Patent Publication Number: US-2013234417-A1

Title: Ski binding witih boot-center referencing

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon French patent application Ser. No. 12/00718, filed Mar. 9, 2012, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is claimed under 35 U.S.C. §119. 
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a device for binding articles of footwear on a gliding apparatus. In a particular example, the invention relates to a binding device for retaining a boot on a ski, such as an alpine ski boot on an alpine ski. The invention also embraces other examples of bindings for boots. 
     2. Background Information 
     To achieve optimal gliding performance, whether for skis or other gliding apparatus, positioning the athlete&#39;s boot or other article of footwear in relation to the gliding apparatus is important. This positioning is directly defined by the footwear binding device. In alpine skiing, it is common to refer to the boot center in order to position the binding device properly on the ski. The term “boot-center” generally refers to the middle of the standardized length of the sole of an alpine ski boot. Thus, it is typical to have a reference mark, referred to as the “boot-center”, on the ski. The reference mark is determined, following tests, to indicate to the assembly operator the location at which the binding device should be positioned so that, when the ski boot is engaged with the binding device, the boot-center of the ski boot is substantially aligned with the “boot-center” reference mark of the ski. With this configuration, the skier enjoys the best performance of his/her skis in normal alpine skiing situations. 
     Notable hereinafter are the term “binding boot-center”, which refers to the position of the boot-center of the ski boot in relation to the ski, such position being obtained via a predetermined adjustment of the binding device, and the term “ski boot-center”, which refers to the position of the reference mark, on the ski, of the recommended location of the boot-center that makes it possible to obtain good ski behavior under certain conditions. 
     For some alpine skiing disciplines, it may be advantageous not to align the binding boot-center with the ski boot-center. In this case, the binding is configured to offset the binding boot-center forward or rearward in relation to the ski boot-center. For example, offsetting the binding boot-center toward the front of the ski can improve handling at the expense of stability. In this configuration, the ski tends to turn more easily. Conversely, offsetting the binding boot-center toward the rear of the ski can be beneficial to stability when the skier travels down slopes in powdery snow, thus reducing the risk of tipping forward. Nevertheless, the offset should be measured, because an excessive offset can have a negative effect. Thus, the skier can adjustably set the boot position in relation to the ski as a function of the desired sensations, the intended skiing discipline to be practiced, for example on a groomed slope or powder snow. The effect of this offset between the binding boot-center and the ski boot-center is all the more pronounced as the “contact length” is short, that is to say, the length of the ski sole area in contact with the snow is reduced. 
     Generally speaking, binding devices are assembled to the ski using a jig template that is positioned in relation to the ski “boot center” reference mark. The jig template makes it possible to drill holes into the board for the screws used to fix a front retaining element, or toe-piece, and a rear retaining element, or heel-piece. In the case of a binding provided with non-adjustable retaining elements, this step is crucial as it will characterize the behavior of the ski during use. To be more versatile, a number of binding devices comprise devices for adjusting the position of the toe-piece and/or of the heel-piece in relation to the ski. In addition to adapting a binding to a predetermined boot size, the aforementioned adjustment devices also make it possible to adjust the binding boot-center. 
     In general, the known adjustment devices can be categorized by a first group enabling the toe-piece and/or the heel-piece to be adjusted individually, a second group enabling the toe-piece and the heel-piece to be adjusted simultaneously, and a third group enabling the position of a sub-assembly including the toe-piece and the heel-piece to be adjusted. 
     When an alpine ski is equipped with adjustment devices of the first group, adjusting the spacing between the toe-piece and the heel-piece of the binding offsets the binding boot-center with respect to the ski boot-center. To compensate for this offset, the user can manually correct it through iteration of the adjustment of the position of the toe-piece and of the heel-piece, respectively, in order to maintain the desired relative position between the binding boot-center and the ski boot-center, only if the positions of the toe-piece and of the heel-piece are adjustable. Specifically, each iteration involves mounting the alpine ski boot on the binding, and then observing the relative position between the actual boot-center indicated by a reference mark on the sole of the boot and the ski boot-center. If there is a difference compared to the target value, the boot is removed, and the toe-piece and heel-piece are then moved by the same distance, in the same direction. Then, the user repeats the previous operation until achieving the desired adjustment. Although the first group of adjustment devices mentioned above clearly enables an adjustment of the binding boot-center in relation to the ski boot-center, such an adjustment is complicated, time consuming, and inaccurate, because it requires iteration of the adjustment of the positions of the toe-piece and of the heel-piece. In addition, this adjustment requires using a boot of the targeted size, which further complicates the work of the assembly technician. Indeed, the right boot size useful for this configuration operation is not necessarily available to the assembly technician when adjusting the binding. 
     When an alpine ski is equipped with an adjustment device of the second group, adjusting the spacing between the toe-piece and the heel-piece of the binding does not normally offset the binding boot-center in relation to the ski boot-center, given that the toe-piece and the heel-piece move symmetrically, away from or closer to one another. However, due to its operating principle, this second group of adjustment devices suffers from the disadvantage of not enabling the binding boot-center to be adjusted in relation to the ski boot-center. A binding of this type is therefore suitable for modifying the size adjustment of a binding, which is desired, for example, for bindings intended for rental. This type of binding is therefore limited to the relative position between the binding boot-center and the ski boot-center that is initially selected, when the binding is being mounted on the ski (with the jig template). Therefore, if one wishes to modify this relative position, it is necessary to dismount the binding before remounting it in a different position, which is a tedious, time-consuming, and expensive operation. In addition, this adjustment requires using a boot of the right size or jig templates, which further complicates the work of the assembly technician, as described above. 
     When an alpine ski is equipped with an adjustment device of the third group, it is then possible to adjust the position of the sub-assembly comprising the toe-piece and the heel-piece. This type of adjustment makes it possible to adjust the relative position between the binding boot-center and the ski boot-center, while maintaining a predetermined spacing and, therefore, an adjustment for a given boot size. However, a binding of this type does not include any reference mark for the binding boot-center. Consequently, the adjustment of such relative position requires mounting a boot on the binding in order to determine the location of the actual-boot center indicated by the reference mark on the boot sole. This type of binding is advantageous, especially if coupled with an adjustment device of the first or second group. However, this type of adjustment requires using a boot, which further complicates the work of the assembly technician, as described above. 
     Therefore, and especially after adjusting the size of the binding, the prior art solutions currently known in the field of ski bindings do not make it possible to adjust the binding boot-center in relation to the ski boot-center in a simple, fast, and accurate fashion. It is particularly desirable to be able to make this type of adjustment, in the case of an adjustment related to a change in size, without it being necessary to insert a boot of the intended new size in the binding, in order to facilitate the work of the assembly technician. In addition, the field of ski bindings would be enhanced if the binding boot-center could be adjusted in a well-defined fashion in a plurality of various positions in relation to the ski boot-center. 
     SUMMARY 
     The present invention overcomes the disadvantages of known ski bindings and achieves the aforementioned advantages. In particular, the invention provides a ski binding offering a simple, fast, and accurate adjustment of the position of the boot in relation to the gliding apparatus and, in particular, of the binding boot-center relative to the ski boot-center. 
     The invention also enables the user to adjust the binding boot-center easily, without requiring the use of a boot. 
     Further, the invention achieves this adjustment by offering a plurality of different but well-defined positions of the binding boot-center in relation to the ski boot-center, so that the user can easily customize the position of the boot on the ski. 
     Still further, the present invention provides a ski binding having an adjustment arrangement that is optimally adapted to achieve the above adjustments, the adjustment arrangement being structurally strong, but also simple, quick in performing an adjustment, and reliable during use. 
     Further still, the invention determines the adjustment of the binding device, and more particularly the adjustment of the binding boot-center in relation to the ski boot-center, simply by observing the gliding apparatus equipped with the binding device. Thus, the user knows, with a glance at the ski, whether the binding is properly adjusted for the skiing discipline considered. 
     To this end, the present invention provides a device for binding an article of footwear on a gliding apparatus, such binding device including a toe-piece and a heel-piece. The device includes a mechanism for indicating a reference point determined by a predefined ratio between the distance between a front reference plane associated with the toe-piece and such reference point, on the one hand, and the distance between such reference point and a reference plane associated with the heel-piece, on the other hand. 
     Through these measurements, the user can easily and quickly adjust any relative positioning between the binding boot-center and the ski boot center, because he/she constantly has an indication of a reference point directly on the ski binding, the reference point corresponding to the ski boot-center, for example. 
     Alternatively, the reference point is not the boot-center but a particular reference mark indicative of a ratio between the distance between one end of the boot sole and this reference mark, on the one hand, and the distance between this reference mark and the other end of the boot sole, on the other hand. In this case, the indication structure must be adapted to identify this ratio when the adjustment of the binding elements is modified. According to this alternative embodiment, the reference point is to be positioned in relation to another specific reference mark of the ski. 
     In addition, the binding device comprises a base affixed to the gliding apparatus, the base having, for example, a scale adapted to identify the positioning of the reference point, indicated by the indication structure, in relation to the base. Advantageously, this scale also makes it possible to describe the positioning of the base in relation to the gliding apparatus and, in particular, in relation to the ski boot-center. Thus, the adjustment of the binding boot-center of the device with respect to the gliding apparatus is easier and more precise. 
     In one embodiment of the device, the first adjustment structure of the device is selected so as to allow adjustment of the longitudinal position of the heel-piece, and the second adjustment structure is selected so as to allow adjustment of the longitudinal position of a subassembly comprising the toe-piece and the heel-piece. Thus, a binding is obtained, having not only a suitable indication of a reference point but also optimally adapted adjustment structure to carry out this adjustment quickly and easily. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Other characteristics and advantages of the invention will become apparent from the dependent claims and the description disclosing the invention in more detail hereinafter, with reference to the annexed drawings schematically showing, by way of example, how the invention is embodied, and in which: 
         FIG. 1  shows a schematic perspective view of the footwear binding device according to the present invention, mounted on a gliding apparatus; 
         FIG. 2   a  shows a top view of the device shown in  FIG. 1 , the spacing between the toe-piece and the heel-piece being adjusted for a first given boot size and the binding boot-center coinciding with the ski boot-center; 
         FIG. 2   b  is a side view of the device shown in  FIG. 2   a;    
         FIG. 2   c  is a longitudinal cross section along the line I-I shown in  FIG. 2   a;    
         FIG. 3   a  shows a top view of the device, similar to  FIG. 2   a , the spacing between the toe-piece and the heel-piece being adjusted for the first given boot size, and the binding boot-center being positioned forward with respect to the ski boot-center; 
         FIG. 3   b  is another top view of the device, similar in  FIG. 2   a , the spacing between the toe-piece and the heel-piece being adjusted for the first given boot size, and the binding boot-center being positioned rearward in relation to the ski boot-center; 
         FIG. 3   c  is another top view of the device, similar to  FIG. 2   a , the spacing between the toe-piece and the heel-piece being adjusted for a second given boot size, and the binding boot-center coinciding with the ski boot-center; 
         FIG. 4   a  shows a top view of the device when a ski boot is positioned on the device, the boot being symbolically represented by a boot sole; 
         FIG. 4   b  is a side view of the device shown in  FIG. 4   a , including the sole, the binding boot-center coinciding with a reference mark on the boot indicating the boot center; 
         FIG. 4   c  is a longitudinal cross section along the line II-II shown in  FIG. 4   a ; and 
         FIG. 5  is a schematic diagram of a structure for indicating a reference point determined by a predefined ratio between the distance between a reference plane associated with the toe-piece and this reference point, on the one hand, and the distance between this reference point and a reference plane associated with the heel-piece, on the other hand. 
     
    
    
     DETAILED DESCRIPTION 
     The invention will now be described in detail with reference to the annexed drawings illustrating, by way of example, various embodiments of the invention. 
     The present invention relates to a device for binding an article of footwear on a gliding apparatus, such gliding apparatus comprising, for example, an alpine ski or a touring ski. Hereinafter, the device will be interchangeably called a boot binding device or a ski binding, or simply a binding. Similarly, when referring to the gliding apparatus, the terms “gliding apparatus” and “ski” will be used interchangeably, without limiting the scope of the corresponding explanations which, in any case, extend to any gliding apparatus. 
     As shown in  FIG. 1 , the boot binding device, according to the first embodiment of the invention, comprises a base  1  adapted to be fixed upon the gliding apparatus and to extend, when mounted upon the gliding apparatus, substantially along the longitudinal axis  1 . 1 , or vertical longitudinal plane, of the gliding apparatus. In the illustrated embodiment, the gliding apparatus is an alpine ski, a longitudinal segment being illustrated, the ski not directly constituting a focus of the invention. 
     Conventionally, the boot binding device comprises a front retaining element  2  or binding, commonly known as the toe-piece, and a rear retaining element  3  or binding, commonly known as the heel-piece. The device also includes first  4  and second  5  sliding racks mounted on the base  1 . These sliding racks  4 ,  5  serve to guide the toe-piece  2  and the heel-piece  3  longitudinally, so that they can move in translation along the longitudinal axis of the gliding apparatus. In the illustrated embodiment, the sliding racks are each formed of two lateral guide elements in which elements of corresponding shape, formed laterally on the lower portions of the toe-piece  2  and heel-piece  3 , can cooperate and slide longitudinally along the ski. For the toe-piece, the lateral guide elements, or rails, forming the first sliding racks  4 , are oriented toward the center of the ski. Conversely, for the heel-piece, the lateral guide elements, or rails, forming the second sliding racks  5 , are oriented outward of the ski. It is clear to one of ordinary skill in the art that any other equivalent structure, such as one or two rods or other similar structure, can replace the guide structure shown, by way of example, in the various drawing figures. Moreover, it is also possible to mount the first  4  and second  5  sliding racks directly on the gliding apparatus, instead of assembling them on a base  1 . The base  1  may be a unitary (i.e., single) piece, or made of a plurality of pieces/portions. In the first embodiment of the binding device illustrated in the drawing figures, the base  1  is comprised of several portions, namely a front portion for the toe-piece  2 , a rear portion for the heel-piece  3 , and an intermediate portion between these two portions used to house the elements positioned between the toe-piece  2  and the heel-piece  3 . 
     To enable the toe-piece  2  and the heel-piece  3  to move longitudinally in a controlled manner, the device comprises a first adjustment mechanism  6  and a second adjustment mechanism  7 . Without departing from the general scope of the present invention, the first adjustment mechanism  6  makes it possible to adjust the longitudinal position of either one of the toe-piece  2  and heel-piece  3  in relation to the gliding apparatus, and the second adjustment mechanism  7  makes it possible to adjust the longitudinal position of either one of the heel-piece  3  and toe-piece  2 , or of a sub-assembly including the toe-piece  2  and the heel-piece  3 , with respect to the gliding apparatus. 
     In the embodiment of the device illustrated in the drawing figures, by way of example, the first adjustment mechanism  6  makes it possible to adjust the position of the heel-piece  3 , and the second adjustment mechanism  7  makes it possible to adjust the position of the sub-assembly comprising the toe-piece  2  and the heel-piece  3 . 
     As shown in the particular embodiment illustrated in  FIG. 2   c , the first  6  and second  7  adjustment mechanisms are formed by longitudinal screws  6 . 1 ,  7 . 1 , respectively associated with the heel-piece  3 , on the one hand, and with the assembly formed by the toe-piece  2  and the heel-piece  3 , on the other hand. These longitudinal screws  6 . 1 ,  7 . 1  cooperate with corresponding racks  6 . 2 ,  7 . 2  connected to the base  1 . In general, the structure and the working principle of this type of mechanism for adjusting the longitudinal position of a retaining element is known to one of ordinary skill in the art, for example from the document FR 2 831 455 and U.S. Pat. No. 4,522,422, the disclosures of which are hereby incorporated by reference thereto in their entireties. Furthermore, it is clear to the skilled person that any other adjustment structure equivalent to these adjustment structures, such as a rack cooperating with corresponding levers located on the toe-piece and/or the heel-piece, one or more rods provided with projections, or other similar structures, may replace the adjustment structures illustrated in the various drawing figures. 
     To achieve the objectives described herein, the device for binding articles of footwear on a sliding apparatus according to the present invention more particularly comprises a structure  8  for indicating a reference point  9  located between the toe-piece  2  and the heel-piece  3 . The indication of the reference point  9  occurs automatically in all states of the binding device, including when adjusting the binding device. The invention provides the user of the ski binding with information related to a reference point to be aligned or positioned with respect to a reference mark normally present on the ski. Such a reference mark may be the actual center of the ski, a mark on the ski indicating the position intended for the boot center in order to obtain desired gliding characteristics, or any other type of indication on the ski. 
     Advantageously, and as described hereinafter, the indication structure  8  is a strictly mechanical structure, not incorporating any electronic components. By being strictly mechanical, the indication structure  8  is simple, economical, and strong. 
     To this end, the reference point  9  indicated by the indication structure  8  designates, in general terms, a predefined ratio between the distance between a front reference frame  2 . 1 , or plane, associated with the toe-piece  2  and the reference point  9 , on the one hand, and the distance between the reference point  9  and a rear reference frame  3 . 1 , or plane, associated with the heel-piece  3 , on the other hand, regardless of the spacing between the toe-piece  2  and the heel-piece  3 . Advantageously, the reference point  9  designates the boot center, referred to as the “MC”, that is to say, the aforementioned predefined ratio is 1:1. The boot-center position is commonly used as a reference for adjusting a binding in relation to a ski. However, other ratios or references can be targeted. 
     Furthermore, to simplify the understanding in the following description, reference will be made interchangeably to a front reference plane  2 . 1  associated with the toe-piece  2  or to a toe-piece  2 , and interchangeably to a rear reference plane  3 . 1  associated with the heel-piece  3  or to a heel-piece  3 . These reference planes each define a longitudinal position of an element of the boot binding device with respect to the gliding apparatus on which the device is attached, along the longitudinal plane  1 . 1 .  FIG. 4   c  illustrates these reference planes  2 . 1 ,  2 . 3 . The front reference plane  2 . 1  associated with the toe-piece  2  corresponds, e.g., to a plane perpendicular to the longitudinal  1 . 1  and passing through the contact surface, along the longitudinal plane  1 . 1 , between the front  10 . 3  of the sole and the toe-piece  2 . Generally speaking, the sole  10 . 1  presses longitudinally on a sliding plate of the toe-piece  2 , this plate defining the front reference plane  2 . 1 . The rear reference plane  3 . 1  associated with the heel-piece  3  corresponds, e.g., to a plane perpendicular to the longitudinal plane  1 . 1  and passing through the contact points, along the longitudinal plane  1 . 1 , between the rear  10 . 4  of the sole and the heel-piece  3 . Generally speaking, the sole  10 . 1  presses longitudinally on a top of the edge of the heel-piece  3 . In this case, the distance between the front reference plane  2 . 1  associated with the toe-piece  2  and the rear reference plane  3 . 1  associated with the heel-piece  3  corresponds directly to the length of the sole  10 . 1 , that is to say, to the size of the boot  10  as defined by the current standard. It is also possible to select other reference planes. 
     As shown more particularly in  FIGS. 2   a  and  2   c , the indication structure  8  includes a first indicating element  8 . 1  attached to the toe-piece  2  and a second indicating element  8 . 2  attached to the heel-piece  3 . In exemplary illustrated embodiments, the first  8 . 1  and second  8 . 2  indicating elements are formed by two superposed members, such as rigid blades or plates, housed in a longitudinal guide groove formed in the base  1  of the ski binding. Alternatively, the first  8 . 1  and second  8 . 2  indicating elements are formed by other equivalent structures, such as rods, straps, or bands, for example. 
     According to the first embodiment shown in  FIGS. 1 to 3   c , the first  8 . 1  and second  8 . 2  indicating elements are arranged so as to define, in all of the relative positions between the toe-piece  2  and heel-piece  3  that can be defined using the adjustment structures  6 ,  7 , an isosceles triangle  8 . 3  of variable size, one vertex of which indicates the reference point  9 . This is particularly shown in  FIGS. 1 and 2   a . Indeed, each of the first  8 . 1  and second  8 . 2  indicating elements defines a line  8 . 1 . 1 ,  8 . 2 . 1 , respectively, inclined at an identical angle α in relation to the longitudinal axis  1 . 1  of the gliding apparatus, as shown in  FIG. 3   a . These lines  8 . 1 . 1  and  8 . 2 . 1  are symmetrical in relation to an axis perpendicular to the longitudinal axis  1 . 1 . The angle α is determined for a particular binding device. The value of the angle is within an angular range of 15° to 75° or, in a particular range of embodiments, within an angular range of 30° to 60°. 
     It is possible to make these lines  8 . 1 . 1  and  8 . 2 . 1  of the first  8 . 1  and second  8 . 2  indicating elements in different ways. For example, as illustrated in  FIGS. 1 to 3   c , the first  8 . 1  and second  8 . 2  indicating elements can be formed by two superposed blades, at least one of which is angled, or inclined. Alternatively, the two blades are angled, or inclined, so that the two inclined edges of the blades form a “V”, the intersection of which indicates the reference point  9 . The two blades may be of different colors. Alternatively, the first  8 . 1  and second  8 . 2  indicating elements are formed by superimposed blades, at least one of which has a pattern adapted to define the isosceles triangle  8 . 3  of variable size. For example, the lower blade  8 . 1  can have a pattern formed of two given colors so as to form the line  8 . 1 . 1 , whereas the upper blade  8 . 2  is transparent on one portion and opaque on another portion, the interface between these two portions forming the line  8 . 2 . 1 . In the illustrated embodiment, the lines  8 . 1 . 1  and  8 . 2 . 1  are defined by a lower blade  8 . 1  having a pattern and an inclined upper blade  8 . 2 . Other alternatives are also within the scope of the invention. For example, in the case in which the first  8 . 1  and second  8 . 2  indicating elements are formed by rods, the inclined lines  8 . 1 . 1 ,  8 . 2 . 1  can be defined by inclined striations, inclined grooves, inclined linear projections, or pins or needles of a type attached to the rods at an angle. 
     In an exemplary illustrated embodiment, at least one of the first  8 . 1  and second  8 . 2  indicating elements has a graduation  8 . 2 . 2 , or scale, adapted to simplify the reading of the reference point  9  indicated by the indication structure  8 . In the example shown particularly with reference to  FIGS. 1 and 2   a , the second indicating element  8 . 2 , formed by an inclined blade, includes for this purpose striations that are perpendicular to the longitudinal axis  1 . 1  of the ski, and of the base  1 , respectively. These striations are parallel and equidistantly separated. These striations form a graduation  8 . 2 . 2 , or scale, as described above. These striations make it possible to relate, intuitively and legibly, the reference point  9  indicated by the vertex of the isosceles triangle  8 . 3  with a reference mark indicating the ski boot-center. Indeed, depending upon the spacing between the retaining devices, the vertex of the isosceles triangle  8 . 3 , of variable size, merges with a singular point of the line  8 . 2 . 1 . This singular point is easily identifiable as it is positioned on a predetermined striation, or between two identified striations of the graduation  8 . 2 . 2 . 
     In addition, as is also apparent in  FIGS. 1 and 2   a , the base  1  includes a scale  1 . 2  adapted to describe the positioning of the reference point  9  indicated by the indication structure  8  with respect to the base  1 . Moreover, the scale  1 . 2  also makes it possible to describe the positioning of the base in relation to the gliding apparatus. The scale  1 . 2  includes the indication MC to designate the boot-center, for example. Furthermore, when the base  1  is mounted on the gliding apparatus, this indication should normally coincide with a corresponding reference mark on the ski, this reference mark indicating the ski boot-center. Furthermore, when the binding device is normally adjusted, this indication should be transversely aligned with the reference point  9 . If these two conditions are met, the adjustment of the binding is optimum for normal (standard) skiing conditions. The scale  1 . 2  includes a graduation extending on both sides of the indication MC and indicating the forward or rearward distance from the binding boot center. Alternatively, the graduation can extend only on one side of the indication MC, either forward of the ski or rearward of the ski. Alternatively, it is possible that the scale  1 . 2  describes the positioning of the reference point  9  in relation to the base  1  and in relation to the gliding apparatus, respectively, directly on the gliding apparatus instead of it being positioned on the base  1 . In view of the various gliding apparatuses, in particular their various widths that could affect the visibility of the scale  1 . 2  positioned on the gliding apparatus, positioning the scale on the base  1  can nevertheless be more practical. 
     In this way, advantageously, the user can easily, quickly, and accurately determine the relative positioning between the binding boot-center as currently adjusted on the ski binding and the ski boot-center, by reading the reference point  9  indicated by the vertex of the isosceles triangle  8 . 3  and by relating it, using the graduation  8 . 2 . 2  located on the second indicating element  8 . 2 , with the scale  1 . 2  located on the base  1 . This indication structure  8  facilitates the adjustment of the desired position of the binding boot-center in relation to the gliding apparatus and increases the accuracy of this operation. Due to this characteristic, it would be possible to perform a desired adjustment before even mounting the ski binding on the gliding apparatus, provided that the base is correctly positioned in relation to the ski during the subsequent assembly of the ski binding. In practice, the base is first attached to the ski, and then the toe-piece and heel-piece are attached to the base. Therefore, the adjustment often occurs after the binding has been mounted to the gliding apparatus. 
     In particular embodiments, at least one of the first  8 . 1  and second  8 . 2  indicating elements has a size scale  8 . 1 . 2  indicating the size of the boot selected depending upon the relative spacing between the toe-piece  2  and the heel-piece  3 . In the example shown, the lower blade  8 . 1  includes this size scale  8 . 1 . 2  indicating the boot sizes. The end of the upper blade then acts as a pointer on the size scale  8 . 1 . 2  by showing the value of the normalized length of the sole corresponding to the adjusted size. Thus, the end of the upper blade  8 . 2  and the size scale  8 . 1 . 2  form an arrangement to provide information about the relative spacing between the toe-piece  2  and the heel-piece  3 . This information arrangement is separate from the indication structure  8  described above. 
     In this way, when adjusting the ski binding, the user also has specific information regarding the boot size corresponding to the currently adjusted spacing between the toe-piece  2  and the heel-piece  3 . This characteristic also makes it possible to carry out the adjustment without requiring a boot of the right size. 
     In the example illustrated in  FIGS. 1 and 2   a , the currently adjusted spacing between the toe-piece  2  and the heel-piece  3  corresponds to a boot size in which the sole has a normalized length of 305 millimeters, as indicated by the size scale  8 . 1 . 2  in cooperation with the visible end of the upper blade  8 . 2  forming the second indicating element  8 . 2 . This spacing can be modified using the first adjustment structure  6  for adjusting the position of the heel-piece  3 , by turning the corresponding longitudinal screw  6 . 1 . 
     Furthermore, the position of the binding boot-center, indicated by the reference point  9  of the indication structure  8  is adjusted in this case such that it coincides with a reference mark on the ski indicating the ski boot-center. Hypothetically, the base  1  is fixed to the ski so that the indication MC of the scale  1 . 2  of the base  1  coincides with the reference mark indicating the ski boot-center. The second adjustment structure  7  makes it possible to adjust the position of the sub-assembly comprising the toe-piece  2  and the heel-piece  3  in relation to the base  1 , and therefore to modify the relative positioning between the binding boot-center and the ski boot-center. 
     In certain embodiments, the binding device comprises a base  1 , first and second portions movable longitudinally in relation to the base  1 . The first portion includes the heel-piece  3 , the upper blade  8 . 2 , and the longitudinal screw  6 . 1  of the first adjustment structure  6 . These elements are longitudinally integrated. The second portion includes the toe-piece  2 , the lower blade  8 . 1 , the rack  6 . 2  of the first adjustment structure  6  and the longitudinal screw  7 . 1  of the second adjustment structure  7 . These elements are longitudinally integrated. The rack  6 . 2  is either formed directly in the lower blade  8 . 1 , or it is attached to the lower blade  8 . 1 . Thus, the first and second portions are connected to one another via the first adjustment structure  6 , thereby forming a sub-assembly movable longitudinally with respect to the base  1 . The adjustment of the longitudinal position of the subassembly is carried out via the second adjustment structure  7 , the longitudinal screw  7 . 1  cooperating with a rack  7 . 2  connected to the base  1 . Thus, an adjustment of the position of the toe-piece  2 , made by turning the corresponding longitudinal screw  7 . 1 , simultaneously causes a longitudinal movement of the same distance and direction of the heel-piece  3 , so that the relative positioning between the toe-piece  2  and the heel-piece  3  is not modified by this adjustment. 
     Consequently, the user can adjust the position of the heel-piece  3  in relation to the toe-piece  2 , as well as the position of the subassembly comprising the toe-piece  2  and heel-piece  3  in relation to the base  1 . Therefore, the first adjustment structure  6  makes it possible to vary the size of the boot by moving the toe-piece  2  and heel-piece  3  apart from or closer to one another, whereas the second adjustment structure  7  makes it possible to vary the binding boot-center in relation to the ski boot-center by adjusting the longitudinal position of the subassembly comprising the toe-piece  2  and the heel-piece  3 . 
       FIGS. 3   a ,  3   b , and  3   c  show examples of relative positionings that are quickly and easily achievable by the user having a ski binding according to the present invention, by using the first  6  and second  7  adjustment structures, as well as the indication structure  8 . 
       FIG. 3   a  shows a top view of the device, similar to  FIG. 2   a , the spacing between the toe-piece and heel-piece still being adjusted so as to correspond to a boot size, in which the sole has a normalized length of 305 millimeters. In this case, the binding boot-center as indicated by the reference point  9  has been adjusted, using the second adjustment structure  7 , so as to be positioned forward, that is to say, toward the toe-piece  2 , and, in this case, by a forward distance of 25 mm in relation to the ski boot-center. 
       FIG. 3   b  is another top view of the device, similar to  FIG. 2   a , the spacing between the toe-piece and the heel-piece still being adjusted so as to correspond to a boot size of 305 millimeters. In this case, the binding boot-center as indicated by the reference point  9  has been adjusted, using the second adjustment structure  7 , so as to be positioned rearward, that is to say, toward the heel-piece  3 , and, in this case, by a rearward distance of 25 mm in relation to the ski boot-center. 
       FIG. 3   c  is another top view of the device, similar to  FIG. 2   a , the spacing between the toe-piece and heel-piece having been adjusted in this case, using the first adjustment structure  6 , so as to correspond to a boot size, in which the sole has a normalized length of 325 millimeters. The binding boot-center, as adjusted on the binding, coincides here again with the ski boot-center. 
     In addition to the foregoing, other embodiments of the device are within the scope of the invention. 
     For example, the first  6  and second  7  adjustment structures are arranged differently. These structures  6 ,  7  can simply be reversed. In this alternative embodiment, the first adjusting structure  6  is assigned to the toe-piece and makes it possible to adjust the position of the toe-piece  2 , that is to say, the relative position between the toe-piece  2  and the heelpiece  3 , and the second adjustment structure  7  is assigned to the heel-piece  3  and makes is possible to adjust the position of a sub-assembly comprising the toe-piece  2  and the heel-piece  3 , that is to say, the binding boot-center relative to the ski boot-center. In view of the above explanations, it is clear that, to obtain this configuration, it is sufficient to extend the blade  8 . 2  attached to the heel-piece  3 , which, in this case, would become the bottom blade, and to position the toe-piece  2 , including the first adjustment structure  6 , on this extended blade  8 . 2 . 
     In another alternative embodiment of the device, the first adjustment structure  6  makes it possible to adjust the position of the one toe-piece  2  and heel-piece  3 , and the second adjustment structure  7  makes it possible to adjust the position of the other heel-piece  3  and toe-piece  2 . Although this embodiment still makes it possible to achieve the advantages described above, the adjustment will take longer because it requires iteration of the adjustment using the first  6  and second  7  adjustment structures. Compared to the prior art, however, it still enables a more intuitive and precise adjustment, given that all the necessary information for the adjustment are visually indicated by the device. 
     Advantageously, the indication structure  8  makes it possible to define a reference point  9  corresponding to any ratio, and not necessarily the ratio 1:1. For example, as shown in  FIG. 5 , the indication structure  8  forms a triangle, the inclined lines  8 . 1 . 1  and  8 . 2 . 1  of which are oriented at angles α 1  and α 2 , respectively, in relation to the longitudinal axis  1 . 1 . These angles α 1  and α 2  are selected so that the indication structure  8  makes it possible to define a predefined ratio between the distance x 1  between the front reference frame  2 . 1  associated with the toe-piece  2  and the reference point  9 , on the one hand, and the distance x 2  between the reference point  9  and the rear reference frame  3 . 1  associated with the heel-piece  3 , on the other hand. In this case, the reference point  9  does not necessarily designate the boot-center, but still designates the same predefined ratio, regardless of the spacing between the toe-piece  2  and the heel-piece  3 . Starting from the equation x 1 ′/x 2 ′=x 1 /x 2 , where x 1 ′ corresponds to the longitudinal distance between the reference point  9  and the vertex of the triangle formed by the indication structure  8  located on the side of the toe-piece  2 , and where x 2 ′ corresponds to the longitudinal distance between the reference point  9  and the vertex of the triangle formed by the indication structure  8  located on the side of the heel-piece  3 , and given the fact that the sum of x 1  and x 2  corresponds to the length of the sole  10 . 1 , the diagram of  FIG. 5  makes it possible to deduce the following relationship: 
       tan(π/2−α 1 )= x   1   /x   2  tan(π/2−α 2 ),
 
     which then makes it possible to calculate the angles α 1 , α 2  of the inclined lines  8 . 1 . 1 ,  8 . 2 . 1 , respectively, of a triangle constituting an indication structure  8  for a predefined ratio of x 1 :x 2 . One could want to position the reference point  9  beneath a metatarsophalangeal zone, for example. 
     Thus, the embodiment shown in  FIGS. 1 to 4   c  is a particular ratio of this solution for which α 1 =α 2  and x 1 =x 2 . This ratio makes it possible to obtain the isosceles triangle described above. 
     Alternatively, the indication structure  8  can even be formed by other suitable geometric shapes, and not just a triangle. For example, the indication structure  8  can be formed by a rhombus, meaning that instead of being inlined, one of the corresponding blades may include a notch in the shape of a recumbent “V”, and the complementary pattern on the other one of the blades also forms a complementary recumbent “V” to produce the rhombus. Indeed, what is important, in generalizing the criterion applicable to the indication structure  8 , is that the indication structure  8  comprises a first indicating element  8 . 1 , associated with the toe-piece  2 , and a second indicating element  8 . 2 , associated with the heel-piece  3 , so that the first  8 . 1  and second  8 . 2  indicating elements are arranged to define, in all of the relative positions between the toe-piece  2  and the heel-piece  3 , a geometric  figure 8.3 , a singular point of which indicates the reference point  9 . It is therefore clear to one of ordinary skill in the art, having the technical instruction according to the present description, that all of the suitable geometric shapes can be considered. An isosceles triangle, a triangle with sides forming the angles α 1 , α 2  relative to the longitudinal axis of the device, or a rhombus, the singular point of which is in each case one of the vertices of the geometric figure, form only a few examples of a suitable geometric  figure 8.3 . 
     Finally, the present invention also relates to any gliding apparatus including a boot binding device as described above, which, in particular, may be an alpine ski or a touring ski. 
     In light of the above explanations related to the structure and operation of the device according to the present invention, such a device has a number of advantages and makes it possible to achieve the goals outlined above. In particular, a ski binding according to the present invention provides a simple, fast, and accurate adjustment of the binding boot-center in relation to the ski boot-center. In addition, this adjustment does not require inserting a boot in the binding. Similarly, the device provides a plurality of various but well-defined positions between the binding boot-center and the ski boot-center, so that the user can easily customize the position of the boot on the ski. For example, an experienced skier, when adjusting the binding to his/her boot size, can also customize its position in relation to the ski, if desired, by easily modifying the recommendations indicated on the ski with respect to the position of the boot-center, whereas a less confident skier can adjust the binding as recommended. Indeed, the ski binding not only has indication structures providing the necessary information automatically during the adjustment, but also has optimally adjusted adjustment structures to carry out the corresponding adjustments. Furthermore, these adjustment structures are structurally strong, simple, fast, and reliable during use. The ski binding according to the invention can be broken down into a plurality of variants and thus has a flexible construction principle. Due to the relatively simple structure of such a ski binding, these advantages are achieved without unduly increasing the complexity or the production cost of the device. It is easily understandable that the advantages are particularly favorable, for example for a quick adjustment by an experienced skier wishing to adapt his/her binding to the gliding conditions. 
     At least because the invention is disclosed herein in a manner that enables one to make and use it, by virtue of the disclosure of particular exemplary embodiments of the invention, the invention can be practiced in the absence of any additional element or additional structure that is not specifically disclosed herein.