Mono Ski Terminology (A-O)

Aluminum. This is a material often used in the fabrication of mono-skis and lightweight wheelchairs (usually 6061-T6). Commonly used in the aircraft industry, aluminum can be painted or anodized but will corrode if left untreated. It is easily machined and tends to get stronger when cold-formed.

Angulation. This is the act of shifting body mass to the side in order to put the ski on edge. To balance this action, an equal portion of body mass must lean in the opposite direction or the ski can lose its edge and slide out from under the skier.

Body Height. Mono-skiers can't effectively shift their center of mass if they're seated too high. The center of mass should be as close to the snow as possible without touching the snow when leaning into the hill on a steep slope.

Bucket Seat. This is the basic seat type that often comes on a mono-ski; it is usually a plastic or fiberglass shell. A simple pad may be provided, but users generally customize their seating and padding. A Jay protector is often used in program equipment for pressure relief. The seat should allow good pelvic positioning and the ability to lock the pelvis to prevent twisting. Individual knee straps are also important for locking the pelvis in position.

Cage Seat. This is the type used on road-racing wheelchairs. The concept hasn't been tried on a mono-ski, but it has potential for adapting to different body sizes.

Canting. Cants are plastic wedges placed between the ski and the ski boot. Mono-skiers with scoliosis (curvature of the spine) or differences in left-/right-side muscle strength may need canting. Users can cant the seat relative to the frame, but it's better to cant  between the frame and the ski.

Center of Mass. This is the point at which the mass of the body and mono-ski are concentrated. Positioning the center of mass over the proper spot on the ski is essential to making turns. Mono-skiers have much less ability to shift their center of mass forward and backward than stand-up skiers. To maintain balance when making turns, the center of mass must also be centered properly on the ski to the left and right (see "Fore and Aft Adjustment").

Chairlift Clearance Height. Chairlift height is affected by the amount of snow on the load ramp. Since April 2000, the new aerial tramway standards require that ski areas disclose the seat loading height at the load point for all chairlifts. This is the distance from the load point to the top front edge of the chairlift seat. If you place your mono- or bi-ski in the chairlift loading configuration you can measure this height with a tape measure while you're sitting in your equipment on a firm surface. This chairlift seat-height information is a great safety feature for adaptive skiers because it tells them whether they can load when the lift is running at full or slow speed, or if it needs to be stopped to give them more time or get assistance.

Composites. This is a combination of woven materials (e.g., fiberglass, Kevlarª, graphite) infused with liquid resins (e.g., polyester, vinylester, epoxy) that harden. Epoxy resins are less water-permeable and provide great flexibility and durability at all temperatures.

Compression. Stand-up skiers use their knees to compress their bodies as they go over bumps. If they didn't, they'd get a jolt and possibly go airborne. Mono-skiers have to let their shock absorbers do the work. Some have adjustable slow/fast compression rates. For example, rolling over a bump would cause a slow compression rate, while hitting an abrupt one would cause a fast rate.

Dampener. If you remove the spring from a shock absorber, you have a dampener that controls the rate of compression and rebound. A dampener is a piston with hydraulic fluid on both sides. A tiny hole in the piston limits the rate at which it can move through the fluid. A change in the hole and valve size affects the slow/fast rate of compression and rebound. Some dampeners can't be adjusted.

Evacuation Harness. Evacuation equipment provided for stand-up skiers in the event of a chairlift malfunction would most likely be useless to adaptive skiers, so they should carry a personal evacuation device at all times. Adaptive sports-equipment standards were in the pre-balloting process in Fall 2000, and a complete adaptive-equipment standard for evacuation-harnesses testing should be completed in 2001.

Flex. This ski characteristic may be linear or nonlinear, soft or hard. The mounting of the mono-ski to the ski should not interfere with the natural flex. The heel piece on a standard binding is spring-loaded to allow the ski to flex naturally. On the mono-ski, if the distance between mounting bolts cannot change as the ski flexes, the bolts will eventually tear loose. This can cause the ski to break near the mounting plates.

Foot-support Height. When full mono-ski suspension compression occurs, your feet should be as low as possible without hitting the snow. When your feet hit during the driving portion of a turn, you completely lose your edge; therefore, always consider the slope's steepness.

Fore and Aft Adjustment. This is a mono-ski's most important adjustment feature. Able-bodied skiers can shift their center of mass fore and aft over the ski in a much broader range than mono-skiers. As a T10 paraplegic, I have a total range of 12.5 cm (about 5 inches), while a stand-up skier can normally shift 32 cm (12.6 inches). Programs should look for mono-skis with fore/aft adjustments in increments that will accommodate a variety of body shapes and sizes. It is also important to know how easily the adjustment can be made and readjusted on the ski slope.

Inclinometer. A simple tool used to measure the ski's angle, the inclinometer is necessary for lateral adjustment of center of mass and measurement of left/right angulation for canting in setting up your mono-ski. You can purchase an inclinometer from Sears (part #9GT3984) for about $15.

Knee-support Height. Knee height determines thigh angle. Set knee height and thigh angle to accommodate your functional balance: The less upper-body stability, the higher the knee height. Adjustment of knee-support height should enhance function, not accommodate the skier's size. A separate strap around the front of each knee should lock the skier's pelvis back into the seat. A single strap around the front of both knees allows the knees and hips to move inside the strap.

Lateral Adjustment. This is the ability to adjust the seat position left and right on the mono-ski frame. Lateral adjustment (not to be confused with canting) can be done at the ski or at the seat and is used to adjust the skier's center of mass laterally over the ski.

Lateral Trunk Stability. People with higher spinal-cord injury (SCI) lesions who cannot control lateral stability will need to adapt the seating system to support their torso without overly limiting movement. Paras (T10 and above) have successfully used rubber inner tubes and fiberglass spring rods to extend the seat back and give them upper-body support. A chest harness made with bungee-cord or inner-tube material can also provide stability, and some harnesses interface with single and double flexible fiberglass rods behind the spine, allowing users to flex forward and to the side, then spring to an upright position.

Lifting Points. Lifting points are usually located near the seat and are used to assist with loading and righting fallen skiers. Mono-skis used for racing do not always have lifting points.

Midcord. The midcord is the middle of the ski. Measure the straight-line distance from the tail to the tip of the ski and divide this distance in half. Then measure that distance from the tail of the ski.  This is the midcord. For adjusting the ski position, it's important to know where you want the midcord position of your ski relative to the ski frame. (See "Setting Up Your Mono-ski, Part 1:  Adjusting the Fore/Aft Position of the Skier's Center of Mass Over the Ski.")

Mounting Plates. Mounting plates are used to attach the mono-ski to the ski. Many ski manufacturers now use standard bindings to do this. A serious racer will need spares and should find out how long it takes to change the ski. 

Orthosis. This device assists body functioning by providing external bracing or support to limit or facilitate proper range of motion (ROM).

Outriggers. The simplest outriggers are forearm crutches with short ski tips attached to the ends; those custom-made are usually lighter. Outrigger cuffs are stainless steel or plastic and can be flexed to make them smaller or larger. If cuffs open on the inside of the arm, they can more easily peel off in a fall. Almost all outriggers have flip locks that allow ski tips to flip up so skiers can use the tail of the ski to push around. Sometimes a steel claw or ice screws are attached to the tail of such skis. Limiting the pivots of the ski tip improves ability to use the tail of the outrigger as a brake; the amount of pivot in the outriggers can be increased as less braking is needed. The outrigger angle should be set so it runs smoothly along the snow. A mono-skier should avoid touching the tail of a rigid ski on snow at high speed. Look for outriggers that have a handgrip mounted at a forward angle. This is the wrist's natural resting position and is more functional and comfortable than a right-angle handgrip.

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