Today’s post is only superficially about the physics of waxing cross-country skis. In reality, I want to share with you how an inquisitive mentality spreads throughout all facets of life. Even if you’ve never been skiing, walked on snow, or cared about physics, I hope the inquisitive side of you will keep reading.
Getting traction on something slippery
Cross-country skiing is about moving smoothly over snowy terrain. To do so requires two interleaved types of movement: gliding smoothly, then pushing along to regain momentum for the next glide. Traditional skis are bowed in the middle, giving rise to two parts of the ski. The front and tail are slippery to give glide. The middle is grippy to give kick. With skis matched to the person, standing on both skis leaves the grippy middle bit out of the snow, whereas standing on one ski engages wax with the snow. Once I started to visualize the kicking down motion to get grip with the snow,1 I really started to grow in my skills.
That’s not all our physics, yet. Even more rules are useful for understanding how wax works. For the wax to grip the snow when we engage the central part of the ski, the wax has to have the right amount of stickiness with the snow. Imagine touching honey, with the honey at three different temperatures. If honey is cold, it’s like hard candy and you can touch it without sticking. If it is about room temperature, the honey sticks to everything and makes long strings of mess. Just slightly cooler than room temperature, honey is sticky without being gloopy. It’s not a great temperature for using in the kitchen, but you get the idea. The honey is the ski wax, and your finger is the snow. We want just enough stickiness between them – not so much it’s gloopy and not so little it’s brittle.
The temperature chooses you in skiing. So we choose wax depending on the temperature.2 Red wax is designed for warmer weather, for example, and it turns as hard as rock candy in freezing temperatures. Blue wax is for cold, and purple is for somewhere in between. I learned to ski as an adult while living in Norway. My house is at 750 m above sea level. I can walk out my door and up to the ski tracks at 1000 m elevation and it can be 10 °C warmer (yes, it is often warmer higher up when the weather is bright). The tracks themselves wander between 800 m and 1200 m, with streams, bogs, sunshine, and shadow creating large temperature variations in the snow. Which color wax to use?
Skis that aren’t getting traction is mentally painful for me. I can get so angry I shout into the nothing (lucky for me I ski where I’m often all alone), frustrate myself to confusion, and allow myself to ruin an otherwise amazing adventure. My moment of inspiration was when I threw out “perceived wisdom” and realized that I could wax my right and left ski different from each other. I mean, I already had a symmetrically crappy experience. Would I be happier with at least one ski getting bite into the snow?
I didn’t understand on that day, but I recognize now that I was living in somebody else’s vision of skiing. Skiing in the Oslo area, where I first learned, feels like being in a parade or being on show. Am I wearing the right clothes? Do I have the right skis? Am I doing this right? After having empty forest trails all summer and autumn, I suddenly was subject to inspection. To top it off, Norwegians won’t look a stranger in the eye in town or sit with a somewhat-acquaintance on the bus. But, put them on skis in the middle of nowhere and every passing gets direct eye contact that suddenly feels like an analytical stare. Being prone to imagining external criticism, I was about ready to give up.
I mixed some purple wax on top of my blue, but only on my right ski. I wanted to know if it helped. But, more than that, I wanted to feel if it helped. It was great. I could kick along with my right foot and push harder with my poles when kicking with my left foot. With the patience gained from years in the laboratory, I kept going without trying to “fix” the unmodified left ski. Maybe when I got higher up the snow got cold again, and my left foot now had the stickier grip. I don’t honestly remember. What I remember is that I had invented an experiment for myself.
Even on days with predictable conditions, I wax my left and right skis differently.3 Just this weekend, I was heading on a random adventure at the eastern edge of Rondane National Park. I threw on a longer streak of wax on my left ski than is called for on manicured trails. This way, I get grip great grip on unpacked snow, great grip on groomed trails, and a pile of learning experience. Lucky me, I found a snowed-over road leading deep into the park. My skis, my heart, and my legs were ready to turn away from the groomed trails and cut my own.
Be driven, but know why
Now, in my fifth year of living in Norway, I know that I go out skiing to move my body, enjoy being warm in a cold winter, see the world anew when covered in snow, be quiet in my thoughts, get home safely, and learn something new. I have decided that as I learn to ski, to wax my skis, and to be adventurous in the mountains of Norway, I’m going to keep waxing my left and right skis different from each other. Why?, because it helps me have a fulfilling day of exploration.
It’s rare that I get any response other than a derisive laugh when I tell a Norwegian what I do with my skis. Most grew up on skis and move as naturally as I feel when I lace up my hockey skates. I don’t recommend others to try what I do, just like I wouldn’t tell Usain Bolt to wear two different shoes so he could learn how to run. There’s so much playfulness and experimentation we give up on when we’re adults. Or when we think we’re experts.
I’m going to keep experimenting, to see what I can learn. If there’s a day when I wax both skis the same, it’s because that’s the experiment I am ready for and the lesson I want to absorb. Not because someone else has told me it’s what I should do.
Note added in proof
Apparently Marie recently wrote about a similar topic on Outspoken Images. No, we don’t plan our writing strategies together, but we do live in the same house.
1) I learned first that skiing was about shifting your weight from foot to foot, but I found this rather trivial and unpropelling advice. We all shift our weight side to side when walking. As a person who spends lots of time running on uneven terrain, I know many ways to shift my weight. Telling me what the result is often backfires; helping me understand the principles for how to effect a specific result is my key success. We all learn differently.
2) There are more subtleties here, but that’s a post for another writer
3) Classic skis are the same left and right – there is no handedness to them. I mark mine now, to differentiate.