The development of the classic-style roller ski sensor is a continuation of the previously developed skate-style roller ski instrumentation. The newly developed force measurement device measures the vertical and longitudinal forces produced by the skier on a ski treadmill in laboratory conditions. The measurement results can be utilized in ski research and athlete coaching.
The classic-style roller ski sensor is a strain gauge-based force measurement device, where the forces produced by the skier cause elastic deformations in the ski frame and front axle. The vertical force produced by the skier is measured near the front and rear axles from the shear force generated in the ski frame, allowing the location of the vertical force to be determined along the length of the ski. The longitudinal force is measured from the moment generated in the front axle, which can be converted to longitudinal force when the diameter of the front wheel is known. The front wheel of the classic-style roller ski has a one-way bearing that prevents the wheel from rotating backward. This enables grip in the classic-style roller ski and causes a moment in the front axle. The ski frame is custom-made from aerospace-grade aluminum, and the axles are made from high strength steel. The shapes and dimensions of both the ski frame and axles were determined based on literature and FEM simulations.
The implemented roller ski instrumentation was calibrated at the VTT MIKES force and torque laboratory: for vertical force using force standard N01, and for moment using moment standard MN03. The maximum force in the vertical calibration was 1000 N, and for the moment, 16 Nm. Measurement uncertainty was determined from the results, and a test report was prepared. The constructed force measurement device shows good sensitivity for both vertical and longitudinal forces (1.7 mV/V), and crosstalk between the force measurement channels is low (< 1 %).
To ensure that the classic-style roller ski affects the skier’s performance as little as possible, good skiability was one of the design criteria. The constructed roller ski has a similar ski height and wheelbase as the commercial classic-style roller ski used as a design model. The weight of the constructed roller ski sensor is about 20 % greater than the model ski. Based on initial feedback, the skiability of the constructed roller ski is at a comparable level to the commercial roller ski and does not interfere with the skier’s performance. The performance of the classic-style roller ski instrumentation has been verified both as a force measurement device and in terms of skiability in real test conditions at the University of Jyväskylä’s Vuokatti ski laboratory.
The development work was carried out in the ERDF funded group project “Sports data and digitalization: new know-how and added value for the Kainuu and Vuokatti’s skiing center (CEMIS-UDDA)” coordinated by the University of Jyväskylä, which ran from January 2023 to July 2025. Following its completion, research and development work in skiing disciplines continues in the already started “Advancing sport and exercise measurement and data expertise (CEMIS-SPORT)” project (August 2025 – July 2027), also led by the University of Jyväskylä. In this project, VTT MIKES is developing trigger force measurement for a biathlon rifle, where the requirement is sufficient performance as a force device and minimal impact of the sensor on the shooting performance. Additionally, the development of the cold laboratory’s ski movement device linear tribometer continues. As part of the modernization of the ski movement device (higher movement speeds, wireless measurement sled), the force measurement of the sled in both vertical and longitudinal directions is also being developed.
