The Performance Side of CADS
Tony Nespor, Head Engineer, CADS USA, Inc.
Stability & Control
Skis gliding over an extremely smooth and soft snow surface, even at high speed, are very stable. However, this stability will quickly diminish as the surface conditions change. The legs, acting as springs and shock absorbers, must constantly compensate for this changing surface condition to keep the upper body stable. Upper body stability and excellent balance are basic fundamentals for a good skier. Brain, eyes and muscles must work in perfect harmony.
As a skier glides down the hill picking up speed, cautiously scanning the snow surface, he will eventually reach a point where he must slow down. This point varies with every skier, depending on his or her ability. It depends on how well the brain, eyes and muscles can compensate for the constantly changing surface conditions. The faster the skier travels, the quicker he or she must respond.
Have you ever seen the TV commercial of a car speeding over a series of small bumps to demonstrate the riding comfort? Did you notice how quickly the wheels move up and down, while the body remains virtually still? Let’s take a closer look. As the wheel rides over the bump, the upward movement of the wheel compresses a large spring. As the wheel travels down the bump, the energy stored in the spring is released. This energy presses the tire against the other side of the bump, maintaining solid contact over the entire surface. Since contact of the tires with the road surface has not been interrupted, excellent stability and control are maintained.
Our legs work in a similar way, but with three exceptions: (1) our muscles cannot store energy as springs can; (2) they are much slower in response; and (3) they get tired quickly under a heavy load. Skiing a rough course in a straight line can cause a skier to reach a speed (while it may be surprisingly slow) at which he begins losing snow contact. When a skier loses control and stability, he must slow down to prevent a fall. Under similar conditions, but not as steep, the skier’s speed will eventually stabilize. His muscles will quickly tire and he begins to lose control. To prevent a fall, he must stop and rest.
When a skier approaches a bump at slow speed, he may be able to anticipate it by first extending his legs, then bending his knees as he goes over the bump, and finally extending his legs again to maintain snow contact on the far side. However, even at moderate speeds, the reaction time and muscle speed of the human body is too slow to perform this maneuver effectively. Snow contact will be lost, causing instability.
CADS preloads each ski with a pressure derived from stretched, specially engineered rubber bands, which have a much faster response time than human muscles. When approaching a mogul with CADS, the skier’s leg muscles are more relaxed, and thus faster, more flexible and responsive, since some force comes from the stretched rubber bands.
When the skis encounter the bump, the legs bend more easily. The upward force on the skis stretches the rubber band, which stores the energy just like the car springs. Upon passing the crest of the bump, the increased force in the rubber bands instantly forces the skis down on the far side of the mogul, maintaining snow contact. Stability and control are dramatically enhanced.
In racing, speed is a function of wind resistance, friction of the skis on the snow, skiing line, and snow contact. Let’s examine the CADS contribution for each of these.
Our quadricep strength is directly proportional to the angle at which the knee is bent. We are strongest when we stand up and weakest when we squat. To demonstrate this, try a simple test. Stand on one leg. Bend this leg several times so your body moves up and down a few inches. No problem there. Now fully squat close to a wall. Put your hand on the wall for balance and lift one leg off the floor. After balancing yourself, try to get up on one leg. Can’t do it? Don’t be surprised. Not too many people can. The more we bend our knees the weaker our legs are. The CADS lifting force works the opposite way. The greater the flexure of the knee, the greater elongation of the elastic band and therefore the greater the lift.
Aerodynamic stance is very important. A full tuck position while traveling over rough terrain at high speed will quickly reduce a skier’s strength reserves. CADS enables a downhiller to spend more of the course in a tuck. Because his upper body is supported by stretched rubber bands, his physical strain is sharply reduced. He does not have to preserve his strength. He can therefore concentrate more on refining and maintaining the shape of minimum wind resistance memorized from wind tunnel exercises.
How could CADS affect friction between the skis and the snow? Isn’t this a matter of base finish and wax? Not if the snow surface were absolutely smooth. When skis travel on the rough snow surface, the friction between the ski and the surface rapidly changes. As we learned previously, at greater speeds, the human body cannot maintain constant snow contact. Failure to perfectly absorb and extend when speeding over a small bump causes excessive pressure between the ramp of the bump and the ski. Increased friction robs speed. The same excessive pressure is responsible for lost snow contact, and the skier is momentarily airborne. When the skis make contact again a split second later, the force with which the skis hit the snow is substantial. Increased friction and snow displacement at the point of impact steal energy and therefore speed. The quads of a CADS skier are supplemented with rubber bands. His legs are stronger, more flexible and respond quicker, so he can compensate better for the changing surface conditions. When traveling over the same bump at the same speed, the ramp pressure on the skis will not reach the same peak level. Let’s take a closer look.
When the skis reach the ramp of the mogul, there is a change in the direction in which the skis travel. Kinetic energy is built up in the skier’s body as he moves down the course. This energy is stored in proportion to mass, which is concentrated in the skier’s torso. Every change in direction made by the skier causes his energy to be reduced. It is important to remember that the less his body deviates from a straight trajectory, the faster he will travel.
Pressure between the ski and the ramp of the mogul will be more consistent in the CADS skier, because of the smooth, instantaneous and tireless help from the rubber bands. To demonstrate this, picture yourself dropping an egg from the window of a two story building onto a piece of 12" thick, soft foam rubber. It will not break no matter how many times it is dropped. Now try to catch the egg with your hands, the same 12" above the ground. There are two potential pressure peaks which will break the egg. The first is when the egg initially contacts the hand. If not properly timed, a second pressure peak will occur when your hand hits the ground. In many tries, you could get lucky but because we are not capable of eliminating pressure peaks, the egg will almost always break. When skiing with CADS, pressure peaks—and therefore friction peaks—between the surface and the skis are reduced.
Now let’s think about line. The racer who skis the shortest distance while still clearing the gates has an advantage. This depends on strength and edge–hold. Simply put, because CADS is a muscle augmentation technology, it gives muscles more power to fight centrifugal forces. Legs do not become exhausted. Turns are tighter and look the same throughout the entire course of the run.
Edging is important, and as a course gets rutted out, edging becomes more challenging. The downward spring force of CADS takes the chatter out of the ski and the tails do not skid. In the turn, with the ski on edge, the force line is exactly in the center of the ski. To demonstrate this, take a hard cover book and lift and hold one end about 3" off the table. Let’s pretend it’s a ski on edge. Place the other hand exactly in the middle of the book and apply pressure. This pressure will try to flatten the book against the table, and to prevent this, we must resist. The same applies when edging. The force on the ski is trying to flatten it and we must work harder to resist. Powerful dynamic turns require great edge holding skills; otherwise edge is lost.
Now move your hand right over the supporting edge and apply the same amount of pressure. As you can see, no resistance is necessary. CADS has a specially engineered swivel, which shifts the downward spring force toward and past the supporting edge, depending on the degree of angulation. This offsets the flattening force and the skier maintains a stronger edge.
Ability to maintain good snow contact under constantly changing surface conditions requires fast reflexes, excellent coordination, strength and depth of experience. Density of the snow is a major factor. Soft and fluffy snow is more forgiving; tightly packed, hard and icy snow requires a more refined technique. We have already learned the benefits of CADS on snow contact in the section on stability and control. The effect becomes visible when following a speeding CADS skier, even on relatively smooth and hard snow. It’s very impressive to see CADS at work. The extremely rapid up and down motions of the upper termination points of the rubber bands indicate instant surface tracing capability. We can see continuous storage and release of energy, ranging from a few ounces to tens of pounds per ski, which would otherwise be wasted.
Skiing is a beautiful but very physical sport. Think of skiing as divided between inspired work and busy work. The busy work is load-bearing. The inspired work is responding, controlling and steering. Perhaps it is obvious that CADS does the load-bearing. Ski resorts are spending millions of dollars on grooming to make this sport easier and safer to a broad spectrum of skiers. Despite these efforts, fatigue, loss of control, and instability, leading to fear of falling and injury, play a big role in this sport’s expansion. CADS gives skiers more strength, control, stability and confidence. They learn faster, with less chance of injury. It is a new, relaxed, easy, dynamic style of skiing. CADS is for every age group and level of skier, with the exception of a pure beginner. Our bodies were not designed for skiing. Despite all the innovations in this sport, many of us pay a terrible price: injured and damaged knees are the common result of years of skiing. As ski equipment evolved over the decades, CADS has been the biggest breakthrough in sports equipment history. It looks strange, but don’t worry, we’ll all get used to it. Many years from now, standing somewhere on the top of a mountain, we will quietly thank those who made this possible. Instead of having been forced to quit years ago, we can still enjoy the sport we love so much, the sport of skiing.