WO2015094081A1

WO2015094081A1 - Ski and method for manufacturing a ski

Info

Publication number: WO2015094081A1
Application number: PCT/SE2014/051376
Authority: WO
Inventors: Max Krogager
Original assignee: Inadco Ab
Priority date: 2013-12-16
Filing date: 2014-11-19
Publication date: 2015-06-25

Abstract

The present disclosure relates to a ski (10), particularly a cross-country ski, and methods of manufacture therefor. The ski (10) comprises a rear section (12), a middle section (13) and a front section (14).The middle section (13) is shear flexible and arranged to shear deform in an essentially vertical direction in response to a pressure applied over one of said rear section (12), as is typical during the glide phase,and said front section (14), as is typical during the drive phase, when the ski (10) is arranged on a plane (18) supporting the ski (10).

Description

Ski and method for manufacturing a ski

TECHNICAL FIELD

The present disclosure relates to a ski, particularly a cross-country ski, and methods of manufacture therefor. BACKGROUND

A conventional cross-country ski functions as a thin and rigid beam, with a slight curvature. When with about half the skier's body weight, the cross-country ski will, when being placed on a flat snow surface, have its two end surfaces, where both ends typically exhibit low friction when gliding across a snow surface, in contact with the flat snow surface and the surface about the apex of the curvature will be lifted slightly off the flat snow surface, with a typical height of about 0.5 mm. The two end surfaces are so arranged to typically exhibit low friction when brought in contact with a snow surface. The surface about the apex of the curvature will typically be so arranged to exhibit high friction when brought in contact with a snow surface. When skiing, two distinct phases relating to the movement of the cross-country ski across a snow surface can be discerned; a glide phase and a drive phase. During the glide phase, the cross-country ski ideally retains its curvature, such that only the end surfaces with low friction is in contact with the snow surface and the ski glides across the snow surface with minimal frictional losses. During the drive phase, the skier pushes down strongly about the apex of the curvature to cause the cross-country ski to bend so that the high friction surface is brought in contact with the snow surface. The temporary increase in friction allows the skier to direct some of the applied pressure along the longitudinal direction of the cross-country ski, thereby propelling the skier forward in the longitudinal direction of the cross-country ski. The rigidity and the curvature of the cross-country ski are important factors for determining the properties of the cross-country ski. If the cross-country ski is very rigid and/or the curvature is such that the high friction surface is raised significantly off the snow surface, the pressure necessary to bring the high friction surface in contact with the snow surface will be high, but such an embodiment of a cross country ski will typically exhibit good glide properties. On the other hand, if the cross-country ski exhibits a low stiffness and/or the curvature is such that the high friction surface is very close to the snow surface, the pressure necessary to bring the high friction surface in contact with the snow surface will be low, but such an embodiment of a cross-country ski will typically experience higher friction as the high friction surface will often be in partial contact with the snow. Thus, embodiments of cross-country skis exhibit a tradeoff between a higher stiffness and better glide, but requiring a higher pressure to bring the high friction surface in contact with the snow surface, and a lower stiffness but poorer glide, since the latter will mean that the high friction surface will experience more unwanted contact with the snow surface. The selection of cross-country skis therefore often has to be made so that the stiffness matches the weight of the intended user.

SE454138 B addresses the compromise between having a good glide during the glide phase and experiencing high friction during the drive phase. Said patent relates to a cross-country ski, where a lower band, running along the longitudinal direction of whole the cross-country ski, is divided into three parts, each part being joined with the subsequent part by a viscoelastic member. When a significant pressure is applied during the drive phase, the outer parts of the divided band is pulled in opposite directions as the ski bends, which in turn causes the viscoelastic members to deform and subsequently press down the middle part of the divided band, thereby pressing down the high friction surface towards a snow surface.

SUMMARY

The present disclosure presents skis, particularly cross-country skis, and methods of manufacturing skis that exhibit a low effective friction during the glide phase while

simultaneously improving the efficiency of the applied pressure during the drive phase.

The solution proposes that the ski comprises a rear section, a middle section and a front section. The middle section is shear flexible and arranged to shear deform in an essentially vertical direction in response to a pressure applied over one of said rear section and said front section, when the ski is arranged on a plane supporting the ski. An advantage of this solution is that the shear flexible middle section will be deformed depending on where pressure is applied, which in turn alters a curvature of the ski. By introducing the shear flexible middle section, the relation of the sections of the ski and the supportive plane is affected by applying a pressure over either the rear section or the front section of the ski. This also means that less pressure typically needs to be applied over either the front section or the rear section, compared to a prior art ski, to bring the front section or the rear section down towards the supportive plane. A further advantage of this is that the ski can be arranged to, during the glide phase, when a skier typically transfers the bodyweight to press down over a part of the rear section adjacent to the middle section, raise a part of the front section adjacent to the middle section significantly higher above the supportive plane compared to a prior art ski, which reduces the effective friction of the ski during the glide phase.

According to an aspect of the disclosure, the front section comprises a high friction zone. The high friction zone is arranged essentially adjacent to the middle section.

A high friction zone may be pressed against an underlying surface during the drive phase. This increases the friction between the ski and the underlying surface. This, in turn, leads to a more efficient drive phase.

According to an aspect of the disclosure, the rear section comprises a rear pressure zone and the front section comprises a front pressure zone. The rear pressure zone and the front pressure zone are arranged adjacent to the middle section. The middle section is arranged to shear deform in an essentially vertical direction in response to a pressure applied over one of said rear pressure zone and said front pressure zone, when the ski is arranged on a plane supporting the ski.

By introducing well-defined pressure zones, the ski can be arranged to fit typical gender and weight properties of intended users. The dimensions and shear flexible properties of the middle section can be arranged during manufacturing to accommodate e.g. different foot sizes and/or weight ranges.

According to an aspect of the disclosure, the middle section is further arranged to, in response to a first pressure applied over the rear pressure zone and a second pressure applied over the front pressure zone, essentially maintain its overall shape, when the first and second pressure are essentially equal and the ski is arranged on a plane supporting the ski.

By arranging the middle section to essentially maintain its overall shape when two essentially equal pressures are applied of the rear and front pressure zones, respectively, when the ski is arranged on a plane supporting the ski, the ski can be arranged to maintain an overall curvature during the glide phase, where the overall curvature is significantly greater than that of a prior art ski. In particular, a high friction zone under the front section arranged essentially adjacent to the middle section, can be raised significantly above the supportive plane during the glide phase. This has the advantage of reducing the friction during the glide phase. According to an aspect of the disclosure, at least one recess is formed in the middle section.

By forming at least one recess in the middle section the ski can be made lighter. A further advantage is that shear flexible elements may be introduced in the recess to adjust the shear flexible properties of the ski.

According to an aspect of the disclosure, said at least one recess is a plurality of quadrangular recesses arranged in parallel along the longitudinal direction of the ski.

By forming a plurality of quadrangular recesses arranged in parallel along the longitudinal direction of the ski in the middle section, the shear flexible properties can be adjusted during manufacture by varying the number of quadrangular recesses and their shapes. The walls between the quadrangular recessess may be the core material of the ski or substituted by walls with other mechanical properties, thereby further modifying the shear flexible properties.

According to an aspect of the disclosure, said at least one recess is filled with foam material.

An advantage of this is that the foam material is shear flexible, thereby contributing to the shear flexible properties of the middle section. According to an aspect of the disclosure, the ski has an overall curvature, that, when the ski is unloaded, raises the high friction zone a predetermined distance from the plane on which the ski is supported.

By introducing an overall curvature of an unloaded ski that raises the high friction zone a predetermined distance from the supporting plane, the relation between the high friction zone and the supporting plane during the glide phase can be adjusted.

According to further aspect of the disclosure, the predetermined distance is in the interval 3- 50 mm, typically 20-45 mm. This means that when the ski is loaded with half the skier's bodyweight during the glide phase, the high friction zone will typically be lifted 2-20 mm above an underlying snow surface. This is advantageous since it reduces the probability that the high friction zone will come in contact with the underlying snow surface during the glide phase. According to an aspect of the disclosure, the ski is further arranged to, in response to a pressure applied in an essentially vertical direction over the rear pressure zone, when the ski is arranged on a plane supporting the ski, exhibit an angle between the overall curvature of the rear section and the plane, such that air is pressed in under the rear section during forward movement of the ski across the supporting plane. According to a further aspect of the disclosure, the angle falls in the range 0.085°-1.72°.

An advantage of having air pressed in under the rear section during forward movement is that it lowers the friction between the rear friction zone and the supporting plane. For many embodiments, an angle in the range 0.085°-1.72° will provide optimal intake of air underneath the rear section in order to reduce the friction during the glide phase. The present disclosure further relates to a method for manufacturing a ski, particularly a cross-country ski. The ski comprises a rear section, a middle section and a front section. The middle section is shear flexible and arranged to shear deform in an essentially vertical direction in response to a pressure applied over one of said rear section and said front section, when the ski is arranged on a plane supporting the ski. The method comprises arranging the rear section adjacent to the middle section and arranging the front section adjacent to the middle section.

The method has the advantage that it manufactures a ski according to the present disclosure.

According to an aspect of the disclosure, a method for manufacturing a ski comprises a step of providing a surface with a predetermined surface flatness. The method further comprises arranging a ski base on the surface. The method further comprises applying liquid filler on the ski base. The method further comprises arranging the ski on the applied liquid filler. The method further comprises applying a pressure over the rear section of the ski arranged on the applied liquid filler. The method further comprises curing the liquid filler while maintaining the applied pressure. The method has the advantage of evening out the surface of the ski intended to come in contact with the snow, as the surface of the ski appears during load.

According to an aspect of the disclosure, the liquid filler is a plaster.

Plaster offers cheap and easy handling, while also acting as a glue. A further advantage is that if the ski base has to be replaced, the plaster can be reheated to turn liquid and the ski base can be easily removed and replaced according to the steps of the method of the disclosure.

According to an aspect of the disclosure, the method further comprises a step of forming a convolution on the surface. The convolution forms an angle corresponding to the angle according to claim 10 or 11 of the present disclosure.

According to a further aspect of the disclosure, the step of arranging the ski on the applied liquid filler comprises arranging the ski, such that the convolution is arranged under the ski, such that the step of curing the liquid filler while maintaining the applied pressure results in that the ski in response to a pressure applied in an essentially vertical direction over the rear pressure zone, when the ski is arranged on a plane supporting the ski, exhibit an angle between the overall curvature of the rear section and the plane, such that air is pressed in under the rear section during forward movement of the ski across the supporting plane. By forming a convolution on the surface, it is possible to shape how the ski shall behave under different types of loads. By having the convolution form an angle and arranging the ski according to the aspect above, the ski can be manufactured so that it exhibits the same angle during the glide phase.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure la shows a cross section view of an unloaded ski according to one embodiment of the invention;

Figure lb shows a cross section view of a ski according to one embodiment of the invention, where a pressure is applied over the rear pressure zone;

Figure lc shows a cross section view of a ski according to one embodiment of the invention, where essentially equal pressures are applied over the rear pressure zone and the front pressure zone; Figure Id shows a cross section view of a ski according to one embodiment of the invention, where a pressure is applied over the front pressure zone;

Figure 2a shows a flowchart of an embodiment of a method for manufacturing a ski according to the disclosure; Figure 2b shows a cross section view and a flowchart of an embodiment of a further method for manufacturing a ski according to the disclosure.

DETAILED DESCRIPTION

Figure la shows a cross section view of an unloaded ski 10. The ski comprises a rear section 12, a middle section 13 and a front section 14. The middle section 13 is shear flexible and arranged to shear deform in an essentially vertical direction in response to a pressure applied over one of said rear section 12 and said front section 14, when the ski 10 is arranged on a plane 18 supporting the ski 10. The front section 14 comprises a high friction zone 15. The high friction zone 15 is arranged essentially adjacent to the middle section 13. The rear section 12 comprises a rear pressure zone 16 and the front section 14 comprises a front pressure zone 17. The rear pressure zone 16 and the front pressure zone 17 are arranged adjacent to the middle section 13. The middle section 13 comprises a plurality of recesses in the form of a plurality of rectangular recesses which are arranged in parallel along the longitudinal direction of the ski 10. The ski 10 has an overall curvature, that, when the ski 10 is unloaded, raises the high friction zone 15 a predetermined distance d from the plane 18 on which the ski 10 is supported.

Figure lb shows a cross section view of a ski 10, as discussed in Figure la, where a pressure Fll is applied over the rear pressure zone 16. The ski 10 is further arranged to, in response to a pressure Fll applied in an essentially vertical direction over the rear pressure zone 16, when the ski 10 is arranged on a plane 18 supporting the ski 10, exhibit an angle a between the overall curvature of the rear section 12 and the plane 18, such that air is pressed in under the rear section 12 during forward movement of the ski 10 across the supporting plane 18.

Figure lc shows a cross section view of a ski 10, as discussed in Figure la, where essentially equal pressures F12, F13 are applied over the rear pressure zone 16 and the front pressure zone 17. The middle section 13 is further arranged to, in response to a first pressure F12 applied over the rear pressure zone 16 and a second pressure F13 applied over the front pressure zone 17, essentially maintain its overall shape, when the first F12 and second pressure F13 are essentially equal and the ski 10 is arranged on a plane 18 supporting the ski 10. Figure Id shows a cross section view of a ski 10, as discussed in Figure la, where a pressure F14 is applied over the front pressure zone 17. The resulting shear deformation has pressed the high friction zone 15 in contact with the supporting plane 18.

In some embodiments the rear pressure zone 16, the middle section 13 and the front pressure zone 17 are dimensioned based on typical foot sizes of an intended user. In some

embodiments, the rear pressure zone 16 extends in the range 30-60 mm along the

longitudinal direction of the ski 10. In some embodiments, the front pressure zone extends in the range 80-120 mm along the longitudinal direction of the ski 10. In some embodiments, a means for attaching a ski boot is arranged in an area of the front pressure zone opposite to the middle section 13. In some embodiments, the middle section extends in the range 80-150 mm along the longitudinal direction of the ski 10.

In some embodiments of the disclosure, the predetermined distance d is in the interval 3-50 mm, typically 20-45 mm.

In some embodiments of the disclosure, a distance between the high friction zone 15 and the supporting plane 18 falls in the range 2-20 mm, when the total pressure on the ski equals about the skiers half body weight and the pressure is applied as shown in Figure lb or Figure lc, which is typical for the glide phase. For a prior art ski, a typical distance between the snow surface and a high friction zone of the prior art ski is about 0.5 mm during the glide phase. This means that small changes in pressure or irregularities in the snow will bring the high friction zone of the prior art ski in contact with the snow and increase the friction. In embodiments of the disclosure where the distance between the high friction zone 15 and the supporting plane 18 falls in the range 2-20 mm during the glide phase, the negative effects exhibited by a prior art ski can be significantly reduced.

In some embodiments of the disclosure, the angle a falls in the range 0.085°-1.72°.

During the glide phase, the skier shifts his weight backwards. By shifting the weight

backwards, pressure is taken of the front section 14, where a high friction zone 15 is typically located. When pressure Fll is applied over the rear pressure zone 16, the resulting shear deformation will press the rear section 16 down towards the supporting plane 18. In embodiments having a curvature during the glide phase, as in the examples shown in Figures lb and lc, the angle a will be exhibited between the rear section 12 of the ski 10 and the supporting plane 18. As the skier shifts the weight backwards, the resulting compression of the rear section 12 towards the supporting plane 18 will push against the air in between the rear section 12 and the supporting plane 18. If the angle a is too great, air will be pushed in front of the opening between the rear section 12 and the supporting plane 18 formed by the angle a. If the angle a is too small, air will not effectively enter in between the rear section 12 and the supporting plane 18. As a consequence, if the angle a is too great or too small, no effective friction reduction by reducing the amount of contact between the rear section 12 and the supporting plane 18 will be provided.

In some embodiments, the at least one recess is a single recess.

In some embodiments, the at least one recess is filled with foam material.

In some embodiments, the ski 10 comprises at least one ski base 19a, 19b. In some embodiments, one ski base 19a extends under the rear section 12 and the middle section 13. In further embodiments, the ski base 19a extends under the whole of the rear section 12 and the middle section 13. In some embodiments, one ski base extends 19b under the front section 14. In further embodiments, the ski base 19b extends under the whole of the front section 14. In some embodiments where the front section 14 comprises a high friction zone 15, the front section 14 comprises a ski base 19b extending from the high friction zone 15 to the end of the front section 14. In one example, said at least one ski base 19a, 19b comprises a low friction material. In yet one example, said at least one ski base 19a, 19b is coated with a low friction material. In some embodiments, said at least one ski base 19a, 19b comprises polyethene.

In some embodiments, the rear section 12 comprises at least one of a glass fiber plastic material, a carbon fiber plastic material and a wood material.

In some embodiments, the plurality of quadrangular recesses of the at least one recess comprises one or more rectangular recesses. In some embodiments, the plurality of rectangular recesses comprises rounded corners. In some embodiments, the plurality of quadrangular recesses of the at least one recess comprises one or more rhomboidal recess.

In some embodiments, the plurality of quadrangular recesses of the at least one recess comprises one or more parallelogram recesses. In some embodiments, the plurality of quadrangular recesses of the at least one recess comprises one or more trapezoidal recesses.

In some embodiments, the middle section 13 comprises at least one of a glass fiber plastic material, a carbon fiber plastic material and a wood material. In particular, in some embodiments where the at least one recess comprises a plurality of rectangular recesses arranged in parallel along the longitudinal direction of the ski 10, the walls between the rectangular recesses, as well as the top and bottom above and below the rectangular recesses, comprise a glass fiber plastic material.

In some embodiments, the front section 14 comprises at least one of a glass fiber plastic material, a carbon fiber plastic material and a wood material. In some embodiments having a high friction zone 15, the high friction zone 15 comprises at least one of grip wax, mohair, sand and epoxy, and an epoxy surface of high surface roughness.

In one example of an embodiment having a high friction zone 15, the high friction zone 15 has an extension in the longitudinal direction of the ski 10 falling in the range of 200-460 mm. Figures 2a and 2b shows flowcharts of methods 100, 300 for manufacturing a ski. The ski 200 comprises a rear section 202, a middle section 203 and a front section. The middle section 203 is shear flexible and arranged to shear deform in an essentially vertical direction in response to a pressure F21 applied over one of said rear section 202 and said front section, when the ski 200 is arranged on a plane 209 supporting the ski 200. In Figure 2a, the method 100 comprises arranging S21 the rear section 202 adjacent to the middle section 203 and arranging S22 the front section adjacent to the middle section 203.

In some embodiments having a high friction zone, the step of arranging S22 the front section adjacent to the middle section 203 comprises arranging the high friction zone adjacent to the middle section 203. In Figure 2b a method 300 for manufacturing a ski 200 comprises a step of providing S23a a surface 209 with a predetermined surface flatness.

In some embodiments, the surface flatness of the provided S23a surface 209, when measured as a derived median plane falling inside a tolerance zone defined by the space between two parallel planes having a mutual distance defining a tolerance separation, the tolerance separation being less than or equal to 0.05 mm.

The method 300 further comprises a step of arranging S24 a ski base 212 on the surface 209.

The method 300 further comprises a step of applying S25 liquid filler 211 on the ski base 209.

The method 300 further comprises a step of arranging S26 the ski 200 on the applied liquid filler 211.

The method 300 further comprises a step of applying S27 a pressure F21 over the rear section 202 of the ski 200 arranged on the applied liquid filler 211.

The method 300 further comprises a step of curing S28 the liquid filler 211 while maintaining the applied pressure F21.

In some embodiments, the liquid filler is a plaster.

In some embodiments, the method 300 further comprises a step of forming 23b a convolution 210 on the surface 209, such that the convolution 210 forms an angle a corresponding to the angle a as discussed above. In one example, arranging S26 the ski 200 on the applied liquid filler 211 comprises arranging the ski 200, such that the convolution 210 is arranged under the ski 200, such that the step of curing S28 the liquid filler 211 while maintaining the applied pressure F21 results in that the ski 200 in response to a pressure F21 applied in an essentially vertical direction over the rear pressure zone 206, when the ski 200 is arranged on a plane 209 supporting the ski 200, exhibit an angle a between the overall curvature of the rear section 202 and the plane 209, such that air is pressed in under the rear section 202 during forward movement of the ski 200 across the supporting plane 209.

Claims

1. A ski (10; 200), particularly a cross-country ski, comprising a rear section (12; 202), a middle section (13; 203) and a front section (14), characterized in that the middle section (13; 203) is shear flexible and arranged to shear deform in an essentially vertical direction in response to a pressure (Fll, F14; F21) applied over one of said rear section (12; 202) and said front section (14), when the ski (10; 200) is arranged on a plane (18; 209) supporting the ski (10; 200).

2. The ski (10; 200) according to claim 1, wherein the front section (14) comprises a high friction zone (15), the high friction zone (15) being arranged essentially adjacent to the middle section (13; 203).

3. The ski (10; 200) according to claim 1 to 2, wherein the rear section (12; 202)

comprises a rear pressure zone (16; 206) and the front section (14) comprises a front pressure zone (17), the rear pressure zone (16; 206) and the front pressure zone (17) being arranged adjacent to the middle section (13; 203), the middle section (13; 203) being arranged to shear deform in an essentially vertical direction in response to a pressure (Fll, F14; F21) applied over one of said rear pressure zone (16; 206) and said front pressure zone (17), when the ski (10; 200) is arranged on a plane (18; 209) supporting the ski (10; 200).

4. The ski (10; 200) according to claim 3, wherein the middle section (13; 203) is further arranged to, in response to a first pressure (F12) applied over the rear pressure zone (16) and a second pressure (F13) applied over the front pressure zone (17), essentially maintain its overall shape, when the first (F12) and second pressure (F13) are essentially equal and the ski (10; 200) is arranged on a plane (18; 209) supporting the ski (10; 200).

5. The ski (10; 200) according to any of claims 1 to 4, wherein at least one recess is

formed in the middle section (13; 203).

6. The ski (10; 200) according to claim 5, wherein said at least one recess comprises a plurality of quadrangular recesses arranged in parallel along the longitudinal direction of the ski (10; 200).

7. The ski (10; 200) according to claim 5 or 6, wherein said at least one recess is filled with foam material.

8. The ski (10; 200) according to any of claims 1 to 7, wherein said ski (10; 200) has an overall curvature, which, when the ski (10; 200) is unloaded, is arranged to raise the high friction zone (15) a predetermined distance (d) from the plane (18; 209) on which the ski (10; 200) is supported.

9. The ski (10; 200) according to claim 8, wherein the predetermined distance (d) is in the interval 3-50 mm, typically 20-45 mm.

10. The ski (10; 200) according to any of claims 3-9, wherein the ski (10; 200) is further arranged to, in response to a pressure (Fll; F21) applied in an essentially vertical direction over the rear pressure zone (16; 206), when the ski (10; 200) is arranged on a plane (18; 209) supporting the ski (10; 200), exhibit an angle (a) between the overall curvature of the rear section (12; 202) and the plane (18; 209), such that air is pressed in under the rear section (12; 202) during forward movement of the ski (10; 202) across the supporting plane (18; 209).

11. The ski (10; 200) according to claim 10, wherein the angle (a) falls in the range 0.085°- 1.72°.

12. A method (100; 300) for manufacturing a ski (10; 200), particularly a cross-country ski, comprising a rear section (12; 202), a middle section (13; 203) and a front section (14), the middle section (13; 203) being shear flexible and arranged to shear deform in an essentially vertical direction in response to a pressure (Fll, F14; F21) applied over one of said rear section (12; 202) and said front section (14), when the ski (10; 200) is arranged on a plane (18; 209) supporting the ski (10; 200), the method (100; 300) comprising: arranging (S21) the rear section (12; 202) adjacent to the middle section (13; 203); arranging (S22) the front section (14) adjacent to the middle section (13; 203).

13. The method (100; 300) according to claim 12, the method (100; 300) further

comprising:

providing (S23a) a surface (209) with a predetermined surface flatness;

arranging (S24) a ski base (212) on the surface (209);

applying (S25) liquid filler (211) on the ski base (212);

arranging (S26) the ski (200) on the applied liquid filler (211);

applying (S27) a pressure (F21) over the rear section (202) of the ski (200) arranged on the applied liquid filler (211) and

curing (S28) the liquid filler (211) while maintaining the applied pressure (F21).

14. The method (100; 300) according to claim 13, wherein the liquid filler (211) is a plaster.

15. The method (100; 300) according to claim 13 or 14, wherein the method (100; 300) further comprises a step of forming (23b) a convolution (210) on the surface (209), such that the convolution (210) forms an angle (a) corresponding to the angle (a) according to claim 10 or 11.

16. The method (100; 300) according to claim 15, wherein arranging (S26) the ski (200) on the applied liquid filler (211) comprises arranging the ski (200), such that the convolution (210) is arranged under the ski (200), such that the step of curing (S28) the liquid filler (211) while maintaining the applied pressure (F21) results in that the ski (200) in response to a pressure (F21) applied in an essentially vertical direction over a rear pressure zone (206), when the ski (200) is arranged on a plane (209) supporting the ski (200), exhibit an angle (a) between the overall curvature of the rear section (202) and the plane (209), such that air is pressed in under the rear section (202) during forward movement of the ski (200) across the supporting plane (209).