Edge control is the ability to tip the ski onto its edge and adjust the angle between the base of the ski and the snow. This angle has a significant impact on both speed and direction of travel. Relative to a ski that’s flat on the snow. a low edge angle results from tipping the ski slightly on edge. A high edge angle results when the ski is tipped more on edge, increasing the angle between the base of the ski and the snow. Effective edge control involves using only the amount of edge angle necessary to accurately affect the path of the ski through a turn, promoting a gliding action of the skis. Skiers must move laterally to balance against the forces that act on the skis when they are tipped on edge. Inclination and angulation are terms that are commonly used to describe body movements relative to the edge-control skill.
Inclination
Inclination occurs when the skier deviates from a vertical position. In skiing, inclination is the general term for any lateral movement of a skier toward the inside of a turn. Some degree of inclination is always present in order to balance against the forces in a turn. The amount a skier inclines depends on the magnitude of force, which is influenced by edge angle, turn radius, pitch of the hill, snow conditions, and speed of descent.
Angulation
Angulation refers to movements that create angles between body parts. Two types of angulation are commonly used in skiing: hip angulation and knee angulation.
Hip Angulation
Hip angulation refers to the angle create at the hip joint. A small amount of hip angulation can occur by tilting the pelvis. The greatest degrees of hip angulation come from a combination of leg rotation, abduction, and adduction of the femurs, and torso flexion, primarily at the hip joint. Leg rotation at the hip joint creates a separation between the upper and lower body. This allows the upper body to remain more upright, or bend toward the outside ski, as the lower body tips to the inside of the turn. The combination of movements creates strong, stable alignment. It allows a skier to adjust edge angle while maintaining balance toward the outside ski as forces increase in a turn. This type of angulation is most apparent through the shaping and finish phases of turns.
Knee Angulation
Knee angulation refers to the angles created at the knee joint. The knee joint has little lateral movement, especially when the leg is straight. In this respect, knee angulation is mostly a result of lateral and rotational motion of the leg combined with bending the knee joint. Knee angulation, while present in most turns, is most apparent in shorter turns where the forces are not long-lasting, or in instances when greater edge angles are required at slower speeds. As forces increase due to greater speed, hip angulation keeps the body in stronger alignment, although slight adjustments in knee angulation can be sued to fine-tune edge angle. Note: Banking describes the movement of a relatively straight body leaning toward the inside of a turn. Typically, with insufficient pressure on the outside ski, the edge cannot grip the snow effectively, and the ski slips or slides. The movements a skier chooses to use to edge the skis depend upon experience level, desired turn shape, pitch of the hill, terrain, snow conditions, speed of descent, and desired action of the skis.
Edge Control Outcomes: Action of the skis
Skis are designed to turn while they are on edge. The edge-control movements described previously are critical to tip the skis, and it’s the angle of the skis on the snow that ultimately determines how much force acts on the ski. Some turns require higher edge angles, while other turns benefit from lower angles. Just as certain terms describe ski actions relative to the rotational component, the following terms describe ski performance relative to the degree of edge engagement.
Sliding
Sliding is the forward travel of a flat ski as demonstrated in a straight run down a slope. A sliding ski leaves a straight path in the snow as wide as the ski’s width. Subtle edge angle adjustments may be necessary to keep the skis flat on the snow.
- Flat skis travel straight ahead
Slipping
Slipping, which is also known as “sideslipping,” refers to the action of the skis as they travel in a direction sideways to the length of the ski. The slipping action can occur straight down the hill or in a forward or backward sideslip in which the skis slip sideways while traveling diagonally down a hill. The edge angle adjusts the speed of descent without creating a turning force. Higher edge angles slow the descent, while lower edge angles allow speed to increase. The degree the skier banks or angulates is a function of balance relative to the angle of the skis. Slipping will leave a path in the snow that is as wide as the length of the skis.
- Edge angles may range from nearly flat to significant
- The function of the edge angle is to slow or increase the speed of descent without creating a turning force
- Inclination is required to balance on an edge ski
Skidding
Skidding blends forward and sideways action of the skis. The skidding action covers wide range of ski performances, and represents the most common interaction between the skis and snow. One end of the skidding spectrum is very similar to slipping with sideways travel, except the skis move through some degree of an arc instead of a straight line. The other end of the spectrum is very similar to carving, with the skis moving forward along their length, and having only a slight amount of sideways travel. Edge angles for skidding cover the entire range from nearly flat to steep, depending on the skier’s desired outcomes and experience level. Skidding may leave either a wide path in the snow or a very narrow path, depending on the degree of sideways travel through the turn.
- Edge angles may range from nearly flat to very steep
- Edge angle contributes to the shape of the turn, affecting the skier’s speed of descent
Carving
Carving refers to the action of an edged ski traveling forward along the length of the ski with very minimal to no sideways travel. A high edge angle allows the bend of the ski to create the arc of the turn, as the tail follows in the path cut by the tip. As the turn develops, the skier increases inclination (angulation) to maintain balance with forces that build, and to keep the ski carving through the snow. A carving ski leaves a very narrow track in the snow. Any minimal amount of skidding is not visible in the action of the ski, or the track left in the snow. The term “arcing” is also used to describe the action of the tail following precisely in the path cut by the tip.
- The function of the edge angle is to access the turning force (centripetal) and minimize the braking force (friction).
- The arc of the turn is created by the design of the ski
- Higher edge angles and greater degrees of inclination (angulation) will be present with greater speeds and force
Edge Control and Balance
Any lateral movement a skier uses to increase or decrease the angle of the skis on snow affects balance. If a skier moves too far to the inside of a turn and the corresponding edge angles are too high, the skis will tend to go straight and not continue in a curved path, and/or the skier will fall onto his or her tip. If a skier does not move far enough to the inside of a turn and the corresponding edge angles are too low. the skis won’t hold their intended path; they will slip or skid sideways, compromising balance.