It’s Just Science

Since I started training for the Birkenbeiner I have been going for a long ski every Friday. Last Friday’s workout went well and it was an enjoyable day; the previous Friday was disastrous and I was exhausted at the end of the workout. On the day that went well, I skied 25-kilometers on a relatively flat course and it took me only 150 minutes–at that pace, I could finish the Birkenbeiner with a time of 5 ½ hours. On the day that didn’t go well, I skied 20 kilometers on a hillier course and it took me 157 minutes, which would give me a time close to 7 ¼ hours for the Birkenbeiner. On both days I had the same weather and the same snow conditions, so you may be thinking that it must have been the hills that slowed me down. That would be incorrect–I applied the wrong grip wax for the icy conditions that day.

The proper grip wax is so important if I want to do well at the Birkenbeiner. At the elite levels, it is even more important if the athlete wants to finish in the medals. At the Vancouver Winter Olympics, the Norwegian team blamed the wrong wax selection as the reason they did poorly in an event. The Norwegians usually don’t make these kinds of mistakes and normally dominate cross country ski events at the Winter Olympics. They have access to the latest scientific research from the Norwegian University of Science and Technology where the physical demands of cross-country skiing, aerodynamics, and the physics of ski glide are studied.

To understand the science of waxes you must understand the mechanics of how a cross-country ski functions. A cross country ski is cambered in the middle of the ski which is where the grip wax is applied. Glide wax is then applied to the rest of the ski. When you kick off during your stride you push the camber down to make contact with the snow and that will allow the wax to grip the snow. During the glide portion of the stride, the camber is not in contact with the snow, allowing the ski to glide between kicks.

For an icy track, a soft grip wax is needed because it can easily bind to the snow that has lost its crystalline structure when it melted. The wax creates the necessary friction for the skier to apply a backward force on the track and, according to Newton’s Third Law, an equal and opposite reaction will accelerate the skier forward. On my disastrous day, I applied the correct glide wax but I needed to use a softer grip wax. The track that day was like a freshly flooded skating rink, so my softest grip wax could not grip the ice; as a result, I used mostly my poles to get around that day – – it was exhausting.

The following week the weather conditions did not improve, so I went to Totem Outfitters and purchased Klister. Klister is a wax that is so soft that it is a liquid at room temperature, and if applied to the whole ski, your ski could stick to a wall. With the proper grip wax on that day, I could maintain my momentum going up the hills, and then with the proper glide wax, I gained lots of speed going down. Thanks to science, it was a glorious day of skiing.