing the upper part of foot-case 101, or rather grazing the part of the foot-case 101 that covers the user's instep, up to reach and engage in the ratchet tightening device.

[0049] The cuff locking device 105, the foot-case tightening assembly 113, the cuff tightening assembly 114 and the heel locking assembly 115 are components already known and readily available on the market, thus they won't be further described.

[0050] With reference to FIG. 1, the tightening strap 1 is adapted to be fitted/arranged on the cuff 102 so as to surround the cuff 102, and is adapted to close/tighten the cuff 102 on the user's leg in addition to the cuff tightening assembly 114.

[0051] In more detail, the tightening strap 1 is adapted to be wound in a loop around the cuff 102, or rather the upper part of the cuff 102, and then tightened around the cuff 102 by the user of the ski boot 100.

[0052] Advantageously, the ski-boot closing means therefore also include the tightening strap 1.

[0053] Preferably, the tightening strap 1 moreover has a manually adjustable length, so as to allow the user to adapt the length of the loop formed by the tightening strap 1 around the cuff 102, and thus the tightening on the upper part of the cuff 102, to the morphology of his/her own leg and calf.

[0054] In addition, the tightening strap 1 is preferably fitted/fixed on the cuff 102 of the ski boot 100 in an easily removable manner.

[0055] In the example shown, in particular, the cuff 102 is preferably provided with at least one oblong-shaped slot or loop 116, which extends more or less vertically along the rear part of the cuff 102, advantageously substantially astride the ski-boot vertical midplane, and the tightening strap 1 is threaded in pass-through and free slidable manner in said oblong slot or loop 116.

[0056] With reference to FIGS. 1, 2, 3 and 4, in addition, the tightening strap 1 moreover has longitudinally elastically-stretchable structure, so as to close/tighten the cuff 102, or rather the upper part of the cuff 102, in an elastic manner on the user's calf.

[0057] The tightening strap 1 in particular comprises: an oblong flexible element 2, advantageously with a substantially ribbonlike structure, which is adapted to be wound around the cuff 102, preferably at the top thereof; and advantageously also a manually-operated fastening device 3, which is adapted to selectively connect the two opposite ends or end portions of the oblong flexible element 2 one to the other in a firm and stable, but easy releasable manner.

[0058] In more detail, the oblong flexible element 2 preferably has an overall length such that it can be completely wound around the cuff 102, advantageously at the top of the latter, and includes at least one elastic member with auxetic behaviour, which is capable to stretch and at the same time also to widen in elastic manner when the oblong flexible element 2 is longitudinally subjected to traction.

[0059] Moreover, this elastic member with auxetic behaviour consists of or in any case includes an oblong and advantageously also elastically flexible plate-like body 4, which has a monolithic structure and is divided into a plurality of contiguous flat sectors, each of which takes up the entire thickness of the plate-like body 4 and has a macroscopic reticular structure with auxetic behaviour, which structure is capable to stretch and at the same time also to widen in elastic manner when the plate-like body 4 is subjected to traction in the longitudinal direction, and furthermore differs from that of the adjacent flat sectors advantageously in shape and/or dimensions.

[0060] Advantageously, the macroscopic reticular structure with auxetic behaviour of each flat sector is moreover a two-dimensional reticular structure with auxetic behaviour, so that each flat sector of the elastic plate-like body 4 can stretch and widen only parallel to its own laying plane.

[0061] In this way, the auxetic behaviour of the elastic plate-like body 4 varies from flat sector to flat sector, and allows the entire elastic plate-like body 4 to deform in a programmed manner when it is longitudinally subjected to traction.

[0062] Preferably the elastic plate-like body 4 is furthermore structured so as to allow a maximum increase in the length of the oblong flexible element 2 of less than or equal to 40 mm millimetres.

[0063] With reference to FIGS. 1, 2, 3 and 4, the fastening device 3, on the other hand, is preferably stably located at a first end or end portion of the oblong flexible element 2, and is structured so as to connect in a stable, though easy releasable manner, to a second end or end portion of the same oblong flexible element 2, opposite to said first end.

[0064] In more detail, the fastening device 3 is preferably fixed on said first end or end portion of the oblong flexible element 2 in a manually adjustable manner, and is preferably structured so as to connect in a stable, though easy releasable manner, to the second end of the same oblong flexible element 2.

[0065] In other words, the fastening device 3 is preferably fixed or fixable on the first end or end portion of the oblong flexible element 2 in a multitude of possible and freely selectable positions, so as to allow the user to vary as desired the overall length of the loop formed by the tightening strap 1 around the cuff 102.

[0066] With reference to FIGS. 2, 3 and 4, in particular the oblong flexible element 2 is preferably longitudinally divided into at least two consecutive segments, one substantially inextensible and the other elastically stretchable, and the elastically stretchable segment incorporates the elastic plate-like body 4 with auxetic behaviour.

[0067] In more detail, the oblong flexible element 2 is preferably provided with at least a first segment 2a which has a flexible and substantially inextensible structure, and with at least a second segment 2b, preferably contiguous and complementary to the flexible segment 2a, which instead incorporates said elastic plate-like body 4 with auxetic behaviour, and advantageously also has an elastically flexible structure.

[0068] Preferably, the tightening strap 1 is adapted to be fitted on the cuff 102, or rather on the top of the cuff 102, so that the inextensible segment 2a of the oblong flexible element 2 extends grazing the rear part of the cuff 102 and, advantageously, can moreover engage the slot or loop 116 of the same cuff 102 in a pass-through and free slidable manner; and that the stretchable segment 2b of the oblong flexible element 2 instead extends grazing the front part of the cuff 102, or rather grazing the two front protruding flaps 111a of the supporting body 111.

[0069] With reference to FIGS. 2, 3 and 4, in particular, the inextensible segment 2a of the oblong flexible element 2 preferably includes a strip of flexible and inextensible material 5, such as a Cordura webbing or other high-strength fabric, which has a nominal width advantageously ranging between 1 and 5 cm (centimetres) and a nominal length advantageously ranging between 5 and 60 cm (centimetres).

[0070] Preferably, the proximal end of the strip of flexible and inextensible material 5 is moreover unmovably fixed to a corresponding end of the stretchable segment 2b advantageously by means of stitching and/or gluing.

[0071] The stretchable segment 2b of the oblong flexible element 2, on the other hand, is preferably longitudinally divided into a central section incorporating the elastic plate-like body 4 with auxetic behaviour, and into two lateral sections, advantageously substantially inextensible, which are arranged on opposite sides of the central section and are structured so as to transfer the tensile stresses to the central section.

[0072] A first lateral section of the stretchable segment 2b is preferably structured so as to connect in a stable, though easy releasable manner, to the fastening device 3.

[0073] The second lateral section of the stretchable segment 2b, on the other hand, is preferably fixed, advantageously in an unmovable manner, to the inextensible segment 2a of the oblong flexible element 2, or rather to the proximal end of the strip of inextensible material 5.

[0074] Preferably one or both of the lateral sections of the stretchable segment 2b are furthermore structured so as to channel/direct the tensile stresses only in a series of prefixed and limited points of the central section of the stretchable segment 2b.

[0075] With reference to FIGS. 1, 3 and 4, in the example shown, in particular, the stretchable segment 2b of oblong flexible element 2 preferably has a monolithic plate-like structure.

[0076] In other words, the stretchable segment 2b preferably consists of a single oblong and flexible plate-like element 6, which is preferably made of plastic material advanta-geously via injection moulding, and includes the elastic plate-like body 4 of the tightening strap 1.

[0077] In more detail, the oblong plate-like element 6 is preferably longitudinally divided into a central section 7 and into two opposite lateral sections 8, which seamlessly join to the central section 7, on opposite sides thereof.

[0078] The central section 7 of the oblong plate-like element 6 forms the elastic plate-like body 4.

[0079] One or both of the lateral sections 8 of the oblong plate-like element 6, on the other hand, are preferably structured so as to channel/direct the tensile stresses in prefixed and limited points of the central section 7 of the oblong plate-like element 6.

[0080] In more detail, the central section 7 of the oblong plate-like element 6 is preferably divided into a plurality of contiguous flat sectors 7a, each of which has a macroscopic reticular structure, advantageously two-dimensional, which is capable of stretching and, at the same time, also of widening in elastic manner when the oblong plate-like element 6 is subjected to traction in the longitudinal direction, and also differs from that of the immediately adjacent flat sectors 7a advantageously in shape and/or dimensions.

[0081] Even more specifically, the central section 7 of oblong plate-like element 6 preferably has, within each flat sector 7a, a series of through openings of a prefixed shape, which are arranged adjacent to one another according to a prefixed regular geometric pattern, so as to form a two-dimensional reticular structure with auxetic behaviour.

[0082] In other words, these through openings are preferably shaped so as to form, within the flat sector 7a, a series of nodes that are connected to one another by links or oblong branches of arcuate shape, which straighten out when the oblong plate-like element 6 is subjected to traction in the longitudinal direction.

[0083] Clearly, shape and dimensions of the through openings vary from one flat sector 7a to the other.

[0084] The lateral sections 8 of the oblong plate-like element 6, in turn, are preferably substantially inextensible, and preferably contribute to forming a respective free end of the plate-like element 6 and of the stretchable segment 2b.

[0085] In more detail, a first lateral section 8 of the oblong plate-like element 6 is preferably structured so as to connect in a stable, though easy releasable manner, to the fastening device 3.

[0086] The second lateral section 8 of the oblong plate-like element 6, on the other hand, is preferably unmovably butt-fixed to the inextensible segment 2a of the oblong flexible element 2, or rather to the proximal end of the strip of inextensible material 5, advantageously by means of stitching and/or gluing.

[0087] With reference to FIGS. 2, 3 and 4, moreover, at least one or, more conveniently, both of the lateral sections 8 of the oblong plate-like element 6 preferably have a sunburst-like structure converging towards the respective free end of the oblong plate-like element 6, so as to channel the tensile stresses in prefixed areas of the junction with the central section 7 of the oblong plate-like element 6.

[0088] In more detail, the/each lateral section 8 of the oblong plate-like element 6 preferably comprises a plurality of separate and distinct and substantially inextensible longitudinal tie-rods 9 (three tie-rods in the example shown), which branch out from respective junction points located on the lateral edge of the central section 7, and extend cantilevered towards the corresponding free end of the oblong plate-like element 6, advantageously converging towards one another so as to join one another close to the free end of the oblong plate-like element 6.

[0089] In the example shown, in particular, the oblong plate-like element 6 has a nominal thickness preferably ranging between 1 and 6 mm (millimetres), has a nominal length preferably ranging between 10 and 30 cm (centimetres) and/or has a nominal width preferably ranging between 3 and 6 cm (centimetres).

[0090] Preferably, the oblong plate-like element 6 is moreover made of polyurethane TPU or other elastomer, preferably of the thermoplastic type.

[0091] With reference to FIGS. 1, 2, 3 and 4, the fastening device 3, on the other hand, preferably includes a buckle 10 advantageously made of metallic material, which is fixed in a manually adjustable manner on an end portion of the inextensible segment 2a of the oblong flexible element 2, or rather of the strip of inextensible material 5, and is preferably provided with a protruding appendage 10a substantially in the shape of an oblong hook, which is adapted to engage in a stable, but releasable manner, a tubular eyelet 11 located on the corresponding free end of the stretchable segment 2b of the oblong flexible element 2.

[0092] In more detail, in the example shown the fastening buckle 10 is preferably centrally provided with a pair of adjacent rectilinear slits, which are engaged in a pass-through and free slidable manner by a distal portion of the strip of inextensible material 5, which, in turn, is preferably kept folded back on itself by a Hook-and-loop locking system 12.

[0093] Operation of tightening strap 1 and of ski boot 100 are easily inferable from the above, and do not require further explanation.

[0094] The advantages connected to the particular structure of the elastic member with auxetic behaviour, or rather of the elastic plate-like body 4, are remarkable.

[0095] Being provided with a plurality of contiguous flat sectors 7a each having a reticular structure with auxetic behaviour, advantageously two-dimensional and different from that of the adjacent flat sectors 7a, in addition to widening when subjected to traction, the elastic plate-like body 4, or rather the central section 7 of the oblong plate-like element 6, is capable of freely twisting during stretching, thus locally adapting to the profile of the front part of the cuff 102.

[0096] In this way, the pressure stresses are distributed substantially uniformly over the entire contact area with the cuff 102, improving the tightening and the fitting comfort.

[0097] In addition, the lateral sections of the stretchable segment 2b of the oblong flexible element 2, or rather the lateral sections 8 of the oblong plate-like element 6, allow to channel the tensile stresses into prefixed and limited points of the elastic plate-like body 4, or rather of the central section 7 of oblong plate-like element 6, thus optimising the tensile response of each single area of the same elastic plate-like body 4.

[0098] Lastly, it is clear that modifications and variations may be made to the tightening strap 1 and the ski boot 100 without thereby departing from the scope of the present invention.

[0099] For example, in a different embodiment, the fastening device 3 of tightening strap 1 may comprise a manually-operated self-locking buckle or the like.