Ski technology: Pressure points determine properties
Pressure points are crucial for how a ski will behave. A cold snow ski behaves differently than a ski built for wet and warm conditions, simply because they have different constructions.
Ever wondered why a cold conditions ski doesn’t run very well with klister, even if the kick zone is tall enough to accommodate klister? It might feel as if there is significant suction, despite rilling and waxing perfectly for the conditions. Likewise, a soft klister ski will feel slow in cold conditions, even though it should be soft enough to provide sufficient grip with hard wax. It just doesn’t really want to glide. And it’s not your fault.
Let’s take a look at physics and construction. Warm and wet conditions skis are not built for cold snow, and vice versa. Much of the ski’s construction is based on pressure points, and these pressure points contribute to determine the ski’s performance in different conditions.
Cold conditions skis create water
In a cold conditions ski, the pressure points, which are located in front of the kick zone and behind the kick zone on classic skis, are long and not very hard. That’s because long, relatively soft pressure points create a longer glide surface to the snow.
The friction in this glide zone creates heat, which in turn creates a thin water film on the snow that the ski glides on, Stian Groenaas explains. Groenaas, who works in the Madshus service team, worked almost a decade with the Norwegian national teams as a wax tech.
“When you create more water in cold conditions, the ski glides better,” Groenaas says.
Warm conditions skis drain water
Skis designed for warm conditions reverse the physics of the cold conditions ski. Warm conditions skis have short, hard pressure points. When the tracks are wet, the skis need to drain water in order to reduce the suction, and less surface on the snow equals less suction. Consider two panes of glass with water between: they’re hard to separate due to suction. You don’t want that with the ski and the track, Groenaas explains.
“In wet conditions, you want to drain the water away. That’s why warm conditions skis have short, hard pressure points. There is too much water, and the water reduces the glide,” Groenaas says.
Pressure points in a zero-conditions ski is right in the middle between the long, soft ones of cold conditions skis, and the short, hard ones of warm conditions skis.