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Three connected cold rooms in the yard of the Vuokatti Sports Technology Unit measure sliding friction between cross-country skis and snow with a linear tribometer. The temperature of the tribometer track can be adjusted from -1°C to -20°C while the environment set within the interval of +15°C to -20°C. Testing the friction of different skis helps matching skis with similar sliding characteristics for the Finnish cross-country national team.

On an October Tuesday, the Finnish national team ski service is still not seen in the laboratory, but professor Karlis-Agris Gross of Riga University of Technology has traveled to Vuokatti after reading a publication about the tribometer for ski measurements: (Lemmettylä, Teemu, et al. Frontiers in Mechanical Engineering 7 (2021): 661947). Gross is interested in how the conditions of the low temperature laboratory can be utilized for measuring friction of a skeleton slider. The interest in ice friction is not new since Latvian luge teams have previously utilized the linear tribometer in the sports technology unit. The linear tribometer is well suited for measuring the friction of skeleton sliders.

"Friction has also been measured with the tribometer for mini luge sliders. At the start, we were surprised that the tribometer could also be used for measuring ice friction for luge sliders" says Teemu Lemmettylä, ski service specialist and project manager of Vuokatti sports technology unit.

Vuokatti's unique testing conditions may be more familiar in the world than within Finland. Active communication within the international scientific community brought Gross to Kainuu to see if friction measurements could be measured on full length sliders used by athletes.

"Every year we look for better facilities to measure ice friction. I noticed your publication and now I'm here. International communication is extremely important," Gross highlights.

In Finland, interest in measuring friction has not spread very widely.

Teemu Lemmettylä is excited about international cooperation and the opportunity to learn more about ice friction.

"This also supports the measurement of snow friction. Snow and skis are a much more complex combination, but ice friction measurements require greater accuracy, gives a reason to develop the tribometer.”

Benefit for both – skiing and sledding

So how could skiing and sledding complement each other in friction measurements? According to Gross, it can and both sports can benefit from studying both snow friction and ice friction.

"I think this is an excellent opportunity to combine research. The surface of the ice is monolithic and uniform. The surface of the snow is much more complex. It gets compacted and the conditions on the snow surface change all the time. It would be easiest to start by measuring ice friction and then apply the results to measuring snow friction. At the moment, here in the laboratory, it is done the other way around, starting with the more complicated, i.e. measuring snow friction, because skiing is more popular and competitive in Finland.”

Are there similar measurement opportunities in Latvia?

"In Sigulda, there is a bobsled push-start facility for training, but there is no control of the air temperature and humidity. In Vuokatti, there is control   of air temperature, humidity, and ice temperature. Control of all three factors is vital for a reliable and reproducible measure of friction.” says Gross

"EU funding through the project "M-LUGE" (Nr.ESRTD/2022/15) made this new collaboration possible”, adds Gross.

"The autumn pilot measurements gave promising results, for a larger study in spring. The visit also led to a new test method for rapidly testing friction of different ice compositions. An abstract has been submitted to Tribology 2025 to share the new development to the international community. The goal is to write several scientific publications in collaboration, that uses the Vuokatti's low temperature laboratory", Lemmettylä opens up the future.

Also Professor Vesa Linnamo, head of the sports technology unit, is very happy with the upcoming cooperation

“This is an excellent example that expertise of the Ģ��ֱ�� in Vuokatti is recognized internationally, leading to international collaboration partners."

Vuokatti's low temperature laboratory and linear tribometer will be improved during the winter. The goal is to increase the accuracy of the tribometer, and test over larger distances, for testing at faster speeds.

Vuokatti Sports Technology Unit (JYU-Vuokatti) is part of the Faculty of Sport and Health Sciences of the Ģ��ֱ��. JYU-Vuokatti specializes in interdisciplinary and applied research in biology of physical activity as well as master's and doctoral education in sport science. The unit has been operating for over twenty years in Vuokatti.