Ski Shape and Profile
Ski Profile: Camber vs Rocker
There are many variables that come into play when talking about how a pair of skis will perform. Ski shape is a big one. The camber or rocker of a ski determines the effective edge which plays a huge role in determining performance.
Benefits of Camber
For many years, all skis existed with varying degrees of camber. Camber refers to the bowing of a ski; having the center of the ski higher than the tip and tail when un-weighted. Camber is very effective for giving the best edge hold and "pop". This is due to the fact that when a skier's weight is compressing the camber, it directs equal pressure to the full edge length. The "pop" comes from the camber rebounding to its unweighted shape when weight is removed (think turn transitions).
In general, the best resort-based carving skis have a fair amount of positive camber to allow for quick and snappy turn transitions, as well as evenly distributed pressures along the full edge length.
The Emergence of Reverse Camber and Rocker
Within the past ten years, a new way to profile a ski has gained popularity. The addition of negative camber was first used in very wide powder skis. The idea was to utilize a snow ski the same way a water ski is used; maximum surface area for flotation and a tip and tail that are higher than the center of the ski to optimize a ski's ability to plane over the surface of the water. The same characteristics were adopted in making powder skis - large surface area and a reverse camber.
As this new profile gained popularity through the mid-late 2000s, ski manufacturers wanted to incorporate the best performance gain of both technologies. They wanted to combine the tenacious edge grip and "pop" of camber with the flotation and ability to plane in soft snow of reverse camber. Thus, the advent of the rocker ski.
As more people started to ski the camber/rocker hybrid skis, the industry noticed how much of an improvement they were over traditionally cambered skis for almost all types of skiing. This improvement came from having a shorter edge length (discussed below). The edge engages the snow closer to the foot and allows the skier to have an easier time conducting pressure to the point of engagement. By having the foot closer to the point of engagement (and disengagement with tail rocker), the skis can enter and exit from their turn radius with greater ease. The risk of “catching an edge” is greatly reduced.
Effective Edge
The effective edge on a ski is the engagement length of the edge on hard snow. With traditionally cambered skis the effective edge length is just a few centimeters shy of the physical length of the ski. Once rocker skis became popular, it became harder to judge skis by their physical length since, depending on the amount of rocker, the effective edge length can be just about any length.
The best way to determine a skis's effective edge length is to place the skis base-to-base, or on a flat surface, and depress the camber. Note the contact points of the tip and tail where the edges begin to turn up. That length, in between the up-turns of the tip and tail, is the effective edge.
Any ski with a very short effective edge (either reverse camber or lots of tip and tail rocker) will be unstable and slippery at higher speeds. In choppy, variable conditions or ice, a ski with a short effective edge will not hold an edge as well as a ski with a longer effective edge. A rockered or reverse-camber ski will excel in soft snow and powder. The ski will maneuver well and pivot easily in tight trees and technical lines. Additionally, a ski with a short effective edge and heavy rocker will float above the snow and is easy to control.
A longer effective edge (fully cambered skis, or with just a little tip rocker) will be very stable at higher speeds. The control and bite of the edge on hard and variable snow will be precise and solid. But as the snow gets softer, and the terrain gets tighter, the ski will be harder to move. There will be increased propensity to ski below the snow surface in powder, and quick maneuvers will be more difficult.
Short vs Long Effective Edge: Pros and Cons
Short Effective Edge- Not great control at high speeds
- Less stability in difficult/variable snow conditions
- Pivot with ease in tight terrain
- Will plane above soft snow
- Stable at high speeds
- Great control on hard/variable snow
- Harder to manuever in soft snow and tight terrain
- Sinks below soft snow surface