Alpine Ski Sidecut Geometry for Stable Turns and Terrain Adaptation

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Solution Overview

Problem

Existing alpine skis with constant or varying radius of curvature along the sidecut do not optimally balance performance and ease of handling, particularly in competitive skiing, and are not compatible with advanced skiing techniques.

Innovation Solution

An alpine ski design with a variable radius of curvature between the front and rear contact lines, featuring a maximum curvature at the waist and progressively decreasing curvatures towards the tip and tail, with the minimum width zone located forward of the boot centerline, enhancing the ski's performance and maneuverability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sidecut has a constant radius of curvature along the waist, then the ski provides stable and predictable turning behavior, but it lacks adaptability for advanced competitive skiing techniques and uneven terrain

Engineering Contradiction:
Improveturning stabilityVSAvoidterrain adaptability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The ski sidecut employs different radius of curvature values in different longitudinal zones: a first radius in the front waist zone, a second (larger) radius in the rear waist zone, and a third radius in the tip section. This local differentiation allows each zone to contribute differently to turning behavior, providing both stability from the constant-radius waist and adaptability from the variable-radius tip section for competitive skiing

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the sidecut radius varies progressively along the waist, then the ski becomes easier to control, but it compromises performance in competitive skiing

Engineering Contradiction:
Improveski controlVSAvoidcompetitive performance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention applies different radius characteristics to different zones: the front and rear waist zones maintain constant radii for predictable control, while the tip section introduces variable radius for performance. This localized application of constant versus variable geometry resolves the contradiction by providing ease of control where needed while maintaining competitive performance capabilities

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The sidecut is segmented into multiple zones with distinct radius characteristics rather than applying a single progressive variation throughout. This segmentation allows independent optimization of control characteristics in the waist versus performance characteristics in the tip section

Inventive Principle:
Principle #1Segmentation

3Stability of the object's composition

If the widest point of the ski is located beyond the front contact line, then the ski provides better glide and stability, but it reduces maneuverability for advanced turning techniques

Engineering Contradiction:
Improveglide stabilityVSAvoidturn initiation
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The invention positions the first line of greatest width beyond the front contact line for stable gliding, while simultaneously creating a minimum width zone in the tip section with specific radius characteristics that enhance turn initiation. This local differentiation resolves the contradiction between stability and maneuverability

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4309751B1Alpine ski with improved sideline
Publication Date: 2025.11.26 SKIS ROSSIGNOL SA VOIRON FR
  • EP4309751B1 patent drawingFigure 1~3
  • EP4309751B1 patent drawingFigure 4

AI summary

Alpine ski (1) comprising a tip area (2) located at the front of the ski, a waist area (4), and a tail area (3) located at the rear of the ski, a median longitudinal plane extending from the front end to the rear end of the ski, an underside formed by a glide base (7) bordered by edges, a boot mounting area (20) whose midpoint, in the longitudinal direction, is located at the level of a boot midline (BM), and having a sidecut having: - a front contact line (BP) defined as the contact line between the glide base (7) and a horizontal surface (12) on which the base is pressed when the waist (4) is loaded, which is located furthest forward, - a rear contact line (RB) defined as the contact line between the glide base (7) and said horizontal surface, which is located furthest backward, - a front line of greatest width (BW) located further forward than the front contact line (BP),- a line of greatest rear width (PII), located further back than the rear contact line (PB), - a minimum width zone (PIII) located in the skate zone, said sidecut having a variable radius of curvature between the front contact line (PA) and the rear contact line (PB), characterized in that the width of the ski, measured perpendicular to the median longitudinal plane, at the level of the front contact line (PA) is strictly less than the width of the ski measured at the level of the rear contact line (PB) and in that the minimum width zone (PIII) is located further forward than the boot midline (MC).