WO2007014858A2 - Cross-country ski with wheels - Google Patents

Abstract

A cross-country ski with wheels generally has a chassis with a middle beam and two supports for wheels, one being located in front of the middle beam and the other at the rear. A front wheel is mounted on the front support and at least one rear wheel is mounted on the rear support. The front support has an articulation situated in front of the front wheel whereby permitting the front wheel to pivot about an axis located in a longitudinal plane and vertical with regard to the cross-country ski with wheels.

Description

 WHEEL-BASED SKIING

Technical area

The present invention generally relates to a cross-country ski with wheels, for the practice of cross-country skiing on non-snow-covered terrain.

State of the art

[0002] A conventional cross-country ski includes a central beam, a wheel respectively at the front and at the rear of the central beam and a device for fixing cross-country ski boots.

Normally, cross-country skiing is practiced on roads with a relatively smooth surface. Indeed, a classic cross-country ski is not very suitable for wood paths or bumpy paths. The wheels are generally small, the risk they block is considerable. In addition, with traditional cross-country skis, the skier takes the turns by lifting one of his skis to give it a different direction. To apply this technique on the fly requires some experience. In addition, it is not always suitable on a slightly rough ground because the skier hesitates to lift a ski.

Another problem encountered by the athlete during the practice of cross-country skiing is that of braking. The patent application FR 2 627 995 describes a roller ski comprising on the rear wheel a cable traction brake. A gripping ring is attached to the skier's belt by means of an elastic cable. To brake, the skier grasps the grip ring and pulls on the brake cable. The fact that you need to put a belt and that the braking cables hang freely next to the legs creates a certain inconvenience. In addition, to brake, the skier must use his hands that already hold the ski poles. A grip on the ring is difficult, because he has to focus at the same time on the coordination of the sticks. Object of the invention

An object of the present invention is to provide an improved cross-country ski. This object is made by a cross-country ski as claimed in claim 1.

General description of the invention

A cross-country ski with wheels generally comprises a frame with a central beam and two supports for the wheels, one at the front of said central beam and the other at the rear. A front wheel is mounted on the front support and at least one rear wheel is mounted on the rear support. Note that the presence of a pair of rear wheels increases the stability of the wheeled ski, which will appreciate a beginner skier or one who wants to practice cross-country skiing on unpaved roads. On the other hand, a cross-country ski with only one rear wheel has the advantage of having less resistance to advancement and thus allows faster locomotion. In addition to the parts described so far, a classic cross-country ski includes a fixing device on the central beam to receive a cross-country ski boot. The fastening device allows the skier in particular to lift his heel, which constitutes an additional fundamental difference between a cross-country ski with wheels and a roller skate. According to an important aspect of the invention, the front support has a hinge arranged in front of said front wheel allowing the front wheel to pivot about an axis contained in the longitudinal and vertical plane relative to the cross-country ski. This axis may itself be substantially vertical or, as according to a preferred embodiment of the invention, be inclined forward with respect to the vertical by an angle of between 5 to 45 degrees, preferably between 15 and 35 degrees. . A cross-country ski with wheels according to the present invention therefore has the advantage of a directional front wheel. With a classic cross-country ski, a skier must take the turns in stages of lifting one of his skis to give him another direction than the ski on the ground. Because in a roller ski according to the invention the front wheel is pulled, the user can turn by keeping one or both skis on the ground, by simple shifting his weight on the side to which he wants to turn. Naturally, for example to take tighter turns or turn on the spot, it is always possible to turn in a classic way. In addition to the simplified cornering technique, the front wheel increases ride comfort, especially on rougher terrain. Thanks to its steerability, the front wheel can avoid small stones that are in its path. Therefore, a directional wheel is less likely to block completely, which could cause the skier to fall. A wheeled cross-country ski even better adapted to a bumpy terrain advantageously comprises wheels with a larger diameter, for example from 10 to 15 cm.

More specifically, the front support may comprise a frame rigidly connected to the central beam with two lateral sides which pass on one side and the other of the front wheel and which join before it. On the side of the central beam, the frame preferably has a width greater than central beam. The frame width decreases towards where the sides of the frame join in front of the wheel. The wheel itself is mounted on a wheel holder (eg a fork piece or link), which is connected to the frame by the hinge allowing the wheel to pivot. The lateral sides of the frame make it possible to limit the pivoting movement of the front wheel. As the width of the frame decreases towards the front, the latter presents, seen from above, a shape resembling a drop or a triangle. The front wheel can rotate at an angle corresponding to the angle formed between the two lateral sides of the frame. The latter is preferentially around 15 degrees. To further increase comfort, the front support has a shock absorber at the joint. A shock absorber will be particularly appreciated on wooden roads or on deteriorated roads. Obviously, the rear wheel support may also be equipped with a shock absorber. For even more comfort and optimized shock absorption, the wheels are advantageously inflatable. To prevent the front wheel from striking the frame during a turn, the wheel holding member may comprise stops cooperating with the two side sides of the frame. The pivoting movement of the front wheel is thus limited. The stops may be adjustable to allow the user to choose the maximum angle that can form the wheel with the longitudinal axis of the ski.

Advantageously, the front support comprises recentering means for the front wheel. These recentering means may resiliently oppose the inclination of the front wheel relative to the longitudinal axis of the ski and pull or push in the position where it is aligned with the ski. The recenter means may be arranged at the joint, but in a preferred embodiment of the invention, the recentering means comprise springs arranged between the frame and the fork member of the front support. It should be noted that if the axle of the articulation of the front wheel-holding piece is inclined forwards, the user can control the steering and also the refocusing of the front wheel by changing the lateral inclination of his skis.

The frame may comprise reinforcing means, such as sheets or rods, passing above the front wheel.

A first embodiment of the present invention also provides a brake of a particular design for a cross-country ski. The proposed braking device comprises a braking pad that can act on the rear wheel (s), a brake cable and a brake control lever. The latter is arranged so that it can be actuated by the shin of a user of cross-country skiing. Upon actuation of the brake control lever, the brake cable is tensioned to engage the brake pad in a braking position. An improved brake for a cross-country ski is provided by the present invention. The brake allows the user to brake without having to move into an unstable position. He does not need to use his hands to operate the brake. The fact that the skier can use his ski poles to balance out significantly reduces his risk of falling. Preferably, the brake control lever can be actuated by a movement in front of the shin of the user. To brake, the skier flexes his knee and his shin pushes the brake control lever forward. At the same time as braking, the user therefore lowers its center of gravity which gives it greater stability.

According to a preferred embodiment of the invention, the brake control lever can tilt forward when the skier raises the heel without the brake pad is thus engaged in a position of braking. In the technique of cross-country skiing, the skier lifts the heel of the foot momentarily at the back. The leg thus descends obliquely to the rear and is thus likely to actuate the brake control lever if it does not follow the movement of the leg. Because the brake control lever can tilt forwards when the bead is raised without engaging the pad in a braking position, the skier can ride regardless of his or her touching the brake control lever. To allow tilting of the brake control lever, the braking device may include means for reducing the tension of the braking cable when the skier's heel is raised.

Advantageously, the braking device comprises a spring which, when the brake control lever is not actuated, holds the brake pad in a rolling position and exerts a tension on the braking cable to straighten the lever. brake control. The rolling position is defined as the position of the parts of the braking device which does not prevent the wheel from rotating freely. According to another preferred embodiment of the invention, the braking device comprises a brake lever, a braking pad, a braking cable and an actuator, said braking lever carrying the braking pad and being connected. to the actuator by the braking cable, the actuator can be moved into a braking position in which it pulls the braking cable by movement forward of the knee of the skier. Advantageously, this actuator includes a winder which is attached to a strap which can be attached to the skier's knee and unrolled from said retractor. The actuator is in this case fixed to the frame so as to be rotatable relative to a transverse horizontal axis, the strap causing a tilting of the actuator in the braking position when it is essentially unwound, that is to say say when fully unwound and / or, in the case where the retractor comprises a strap return spring, when the force transmitted to the actuator by the return spring exceeds the initial tension of the braking cable. Preferably, the braking device comprises adjustment means allowing the skier to adjust the length of the strap according to his needs. The braking device of this embodiment essentially has the advantages of the embodiment described above. Compared to the latter, however, it requires fewer moving parts and forms a simpler mechanism therefore potentially cheaper to manufacture. It should be noted that the word strap designates in this context any kind of cable, string, etc., preferably substantially inelastic.

According to an advantageous aspect of the invention, the rear wheel support comprises a truck (axle eg for skateboard) damping by elastomer or, preferably, by springs. The frame preferably comprises a portion raised relative to the central beam to which the truck is attached. Advantageously, the raised portion is connected to the central beam via a curved or oblique transition piece, which confers, in addition to an elegant appearance to the ski.

Those skilled in the art will note that a cross-country ski with a brake as described herein does not necessarily need to be equipped with a directional front wheel.

The total length of the cross-country ski is preferably between 60 and 90 cm, and more preferably between 60 and 70 cm. A short ski has a lower moment of inertia, which facilitates the practice of the sport and increases its attractiveness. With the swivel wheel, the directional stability of the ski is not jeopardized by the shortening of the ski. It will be noted that the cross-country ski may have a mechanism for varying the length, e.g. ex. a beam central telescopic. Each user can thus adjust the length of the ski according to his own needs.

Brief description of the drawings

Other features and features of the invention will become apparent from the detailed description of various advantageous embodiments presented below, by way of illustration. Reference is made to the accompanying drawings, which show:

Fig. 1: a longitudinal view of a support of the front wheel; Fig. 2: a horizontal view of the device of FIG. 1; Fig. 3: a longitudinal view of a braking device of the rear wheel when the skier actuates it;

Fig. 4: a longitudinal view of a braking device of the rear wheel when the skier does not actuate the brake but keeps the heel in contact with the ski; Fig. 5: a longitudinal view of a braking device of the rear wheel when the skier lifts the heel;

Fig. 6: an isometric view of a preferred embodiment of a cross-country ski with wheels;

Fig. 7: a side view of the wheeled cross-country ski of Figure 6; Fig. 8: a top view of the wheeled cross-country ski of Figure 6; Fig. 9: a view from below of the cross-country ski with wheels of FIG. 6;

Fig. 10: a longitudinal section of the front wheel support of the cross-country ski of Figure 6;

Fig. 11: an isometric view of a detail of the braking device of the wheeled cross-country ski of FIG. 6. Description of preferred embodiments of the invention

[0022] Figure 1 shows a longitudinal view, Figure 2 a horizontal view of a support 10 of the front wheel 12 of a cross-country ski wheel according to a first embodiment. The support 10 comprises a frame 16, a fork piece 18 and a hinge 14, arranged at the front of the wheel 12, which connects the frame 16 to the fork piece 18. The wheel 12 is mounted on the fork piece so as to freely rotate about its axis 34. With the hinge 14, the fork piece 18 can, together with the wheel 12, pivot about the axis 20 passing vertically by the hinge 14. The piece fork 18 is held movable relative to the frame 16 by ball bearings 22, 24. The frame 16 is suspended from the fork member by means of a spring 26. A pin 28 is housed on the axis 20 of the hinge 14 and attached to the fork member 18. At the lower end, the pin 28 has a thread for screwing a nut 30. The ball bearing 24 rests on the nut 30 and serves as a support for the spring 26 The other side of the spring 26 bears against the ball bearing 22 and presses it against the upper wall 1e of the cylindrical housing 32, which is integral with the frame 16. The ball bearing 22 serves as a guide for the pin 28, which can perform a reciprocating movement relative to the cylindrical housing 32 to dampen shocks. A stop 36, comprising for example a polyethylene or Teflon washer, is arranged between the upper wall of the housing 32 and the fork piece 18, to prevent these two parts from colliding when the wheeled ski is not or little loaded. The abutment 36 advantageously comprises another ball bearing for reducing the friction between the cylindrical casing 32 and the fork piece 18. [0023] The wheel 12 is preferably an inflatable wheel with a diameter of 10 to 15 cm. A higher wheel size makes it easier to ride on uneven ground where wheels with a normal diameter (6 to 8 cm) would block. To avoid that with wide wheels the skier is too far from the ground, the frame 16 is located below the axis 34 of the front wheel. It should be noted that the greater the distance from the ground to the foot, the more difficult it is to remain balanced on the ski. In addition, the risk of the skier stepping on his foot during a fall increases with the distance from the ground. Seen from above, the frame 16 has a shape resembling a drop. The width of the frame 16 at the rear of the wheel 12 is greater than the width of the central beam 15. The pivoting movement of the wheel 12 is limited by the angle formed between the two lateral sides of the frame 16. This angle is preferably between 10 and 15 degrees.

The fork piece 18 goes down from the hinge 14 to the axis 34 of the front wheel 12. Beyond the axis 34, relative to the joint, the arms of the fork piece is extend to form abutments 36. These abut against the frame 16 to limit the pivoting movement of the wheel 12 about the axis 20. The abutments 36 may comprise a buffer of elastic material to absorb the shock when the stops hit the frame 16.

To refocus the wheel 12, springs 38, 40 are arranged on both sides of the wheel 12 between the fork piece 18 and the frame 16. In a right turn, the rear of the wheel 12 leaves towards the left. The left spring 38 is compressed and the right spring 40 is stretched. The springs 38, 40 therefore contribute to recentering the wheel 12 until it is again aligned with the central beam 15.

Figures 3, 4 and 5 show a longitudinal view of the rear part of the cross-country ski with wheels. At the rear of the central beam 15, a support 41 of the or rear wheel 42 is fixed to the central beam 15. The cross-country ski has a braking device with a brake pad 44, a braking cable 46 and a brake control lever 48. When a force 50 is exerted on the lever 48, the cable 46 is stretched and the brake pad comes into contact with the wheel 42. [0028] The brake control lever 48 is so arranged on the central beam 15 of the frame that it allows the skier to brake with the tibia 64. At or near the central beam 15, the lever 48 is mounted on a substantially horizontal axis 52 and transverse, which allows the upper part of the lever 48 to pivot forward. The shaft 52 is housed held in a support piece 66 so as to slide obliquely relative to the direction of the bearing. For this purpose, the support piece 66 has holes oblong 68 inclined relative to the horizontal in which the axis 52 can slide. In a variant of this embodiment, the axis 52 is fixed to the support piece 52, and the oblong holes 68 are present on the brake control lever 48. The attachment 70 makes it possible to fix a shoe cross-country skiing 72 to the central beam 15 movable about an axis 74 located at the front of the shoe 72 so that the skier can lift the heel. The attachment 70 is further provided with a deflection member 76 which deflects the braking cable 46 to an attachment point 54 on the brake control lever 48. The cable 46 is deflected by a pair of pulleys deflection 56 and returned to the rear wheel 42 through a hollow space in the central beam 15. Another deflection pulley 58 returns the cable 46 to a brake lever 60, which comprises the brake pad 44.

To brake, the skier flexes the knee while keeping the heel in contact with the central beam 15 (Fig. 3). The tibia 64 then pushes the top of the lever 48 forward. The attachment point 54 is moved forward which increases the distance between the deflection member 76 and the attachment point 54. Simultaneously, the axis 52 slides obliquely forward and the boss 78 of the lever brake control pushes on the cable 46. Of these facts, the braking cable 46 is stretched. The pulleys 58, 56 transmit the tension of the cable 46 to the brake lever 60 and the brake pad 44 is brought into contact with the rear wheel 42. A spring 62 between the brake lever and the support 41 is stretched when the brake is actuated.

When the skier releases the pressure on the control lever 48, the spring 62 straightens the brake lever 60 and thus brings the brake pad 44 into the rolling position (FIG 4). At the same time, a tension is created on the cable 46, which brings the brake control lever 48 back into its rolling position: the top of the lever 48 is moved rearward, while the tension of the cable 46 causes the brake to slide. 52 axis rearward in the oblong guide holes 68. To roll, the axis 52 of the brake control lever 48 is held in the upper rear portion of the oblong hole 68 by the tension of the cable 46. When the skier raises the heel, as shown in Figure 5, the deflection member 76 of the fastener 70 tilts forwards and approaches the point of attachment 54 of the cable to the brake control lever 48. The tension on the cable 46 is thus released, which allows the lever brake control 48 to swing forward without the brake being actuated.

When the cross-country ski has two rear wheels 42, they are preferably rotatably mounted on an axle that can pivot about a fixed axis of the central beam and inclined relative to the vertical. With this, the skier can, by the lateral displacement of its weight, tilt the cross-country ski on one side and thus cause a turning of the rear axle, as on a skateboard. Advantageously, this steering device comprises a means for limiting the inclination of the ski and the steering. A preferred embodiment of the invention is illustrated in FIGS. 6 to 11. The cross-country ski with wheels 100 comprises a chassis with a central beam 115, a front wheel support 110 and a rear wheel support. 141. The central beam 115 is formed of a hollow aluminum rectangular profile, connected to the wheel supports 110, 141 by screws or welding. The wheels include tubular tires with a width of 30 mm and a diameter of 122 mm. The wheels, or at least one wheel can be equipped with a rollover bearing, which will facilitate the practice of the sport.

The front wheel support 110 comprises a frame 116, a fork piece 118 and a hinge 114, arranged at the front of the wheel 112, which connects the frame 116 to the fork piece 118. The frame 116 is is in the form of a cage with reinforcing plates 117 passing over the front wheel 112. The junction 119 of the frame 116 with the central beam 115 is formed by interlocking. The holding in position is performed by screw-tightening through the central beam 115, with inserts in the frame 116. [0037] The front wheel 112 is mounted on the fork member 118 so as to be freely rotatable about its axis 134. With the articulation 114, the fork piece 118 may, together with the wheel 112, pivot about the axis 120. The pivot axis 120 is contained in the vertical longitudinal plane of symmetry of the cross-country ski 100 and inclined 30 degrees to the before. Because the pivot axis is inclined forwards with respect to the vertical, the front wheel 112 tends to align with the ski when the skier keeps the central beam 115 horizontal, that is, say when he does not impose lateral inclination. Stoppers 136 arranged on the axis of rotation 134 of the front wheel 112 limit the pivoting movement of the front wheel 112 because they bear on the lateral sides of the frame 116. As shown best by Figure 10, the fork member 118 comprises a cylindrical housing 180 arranged around the axis 120 of the hinge 114. The carcass 180 houses a shaft 181 fixed to the frame 116 of the front wheel support. The shaft 181 ends in a stop 182, formed, in this embodiment, by a thick washer screwed onto the shaft 181. The cylindrical casing 180 has, on the lower side, a portion 183 with a reduced internal diameter forming a stop. The rotation of the shaft 181 in the cylindrical carcass 183 is facilitated by a ball bearing 184 and a bearing 185 housed between the abutment 183 of the carcass 180 and the shaft 181. To dampen shocks, an elastomer ring 186 is arranged between the ball bearing 184 and the stop 182 of the shaft 181. The hardness of the elastomer ring 186 can naturally be chosen according to the weight of the skier. The shaft 181 and the cylindrical casing 180 are preferably made of steel. Lubrication of the assembly is made possible by the passage of screw 187, which is closed off by a plastic cover 188. [0039] The rear wheel support 141 of the cross-country ski 100 includes a truck 145, on which are mounted the Rear wheels 142. Trucks suitable for use in the present invention exist on the market as standard parts and do not in principle require a detailed description. In the illustrated embodiment, we chose a spring-cushioned aluminum truck, but we could obviously choose an elastomer damped truck. In general, the greater the angle formed between the axis of the springs and the vertical, the more the truck is manageable. In the present case, we chose an angle of 45 degrees. The distance between the rear wheels is 105 mm. The portion 143 of the rear wheel support 141, through which the truck 145 is fixed to the chassis, is raised relative to the central beam 115. The junction between this portion and the central beam comprises an oblique transition piece 147, preferably made in the same material as the central beam 115, and lateral reinforcing plates 149 which increase the stability of the junction.

The cross-country ski is provided with a braking device acting on the rear wheels. The braking device comprises brake pads 144 mounted on a brake lever 160 which serves to put the brake pad 144 in contact with the wheels 142. The brake lever 160 is actuated by a braking cable 146 passing through a sheath below the oblique transition piece 147. The brake cable 146 is attached at its other end to a brake actuator 190 placed on the central beam 115 at the rear of the area where the skier's foot rests. The brake actuator 190 can rotate on a transverse horizontal axis 191 to pull on the brake cable 146 and actuate the brake. The actuator 190 is connected to the user's leg by a strap 192 attached, on the one hand, below the knee of the skier and, on the other hand, to the actuator. The strap is fixed on the actuator by means of a winder 193. When the skier pulls on the strap 192, the strap first unrolls without the actuator 190 pulling on the brake cable 146. If the strap 192 is fully unwound, pulling more on the strap 192 causes the actuator 190 to tilt about the axis 191 and thus the actuation of the brake. The retractor 193 is provided with a spiral return spring 194 to keep the strap 192 stretched at all times and thus prevent the latter from dragging on the ground or interfering with other components of the cross-country ski with wheels 100. It has already been said that during normal advancement (without braking), the skier raises the heel of the foot of the leg momentarily to the rear. The length of the strap 192 and the wound length of the strap 192 are adjustable so that the heel lifts do not cause braking. If he wants to brake, the skier bends his knees and therefore pulls more on the strap 192 than if he raises the heel. The wound length of the strap 192 is adjusted so that the strap 192 is fully unwound before the skier's knee is in its extreme position during braking. Thus, it is ensured, on the one hand, that the brake is reliably actuated when the skier takes the braking position and, secondly, that the brake is triggered only under this condition. Of course, the proper wound length of the strap and the total length of the strap can vary from person to person. Finding these good lengths for an individual is however routine work for the skilled person. Preferably the braking device comprises adjustment means for adjusting these parameters.

Claims

claims A wheeled cross-country ski comprising a frame with a central beam, a front support at the front of said central beam on which is mounted a front wheel and a rear support at the rear of said central beam on which is mounted at less a rear wheel; characterized in that said front support has a hinge in front of said front wheel allowing said front wheel to pivot about an axis contained in a longitudinal and vertical plane with respect to the cross-country ski with wheels. 2. A cross-country ski as claimed in claim 1, wherein the axis about which the front wheel is pivotable is inclined forwards with respect to the vertical by an angle of between 15 and 35 degrees. 3. A cross-country ski as claimed in claim 1 or 2, wherein said front support comprises: a frame rigidly connected to said central beam, having two lateral sides which pass on either side of said front wheel and which join in front of said front wheel, said frame having, on the side of the central beam, a width greater than said central beam and the width of said frame decreasing towards where said sides join; and a wheel holding member connected by said hinge to said frame, on which is mounted said front wheel. 4. A cross-country ski as claimed in claim 3, wherein said front support comprises a shock absorber at said hinge. 5. Cross-country skiing according to one of claims 3 to 4, wherein said support comprises means for refocusing the front wheel. 6. Cross-country skiing according to one of claims 3 to 5, wherein the recentering means comprise springs arranged between said wheel holding member and said frame. 7. Cross-country ski according to one of claims 3 to 6, wherein the frame comprises reinforcing means passing above the front wheel. Wheeled cross-country ski according to one of claims 1 to 7, comprising a braking device with a braking pad acting on said rear wheel (s), a brake cable and a brake control lever which can be actuated by the tibia of a user of said wheeled downhill ski, wherein the brake cable can be tensioned by actuation of said brake control lever to engage said brake pad in a braking position and wherein said control lever brake can be actuated by a movement in front of the shin of the user. 9. Wheeled cross-country ski according to one of claims 8 to 9, comprising a fixing device on the central beam for receiving a cross-country ski boot and allowing a skier to raise the heel, wherein said brake control lever can tilt forwards when the skier raises the heel without the braking pad being thereby engaged in a braking position. A cross-country ski as claimed in one of claims 8 to 10, wherein said braking device comprises a spring which, when said brake control lever is not actuated, maintains said braking pad in a rolling position and exerts a tension on said brake cable to rectify said brake control lever. Wheeled cross-country ski according to one of claims 1 to 7, comprising a braking device comprising a brake lever, a braking pad, a braking cable and an actuator, said braking lever carrying the braking pad and being connected to the actuator by the braking cable, the actuator can be moved into a braking position in which it pulls on the braking cable by movement forward of the knee of the skier. The wheeled cross country ski as claimed in claim 11, wherein said actuator comprises a retractor to which a strap is attached, said actuator being fixed to the frame so as to be rotatable relative to an axis. horizontal transverse, said strap being attachable to the knee of a skier and unrolled from said reel so as to cause a tilting of the actuator in said braking position by pivoting about said horizontal transverse axis when the strap is essentially unrolled. 13. A cross-country ski as claimed in claim 12, wherein said retractor comprises a web return spring. 14. A cross-country ski as claimed in claim 13, wherein the braking device comprises adjusting means for adjusting the length of the strap. 15. A cross-country ski as claimed in any one of the preceding claims, wherein the rear wheel support comprises a spring-damped or elastomeric truck. Wheeled cross-country ski according to claim 15, wherein said chassis comprises an elevated portion with respect to the central beam, said truck being attached to this raised portion. The cross-country ski of claim 16, wherein said raised portion is connected to the central beam via a curved or oblique transition piece.