Cross-Country Ski Sidecut for Double-Push Technique
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Solution Overview
Problem
The double-push technique in cross-country skiing is hindered by the need for an intermediate jump, which increases energy consumption and prevents overlapping leg impressions, as conventional cross-country skis lack the necessary curvature to replicate the S-shaped running line of inline skating.
Innovation Solution
A cross-country ski design with a sidecut and minimal camber, featuring a waist in the central area and varying ski widths and thicknesses to ensure a homogeneous load pressure distribution, allowing for an S-shaped running line without digging into the snow, achieved through curvature and material flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional cross-country ski design is used, then the ski runs straight ahead or slightly outwards, but the double-push technique cannot be performed without an intermediate jump
Solution Approach 1:
The patent applies a sidecut with a specific radius of curvature (10-30 meters) to the ski design, creating an S-shaped running line that enables the double-push technique. This curvature allows the ski to naturally follow the S-shaped path during ground contact, eliminating the need for intermediate jumps and enabling continuous overlapping leg impressions, thereby reducing energy consumption while improving ease of operation.
2Ease of operation
If a strong sidecut is fitted to enable curved driving line, then the double-push technique can be performed, but high pressure points are created causing the ski to dig into the snow or ground when edged up
Solution Approach 1:
The patent optimizes the sidecut radius parameter to fall within 10-30 meters, which is specific enough to enable the double-push technique but not so strong as to create excessive pressure points. Additionally, the ski width is optimized to 40-70 mm in the central area and 30-60 mm at the ends, creating a balanced pressure distribution that prevents digging into the snow while maintaining the curved driving line for double-push technique execution.
3Shape
If conventional camber is used, then the ski exhibits strong curvature in unloaded state, but the load pressure is concentrated in two pressure points at front and rear area
Solution Approach 1:
The patent applies different geometric characteristics to different sections of the ski. The central area has a width of 40-70 mm optimized for load distribution, while the end areas have reduced width of 30-60 mm. This local differentiation creates a more homogeneous load pressure distribution across the ski surface during operation, preventing concentration of stress at specific points while maintaining the necessary camber curvature for performance.
Data Source
Figure 1~2
Figure 3~4
AI summary
Cross-country ski (1) comprising along a longitudinal direction (2) an end section (7) with a ski end (8), a middle section (5) with a binding zone (6) for attaching a binding and a starting section (3) with a ski tip (4), wherein the cross-country ski (1) has a total length (Ltotal) along the longitudinal direction (2) and the middle section (5) extends along the longitudinal direction (2) over a middle section length (LM) which is 50% of the total length (Ltotal), and wherein the cross-country ski (1) has a sidecut at least in the middle section (5).In order to enable the application of the double-push technique without the need for an intermediate jump between the first and second leg push-off, it is provided according to the invention that the cross-country ski (1) is designed such that, in a loaded state of the cross-country ski (1), a load pressure (P) acting from a running surface (9) of the cross-country ski (1) on a flat surface (17) in the middle area (5) is greater/equal to the load pressure (P) in the beginning area (3) and/or in the end area (7).