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Sooth Selector inc. (owner of SoothSki) is a spin-off from research efforts conducted under the leadership of Alexis Lussier-Desbiens at Sherbrooke University in Canada. We proudly re-invest our revenues into R&D related to sport equipment understanding and development. Here's a list of published papers by Alexis and students working with him, supported by Sooth Selector inc. 

Scientific Publications

Predicting alpine skis on-snow evaluations from measured physical attributes

15th conference of the International Sports Engineering Association, ISEA 2024
Attribute selection methods have found extensive applications in various domains to gain a deeper understanding of user sensory experiences. For instance, these methods are employed to discern the physical attributes influencing coffee taste. Such analyses typically necessitate substantial testing to build large enough datasets appropriate for the use of statistical methods. This requirement elucidates the persistent challenge of correlating user feedback with the physical attributes of sporting equipment. In the context of alpine skis, numerous on-snow evaluations are imperative, incurring significant costs, time, and effort. Additionally, the physical attributes of skis, primarily provided by ski manufacturers, are often limited in scope and lack standardized formatting. The recent publication of two distinct datasets have created a new opportunity for evaluating and modeling the performance of alpine skis based on their physical attributes. These datasets include (1) the Blister Gear Guide, a well-known ski review website, which publishes ski reviews for over 200 skis each year, and (2) SoothSki, which provides the detailed measurements of over 4000 commercially available skis. Consequently, the primary objective of this research is to develop a methodology to construct simple predictive models of Blister’s rankings. These models will utilize SoothSki's measured attributes as input and Blister's rankings as output, to ultimately offer valuable insights on ski design while also helping skiers select skis.
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Comparative Study of Ski Damping Technologies by Accelerance Maps

14th conference of the International Sports Engineering Association, ISEA 2022
Skiers are faced with an ever-growing number of alpine skis to choose from. To simplify the shopping process, skis are divided into categories based on their intended usage. However, these categories are loosely defined, with numerous categorizations available. This paper presents a methodology based on decision trees to investigate how alpine skis are currently classified by the ski industry. As an example, simple, robust, and clear classification rules have been identified from the categories used by a large retailer. The rules found are only based on the measured physical attributes of the skis. Decision trees identified a few classification rules, three or fewer in all but one case, that provide high accuracy (88–97.5%) and inclusiveness (85–100%, except for the All-Mountain category). The rules found are easy to interpret by most skiers, especially when analyzing the other attributes highly correlated with each splitting rule of the decision trees. The rules found could be used by retailers to classify skis from different brands uniformly and automatically. Such rules could also be used to educate customers and simplify their shopping experience.
Keywords: Alpine ski, Classification Tree, Decision Tree Learning, Ski categorisation
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Comparative Study of Ski Damping Technologies by Accelerance Maps

13th conference of the International Sports Engineering Association, ISEA 2020
The vibratory response of alpine skis plays a significant role in the overall skier’s experience. This response is more important than ever as skiers now demand light and approachable (i.e., soft) skis. To improve the vibratory response, many companies now offer technologies to damp the ski’s motion. Even if widely used, these technologies are still widely misunderstood. This paper presents a method based on accelerance maps to evaluate the vibratory response (i.e., bending and torsional modes up to 250 Hz) and the damping at all points on the ski forebody. A variety of commercial technologies are evaluated (i.e., tuned-mass damper, particle damper, constrained-layer and rod activated viscoelastic bushing) and compared to the more traditional effects brought by adjusting mass, bending/torsional stiffnesses and construction.
Keywords: vibration; damping; alpine skis; accelerance map; modal analysis; tuned-mass damper; particle damper; constrained-layer; stiffness
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Historical Trends in Alpine Ski Design: How Skis Have Evolved Over the Past Century

13th conference of the International Sports Engineering Association, ISEA 2020
Alpine skis have changed dramatically in the last century. Long and straight wood skis have evolved into shorter lengths and now contain a plethora of modern materials. Shaped skis have become the norm. Today’s skis also offer a variety of waist widths and shapes to cater to specific uses. By studying how skis have evolved, it is possible to gain insight into how the design of alpine skis has progressed. To do so, the mechanical properties of 1016 skis, from the 1920s to 2019, were measured with a machine developed at the University of Sherbrooke. The resulting data are used to calculate various geometric, stiffness and performance parameters. The evolution of these parameters over the years is analyzed. This analysis provides a better understanding of the evolution of ski design and shows when the introduction of new materials and shaping concepts has changed the way skis are designed.
Keywords: alpine skis; camber; mechanical properties; stiffness; sidecut; rocker; shaped skis
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A Method for Measuring the Bending and Torsional Stiffness Distributions of Alpine Skis

12th conference of the International Sports Engineering Association, ISEA 2018

Directional stability is an important performance criterion for alpine skis and has been shown to correlate with the second moment of running surface pressure distribution. However, this stability index is complex to measure while skiing and is not practical for testing many skis. It therefore remains unclear what range one can expect in the variation of stability between commercially available skis. In this study, the mechanical properties of 179 skis were measured and the ski deformation was simulated during a steady-state turn to evaluate the stability index. The resulting data provide insight as to what values of stability, which ranged from 0.1 to 98 N m², are to be expected. A novel parameter, the product of the force required to flatten a ski and the square of its sidecut length, was introduced. Its high correlation with a ski’s stability suggests it can be used as an accurate predictor of stability.

Keywords: stability; alpine skis; deformation; simulation
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Alpine Skiing Recommendation Tool and Performance Prediction

12th conference of the International Sports Engineering Association, ISEA 2018

Selecting appropriate skis remains a difficult task for many customers due to the lack of information provided on the bending and torsional stiffnesses of these products. This work investigates how these mechanical properties influence the on-snow ski performance and how an individual skier profile is related to its preferred mechanical properties. To do so, twelve skis were manufactured to exhibit large variations in stiffnesses. Twenty-three skiers provided on-snow feedback and skier profiles through a questionnaire. Simple and multivariable linear correlation analyses were carried out between the skier profile data, their evaluations of the skis and the stiffnesses of the skis. Strong relationships were found between the properties of the skis and some performance criteria, and between the profile of the skiers and the properties of their favourite skis. With further testing, these relationships could be used to design personalized recommendation tools or to guide the design of custom skis.

Keywords: ski; performance; recommendation; stiffness; subjective evaluation
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A Method for Measuring the Bending and Torsional Stiffness Distributions of Alpine Skis

11th conference of the International Sports Engineering Association, ISEA 2016

A novel non-destructive method for quickly, accurately and simultaneously measuring the bending and torsional stiffness distributions of an alpine ski is presented. This method, named SMAD (Stiffness Measurement through Angular Deformations), is based on measuring the angular deformations resulting from a known combined bending and torsion load. The method’s accuracy and repeatability is investigated and are on average under 2% and 3%, respectively. The coupling in the measurement of the bending and torsional deformations during combined loading due to ski misalignment in the test machine is investigated. The measured torsional deformation was found to be independent of the bending load. The measured bending deformation was found to be dependent on the torsional load but this effect could be limited by careful alignment of the ski in the test machine.

Keywords: Stiffness; Rigidity, Bending, Flexural, Torsional, Measurement
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