Although the invention pertains both to skis and snowboards, for convenience of discussion reference will be limited hereinafter to skis, it being understood, however, that the same principles disclosed are applicable to snowboards as well.

2. Prior Art It is well known that ski performance involves control of the longitudinal flexibility and torsional rigidity of the ski. As a ski passes over uneven terrain, it is desirable that it flex longitudinally. However, to negotiate turns, the ski must have sufficient torsional rigidity so that its edges can carve into snow to cause the ski to turn. It also is known that vibration and shock transmitted to the skier's legs can be reduced by a laminated ski construction wherein one or more of layers, or partial layers of a lamination consists of an

elastomeric material. An example is the ski disclosed in U.S. Patent 4,405,149.

In U.S. Patent Nos. 5,344,176 and 5,413,371, and in Swiss Patent 0104105, elastomeric materials, alone or in combination with solid materials, are secured to the upper surface of a conventional ski in spaced relationship between the ski and its binding. One purpose of such construction is to elevate the skier above the ski to improve the skier's turning leverage. Additionally, the elastomeric material serves to damp vibrations encountered as the skis are used, such damping being achieved without significantly affecting the ski's flexibility.

Such "add-on" devices add weight and some stiffness to the ski, and they can interfere with the ski binding's function.

SUMMARY OF THE INVENTION The present invention provides a high performance ski construction which nevertheless permits increased longitudinal flexibility and greatly enhanced vibration damping, as compared with known skis, without increasing the ski's weight. This is accomplished by forming the ski with upper and lower segments, and providing a thick layer of low density elastomeric material between the two segments, the layer containing at

least one insert of substantially non-resilient material extending across the width of the ski which maintains the ski's torsional rigidity.

Such a ski construction additionally permits ski bindings to be mounted above the upper surface of the upper segment so as to elevate the skier, thereby reducing boot drag and improving the skier's turning leverage.

BRIEF DESCRIPTION OF THE DRAWINGS The invention now will be described in greater detail with respect to the accompanying drawing, wherein: Figure 1 is a side elevational view of a ski constructed in accordance with the present invention; and Figure 2 is a side elevational view of a further embodiment of a ski constructed in accordance with the present invention.

DETAILED DESCRIPTIONS OF PREFERRED EMBODIMENTS OF THE INVENTION The present invention improves ski performance through a unique lamination arrangement which is illustrated in the accompanying Figure 1 and which now will be described.

A first lower ski segment 10 of conventional construction, but of lighter weight

and greater flexibility, is provided with a layer of elastomeric material 12 interposed between lower segment 10 and a second upper ski segment 14. The upper segment 14 is long and strong enough to serve as a surface for securing the bindings which retain the skier's boot and to provide torsional and longitudinal stiffness, as well as vibration control, to lower segment 10.

The length of the upper segment 14 and elastomeric layer 12 is selected so as to be between 35 and 80% of the overall length of the lower ski segment 10. To achieve the desired characteristics, the material used as layer 12 preferably is an elastomeric foam having a density between 5 and 35 pounds per cubic foot, the most desirable density being approximately 25 pounds per cubic foot. The thickness of layer 12 preferably is in the range of 0.100 - 0.400".

Through appropriate selection of the thickness of segment 14 a division of ski stiffness can be achieved between the upper segment 14 and lower segment 10. That division of stiffness preferably has a ratio of approximately 10:90 to as much as 75:25 (top to bottom). By so arranging the upper and lower segments to be significantly independent of one another, a substantial damping of vibration and shock forces to the skier's legs occurs thereby making the ski

more comfortable and precise to use, especially on icy surfaces. Such damping typically is from 3 to 3 1/2 times greater than in conventional skis or 2 1/2 to 3 times greater than conventional skis used in combination with so-called damping plates such as described in U.S. Patent No. 5,413,371 or Swiss Patent 0104185. At the same time, the longitudinal flexibility of the compound ski is softer than conventional skis so as to permit the ski to better conform to the contour of the terrain over which the ski passes. This is because the enhanced damping and extended control provided by the upper ski segment 14 combine to force the extremities of the ski to hold on the ice with extra tenacity.

As stated previously, it is extremely important that the torsional characteristics of the ski be controlled so that proper edging can be achieved for negotiating turns. In order to retain the desired torsional characteristics of the ski, at least one substantially non-resilient, high density insert 16 is embedded in the low density elastomeric layer 12, insert 16 extending over the full width of layer 12. Such an insert preferably is made of hard rubber having a density of greater than 40 pounds per cubic foot.

If one insert 16 is used, it preferably is positioned within layer 12 between the

locations of the toe and heel pieces of the bindings. When two spaced inserts are incorporated within layer 12, they preferably are positioned below the binding's toe and heel pieces, respectively. It has been found that with one or a multiple of inserts 16, a ski can be produced having outstanding damping characteristics, combined with softened longitudinal flexibility, while maintaining the desired degree of torsional rigidity.

The torsional characteristics of the ski also can be established, if desired, by varying the compressibility of the elastomeric foam layer 12 transversely to the longitudinal axis of the ski. More particularly, a higher density foam, having a density of at least 50 pounds per cubic foot, can be employed on the inside edge of layer 12. i.e., that portion of layer 12 closest to the inside edge of the ski. Of course, this alternative is not applicable to a snowboard.

Torsional characteristics additionally can be achieved by varying the density of the elastomeric material of layer 12 in the direction of the ski's longitudinal axis. In such a case, the material is selected so as to be of higher density at its center than at the ends of layer 12. The highest density area again is greater

than 40 pounds per cubic foot, preferably approximately 60.

In the embodiments discussed above, the ski's characteristics are fixed during manufacture. However, it also is possible to provide an adjustability feature to permit the skier to vary the stiffness and damping of the ski during use. This is accomplished (Fig. 2) by the use of a conventional friction plate 18 at one or both ends of the upper ski segment 14. The friction plate is secured to the lower ski segment 10 and rests on the upper surface of upper segment 14. An adjusting knob 20 bears on the plate to clamp layer 14 to lower segment 10 to a degree dependent on the adjustment of the knob. By this arrangement, the energy absorption contributed by layer 12 can be altered thereby varying the overall stiffness characteristic of the composite ski.

The invention just described provides a ski construction having a high degree of damping and soft feel without the loss of torsional rigidity. The substantial thickness of combined layers 12 and 14 also results in the elevation of a skier's boot which allows improved edge control and reduced boot drag during turns. Since the upper and lower segments 14 and 10 of the ski can flex independently and have high damping, the ski

flex through the boot mounting area thereby permits very short skis to be made while maintaining an adequate boot mounting capability.

An additional advantage of this invention is that the increased thickness of the total ski allows the use of a much narrower lower ski (segment 10). This is because the boot and binding are displaced upwardly high enough to allow high edge angles of the ski without encountering boot or binding drag. This reduction in width further enhances the performance of the composite ski on ice because less twisting torque is required to place the ski on its edge.