Abstract:
Since a large part of an outer tube is made of light alloy such as aluminum, plating on a surface of the outer tube sometimes peels off. Thus, the surface of the outer tube is generally painted. However, a problem is presented in the external appearance of the outer tube due to painting. A structure of a front fork includes an outer tube into which an inner tube is movably inserted in an axial direction thereof. A stepped part is formed in the outer tube with a third elastic member fitted to the stepped part. A tube cover includes a lower portion which is supported by the third elastic member. Since an outer surface of the tube cover covering the outer tube is plated, the external appearance can be enhanced. Even if the outer tube has a rough surface, light metal castings or forgings can be used.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present non-provisional application claims priority under 35 USC 119 to Japanese Patent Application No. 2003-193811 filed on Jul. 8, 2003 the entire contents thereof is hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an improvement in a structure of a front fork. 
   2. Description of Background Art 
   Techniques are known for improving the structure of a front fork. See, for example, Japanese Patent Laid-Open Publication No. Hei 11 (1999)-51106 ( FIG. 4 ). 
     FIG. 22  is a view of  FIG. 4  of Japanese Patent Laid-Open Publication No. Hei 11 (1999)-51106. Note that the reference numerals have been redesignated. 
   A dust cover  160  includes, as the main components a stopper  161  fixed on an outer peripheral surface of an inner tube  113 , a cover sheet  162  is fitted on the stopper  161  and the dust cover  160  is fitted to the inner tube  113  with the cover sheet  162  interposed therebetween. 
   The dust cover  160  covers a lower part of the inner tube  113  of a front fork  110 . Thus, the dust cover  160  serves as a mudguard. 
   For example, in a motorcycle, the front fork  110  is a member that includes highly visible exterior components. Thus, it is best for the front fork  110 , as the exterior component, to have a pleasing appearance. 
   Plating is one technique for improving the exterior appearance of the front fork  110 . It is preferable to plate the outer tube  112  of the front fork  110  and the outer peripheral surface of the dust cover  160 . 
   Moreover, the outer peripheral surface of the inner tube  113  is similarly plated. Thus, slidability with respect to the outer tube  112  as well as the exterior appearance can be improved. 
   In addition, in general, a steel pipe is used for the inner tube  113  and a steel pipe or a steel tube is used for the dust cover  160 . Meanwhile, for the outer tube  112 , a light alloy casting such as an aluminum casting is used in order to achieve a certain appearance and to achieve a weight reduction with respect to the outer tube  112 . 
   When the inner tube  113  and the dust cover  160 , which are made of steel, are plated, the adhesion strength of the plating is sufficiently increased. 
   However, when the outer tube  112 , which is manufactured by use of a light alloy casting, is plated, it is discovered that the following problems occur. 
   The hardness of an aluminum alloy casting (JIS H 5202 AC4C-T61) is about HB (10/500) 90. Meanwhile, the hardness of the Cr plating is HB 450 or more. There is a significant difference in hardness between the aluminum alloy casting, that is the base material, and a plated layer, that is the coating. 
   Accordingly, when a load is applied to the front fork and the front fork is bent, cracks may be caused in the plating due to the difference in hardness. Thus, when the outer tube, which is made of a light alloy, is plated, it is required to increase the rigidity of the outer tube by use of means for increasing the wall thickness of the outer tube or the like and to form the outer tube to have a shape not to be bent. Consequently, an increase in weight and cost are incurred. 
   Accordingly, as the second best solution, the adopted of a method of painting the surface of the outer tube is proposed. However, if the outer tube is painted and the inner tube and a duct cover are plated, there is a difference between the appearance of painting and appearance of the plating. Thus, there remains a problem such as a lack of visual uniformity. 
   SUMMARY AND OBJECTS OF THE INVENTION 
   Consequently, an object of the present invention is to provide a technology capable of entirely plating the front fork including the outer tube. 
   In order to achieve the foregoing object, according to the present invention, a pair of inner tubes are inserted into a pair of left and right outer tubes movably in an axial direction thereof. In addition, in a front fork supporting a front wheel, the outer tube is covered with a tube cover and an outer surface of this tube cover is plated. 
   Since the outer surface of the tube cover which covers the outer tube is plated, the external appearance can be enhanced. As a result, the tube cover, which covers the outer tube, and the inner tube can be plated. Thus, the whole external appearance of the front fork can be integrated. 
   Moreover, since the outer tube is covered with the tube cover, light metal castings or forgings can be used even if the outer tube has a rough surface. 
   According to the present invention, the tube cover is attached to the front fork side with an elastic member interposed therebetween. 
   Since the tube cover is fixed by means of the elastic member, the tube cover is not bent as much as the front fork. 
   As a result, it is possible to prevent the occurrence of cracks and peeling due to bending of a plated layer formed in the tube cover. 
   According to the present invention, at least one of both ends of the tube cover is attached to a stepped part which the outer tube is provided with. 
   In attaching the tube cover, the attachment is performed by pressing a part of the tube cover against the stepped part formed in the outer tube. 
   Therefore, in attaching the tube cover, it is easy to position the tube cover. Thus, assembling efficiency of the outer tube and the tube cover can be improved. 
   According to the present invention, a convex-concave part is formed on an inner peripheral surface of the elastic member. In addition, convex portions are brought into contact with the front fork side. 
   On the inner peripheral surface of the elastic member, a spline-shaped convex-concave part is formed. In addition, only the convex portions are brought into contact with the front fork side. 
   Since only the convex portions on the inner peripheral surface are brought into contact with the front fork side, it is possible to reduce the force required to fit the elastic member into the outer tube. Thus, assembling efficiency can be improved. 
   Furthermore, it is possible to easily discharge rain water entering between the tube cover and the front fork through the concave portions formed on the inner peripheral surface. 
   According to the present invention, the front fork is an inverted front fork in which the inner tubes are inserted from below the outer tubes. In addition, a top bridge or a bottom bridge of the inverted front fork fixes one end of the tube cover. 
   In the inverted front fork, the top bridge or the bottom bridge fixes the one end of the tube cover. 
   Since the top bridge or the bottom bridge directly fixes the tube cover, it is not required to provide an additional member for fixing the tube cover. Thus, a reduction in the number of items and a reduction in the weight can be achieved. 
   Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
       FIG. 1  is a side view of a motorcycle according to the present invention; 
       FIG. 2  is an exploded perspective view of a structure of a front fork according to the present invention; 
       FIG. 3  is a front view of a main part of the structure of the front fork according to the present invention; 
       FIG. 4  is a cross-sectional view taken along the line  4 — 4  of  FIG. 3 ; 
       FIG. 5  is a perspective view of a third elastic member according to the present invention; 
       FIG. 6  is a cross-sectional view taken along the line  6 — 6  of  FIG. 5 ; 
       FIG. 7  is a perspective view of a second elastic member according to the present invention; 
       FIG. 8  is a cross-sectional view taken along the line  8 — 8  of  FIG. 7 ; 
       FIG. 9  is a perspective view of an upper tube cover according to the present invention; 
       FIG. 10  is an enlarged view of an area  10  of  FIG. 3 ; 
       FIG. 11  is a perspective view of a front turn signal bracket according to the present invention; 
       FIG. 12  is a perspective view of a rear turn signal bracket according to the present invention; 
       FIG. 13  is a perspective view of a first elastic member according to the present invention; 
       FIG. 14  is a view from a direction of the arrow  14  of  FIG. 13 ; 
       FIG. 15  is an explanatory view showing an assembly method for the third elastic member; 
       FIG. 16  is an explanatory view showing an assembly method for a tube cover; 
       FIG. 17  is an explanatory view showing an assembly method for a bottom bridge and turn signal brackets; 
       FIG. 18  is an explanatory view showing an assembly method for the bottom bridge and a head pipe; 
       FIG. 19  is an explanatory view showing an assembly method for the upper tube cover and a top bridge; 
       FIG. 20  is an explanatory view when assembly of the tube cover and the upper tube cover is completed; 
       FIG. 21  is a view showing another embodiment of  FIG. 3 ; and 
       FIG. 22  is a view redisplaying patent document 1. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Based on the accompanying drawings, an embodiment of the present invention will be described below.  FIG. 1  is a side view of a motorcycle according to the present invention. The motorcycle  10  includes a main frame  11  with a front fork  13  that is attached by means of a head pipe  12  so as to be steerable. The head pipe  12  is formed in a front portion of the main frame  11 . A front wheel  14  is attached to a lower portion of the left and right front fork  13 . An engine  15  is mounted on the main frame  11  with an exhaust pipe  17  through which exhaust gas discharged from the engine  15  flow to a muffler  16 . A fuel tank  18  and a passenger seat  19  are disposed in front and rear portions of the main frame  11  with a swing arm  22  attached in the rear portion of the main frame  11  so as to be movable up and down by means of a rear shock absorber  21 . A rear wheel  23  is attached to a rear portion of the swing arm  22 . 
   The left and right front fork  13  includes turn signals  24  attached so as to protrude left and right from the front fork  13 . Inner tube covers  27  are attached to the left and right sides so as to cover the inner tubes  26  by means of cover brackets  25 . A headlight  28  is provided together with a mirror  29 . 
     FIG. 2  is an exploded perspective view of a structure of the front fork according to the present invention.  FIG. 2  shows that the structure of the front fork is assembled in the following manner. Specifically, the inner tubes  26  are inserted into outer tubes  31  and are movably in an axial direction thereof. Tube covers  32  are put on the outer tubes  31  and a bottom bridge  34  is placed on the tube covers  32 . Turn signal brackets  35  are attached on the bottom bridge  34  and a top bridge  36  is placed thereon, the top bridge  36  having upper tube covers  33  fixed thereto. 
   The head pipe  12  formed in the front portion of the main frame and is put through a stem shaft  37  placed so as to extend upwardly in a vertical direction on the bottom bridge  34 . Accordingly, the head pipe  12  is sandwiched by the top bridge  36  and the bottom bridge  34 . 
   More specifically, the front fork  13  is fixed by the top bridge  36  and the bottom bridge  34 . In addition, the stem shaft  37  is provided on the bottom bridge  34  and is attached so as to be steerable by the head pipe  12  formed in the front portion of the main frame  11 . Thus, the front fork  13  can be moved around the stem shaft  37 . 
   A lower holder  38  is placed on an upper surface of the top bridge  36  and a handle  41  is fixed by this lower holder  38  and an upper holder  39 . Thus, the direction of the front fork  13  can be operated by operating the handle  41 . 
   A front fender  42  is attached inside of the left and right front fork  13  and the inner tube covers  27  are attached to both of the outsides of the left and right front fork  13  with the cover brackets  25  interposed therebetween. 
   Front wheel fixing members  20   a  to  20   d  are provided relative to the front wheel  14 . 
     FIG. 3  is a front view of a main part of the structure of the front fork according to the present invention. The front fork  13  includes the inner tubes  26  inserted into the outer tubes  31  movably in the axial direction thereof. The tube covers  32  cover the outer tubes  31  and have their outer surfaces plated. The bottom bridge  34  is disposed on the tube covers  32 . 
   A lower portion of each of the tube covers  32  is fixed to the outer tube  31  by means of a third elastic member  43 . 
   The front fork uses a structure in which the lower portion of the tube cover  32  is attached to a stepped part  44  provided with the outer tube  31 . However, there is no harm in changing a position of the stepped part  44  to which the outer tube  31  is provided with, as the need arises, and arbitrarily setting the position of the stepped part  44  such as attaching an upper portion of the tube cover  32 , for example. 
   Note that a second elastic member  46  is fitted to an upper end portion  45  of the tube cover  32 . 
   Meanwhile, an upper part of the front fork  13  includes the turn signal brackets  35  which are disposed on the bottom bridge  34  and fixed around the outer tubes  31 . The upper tube covers  33  are attached on the turn signal brackets  35  and the top bridge  36  includes the upper tube covers  33  fixed thereto. 
   The upper tube covers  33  are attached to the top bridge  36  by means of fixed brackets  47  and bolts  48 . In addition, a first elastic member  49  is fitted to a lower end portion of each of the upper tube covers  33 . 
   Similar to the tube cover  32 , the upper tube cover  33  is a member which covers the outer tube  31  and includes an outer surface that is plated. 
     FIG. 4  is a cross-sectional view taken along the line  4 — 4  of  FIG. 3 .  FIG. 4  shows the outer tube  31  into which the inner tube  26  is movably inserted in the axial direction thereof. The stepped part  44  is formed in the outer tube  31  with the third elastic member  43  fitted to the stepped part  44  and the tube cover  32  of which lower portion is supported by the third elastic member  43 . A surface of the tube cover  32  is subjected to a chrome plating processing. 
   A bushing  51  is provided together with a back up ring  52 , a stopper ring  53  and a dust seal  54 . 
   At least one of both ends of the tube cover  32  is attached to the stepped part  44  formed in the outer tube  31 . Thus, in attaching the tube cover  32 , the positioning of the tube cover  32  is facilitated. 
   As a result, the assembling efficiency of the outer tube  31  and the tube cover  32  can be improved. 
   Moreover, since the tube cover  32  is fixed by means of the third elastic member  43 , the tube cover  32  is not bent as much as the outer tube  31 . 
   As a result, it is possible to prevent the occurrence of cracks and peeling due to bending of a plated layer formed on the surface of the tube cover  32 . 
     FIG. 5  is a perspective view of the third elastic member according to the present invention. The third elastic member  43  includes convex portions  56  that are formed on an inner peripheral surface  55  having a convex-concave part formed thereon. The concave portions  57  of a convex-concave part are formed on a lower surface orthogonal to the inner peripheral surface  55 . 
   With reference to  FIG. 4 , the concave portions are formed on the inner peripheral surface and lower surface of the third elastic member  43 . Thus, it is possible to discharge water and the like entering between the outer tube  31  and tube cover  32  of the front fork to the outside through the concave portions  57  (see  FIG. 5 ). 
   In  FIG. 5 , a spline-shaped convex-concave part is formed on the inner peripheral surface  55  of the third elastic member  43 . In addition, convex portions  56  of the convex-concave part are brought into contact with the front fork side. 
   The convex portions  56  and the outer tube  31  are brought into contact with each other in fitting the third elastic member  43  to the outer tube  31  (see  FIG. 4 ). Accordingly, a contact area between the third elastic member  43  and the outer tube  31  is reduced. Thus, fitting of the third elastic member  43  can be facilitated. As a result, the assembling efficiency of the outer tube  31  and the third elastic member  43  can be improved. 
   The material of the third elastic member  43  may be rubber or a plastic such as resin. There is no limitation on the kind of material as long as the material is one which satisfies a predetermined strength, elasticity, durability and the like that are required for supporting the tube cover  32  (see  FIG. 4 ). 
     FIG. 6  is a cross-sectional view taken along the line  6 — 6  of  FIG. 5 .  FIG. 6  shows that a metal member  58  is sealed in the ring-shaped third elastic member  43 . Since the metal member  58  is sealed in the ring-shaped inside thereof, the rigidity and durability of the third elastic member  43  can be significantly improved. 
     FIG. 7  is a perspective view of the second elastic member according to the present invention. In the second elastic member  46 , triangular grooves  62  are formed on an inner peripheral surface  61  of the second elastic member  46  and an upper end portion  63  thereof is additionally provided with a guard-shaped lip  64 . 
   Moreover, since the grooves  62  are formed on the inner peripheral surface  61  of the second elastic member  46 , the outer tube is brought into contact with top portions of these grooves  62  in fitting the second elastic member  46  to the outer tube  31  (see  FIG. 3 ). Accordingly, a contact area between the inner peripheral surface  61  and the second elastic member  46  is reduced. Thus, the fitting of the second elastic member  46  to the outer tube can be facilitated. 
   As a result, the assembling efficiency of the second elastic member  46  and the outer tube can be improved. 
   The material of the second elastic member  46  may be rubber or plastic such as resin. There is no limitation on the kind of material as long as the material is one which satisfies a sufficient strength, elasticity, durability and the like that are capable of fitting the second elastic member into the upper end portion of the tube cover  32  (see  FIG. 3 ) and holding the tube cover  32  around the outer tube. 
     FIG. 8  is a cross-sectional view taken along the line  8 — 8  of  FIG. 7 . The upper end portion  63  of the second elastic member  46  is additionally provided with the guard-shaped lip  64 . In addition, this lip  64  is disposed so as to be brought into contact with the bottom bridge  34  (see  FIG. 3 ). 
   The upper end portion  63  is additionally provided with the guard-shaped lip  64 . Thus, even if there is some variation in a length of the tube cover  32 , this variation is absorbed by the lip  64  in attaching the tube cover  32  to the outer tube  31 . Accordingly, a gap between the lip  64  and the bottom bridge  34  is sealed and a predetermined sealing effect is achieved. Thus, it is possible to prevent water from entering into the tube cover  32 . 
     FIG. 9  is a perspective view of the upper tube cover according to the present invention. The upper tube cover  33  includes the flange-shaped fixed bracket  47  having two holes therein in its upper end portion. The first elastic member  49  is fitted to a lower end portion  65  thereof. A surface of the upper tube cover  33  is subjected to a chrome plating processing. 
   The upper tube cover  33  can be fixed to a lower surface of the top bridge  36  (see  FIG. 3 ) by means of the fixed bracket  47 . 
     FIG. 10  is an enlarged view of the area  10  in  FIG. 3 .  FIG. 10  shows that the upper tube cover  33  fitted to the outer tube  31  is fitted into a groove portion  66  formed in the upper end portion  45  of the turn signal bracket  35  by means of the first elastic member  49 . 
   By providing spaces S and S between the first elastic member  49  and the upper end portion  45  of the turn signal bracket  35  and between the first elastic member  49  and a bottom  66   b  of the groove portion  66  of the turn signal bracket  35 , a variation in a length of the upper tube cover  33  can be absorbed. 
   Since the upper tube cover  33  is attached to the elastic member  49 , the upper tube cover  33  is not bent as much as the front fork. 
   As a result, it is possible to prevent the occurrence of cracks and peeling due to bending of a plated layer formed in the upper tube cover  33 . 
     FIG. 11  is a perspective view of a front turn signal bracket according to the present invention. The turn signal bracket  35  includes a front turn signal bracket  67  and a rear turn signal bracket. The front turn signal bracket  67  has a shape which is cut into halves in the axial direction of the outer tube. The turn signal  24  (see  FIG. 1 ) can be attached to an attachment surface  71  formed on a side  69  of the bracket  67 . 
   In order to fit the lower end portion of the upper tube cover  33  (see  FIG. 3 ), a groove portion  66  is formed to have a diameter D 2  and a depth D 1  from an upper end surface  72  of the turn signal bracket  67 . 
     FIG. 12  is a perspective view of the rear turn signal bracket according to the present invention. The rear turn signal bracket  68  has a shape which is cut into halves in the axial direction of the unillustrated outer tube. The rear turn signal bracket  68  can be attached to the outer tube  31  (see  FIG. 3 ) in combination with the front turn signal bracket  67  (see  FIG. 11 ). 
   As in the case of the front turn signal bracket  67  (see  FIG. 11 ), in order to fit the lower end portion of the upper tube cover  33  (see  FIG. 3 ), a groove portion  66  is formed in an upper end surface  72  of the rear turn signal bracket  68  to have a diameter D 2  and a depth D 1  from the upper end surface  72 . Furthermore, a notch  73  for discharging rain water accumulated in this groove portion  66  is formed. 
     FIG. 13  is a perspective view of the first elastic member according to the present invention.  FIG. 13  shows that the first elastic member  49  has convex portions  75  formed on its inner peripheral surface  74 . 
   Since the convex portions  75  are formed on the inner peripheral surface  74  of the first elastic member  49 , the convex portions  75  and the outer tube  31  (see  FIG. 10 ) are brought into contact with each other. Accordingly, in fitting the first elastic member  49  to the outer tube  31 , a contact area between the first elastic member  49  and the outer tube  31  is reduced. Thus, fitting of the first elastic member  49  to the outer tube  31  can be facilitated. 
   As a result, the assembling efficiency of the outer tube  31  and the first elastic member  49  can be improved. 
   The material of the first elastic member  49  may be rubber or a plastic such as resin. There is no limitation on the kind of material as long as the material is one which satisfies a predetermined strength, elasticity, durability and the like that are required for supporting the upper tube cover  33  (see  FIG. 3 ). 
     FIG. 14  is a view from a direction of the arrow  14  of  FIG. 13 .  FIG. 14  shows that the upper tube cover  33  (see  FIG. 9 ) can be fitted to the first elastic member  49 . 
   With reference to  FIG. 10 , since the convex portions  75  are formed on the inner peripheral surface of the first elastic member  49 , a space (concave portions) is formed between the inner peripheral surface of the first elastic member  49  and the outer tube  31 . Accordingly, even if water enters into the upper tube cover  33 , the water passes through this space and reaches the groove portion  66  of the turn signal bracket  35 . Thus, the water can be discharged to the outside from the notch  73  (see  FIG. 12 ) which is formed in a part of the groove portion  66 . 
   With reference to  FIGS. 15 to 20 , a method for assembling the front fork will be described below.  FIG. 15  is an explanatory view showing an assembly method for the third elastic member.  FIG. 15  shows that the third elastic member  43  is fitted to the outer tube  31  into which the inner tube  26  is inserted. 
   The spline-shaped convex-concave part is formed on the inner peripheral surface of the elastic member. Since only the convex portions are brought into contact with the front fork side, fitting can be facilitated. Thus, assembling efficiency can be improved. 
     FIG. 16  is an explanatory view showing an assembly method for the tube cover.  FIG. 16  shows that the tube cover  32  includes the second elastic member  46  fitted to its upper end portion that is put on the outer tube  31  having the third elastic member  43  fitted thereto. 
   In attaching the tube cover, a part of the tube cover  32  is pressed against the stepped part  44  formed in the outer tube  31 . Thus, the positioning of the tube cover  32  is facilitated. Accordingly, the assembling efficiency of the outer tube  31  and the tube cover  32  can be improved. In this event, it is preferable in terms of the operation that, in order to facilitate the operation of attaching the tube cover, soapy water is applied to an outer peripheral portion  77  on a side of the outer tube  31  and an outer peripheral portion of the third elastic member  43  before the attachment operation. 
     FIG. 17  is an explanatory view showing an assembly method for the bottom bridge and the turn signal brackets. The bottom bridge  34  is placed on the left and right front fork  13  which includes the outer tubes  31  having the tube covers  32  put thereon and the inner tubes  26 . The lower surface of the bottom bridge  34  is brought into contact with the lips  64  of the second elastic members  46  fitted to the upper end portions of the tube covers  32 . Furthermore, the turn signal brackets  35  including left and right front turn signal brackets and rear turn signal brackets are attached thereto. 
     FIG. 18  is an explanatory view showing an assembly method for the bottom bridge and the head pipe.  FIG. 18  shows that the front fork  13  can be attached to the main frame  11  by inserting the stem shaft  37  placed so as to extend upwardly on the bottom bridge  34  into the head pipe  12  fixed to the front portion of the main frame  11 . 
     FIG. 19  is an explanatory view showing an assembly method for the upper tube cover and the top bridge. The first elastic members  49  are previously fitted to the upper tube covers  33 . The top bridge  36  having the upper tube covers  33  fixed thereto by means of the fixed brackets  47  is fitted to the left and right front fork  13  from above. Thus, the top bridge can be fixed to the front fork by use of a stem nut  76 . 
     FIG. 20  is an explanatory view when the assembly of the tube covers and the upper tube covers is completed.  FIG. 20  shows that the outer tubes  31  can be covered with the tube covers  32  and the upper tube covers  33  by a series of operations of  FIGS. 15 to 19 . 
   The outer surfaces of the tube covers  32  covering the outer tubes  31  are plated. Thus, the external appearance can be enhanced. As a result, the tube covers  32  covering the outer tubes  31  and the inner tubes  26  can be plated. Consequently, the whole external appearance of the front fork  13  can be integrated. 
   Since the outer tubes  31  are covered with the tube covers  32  and the upper tube covers  33 , light metal castings or forgings can be adopted even if the outer tubes  31  have rough surfaces. 
   Both of the tube covers  32  and the upper tube covers  33 , which cover the outer tubes  31 , are fixed to the outer tubes  31  by means of a plurality of elastic members. Thus, there is no influence on rigidity of the front fork  13 . 
     FIG. 21  is a view showing another embodiment of  FIG. 3 .  FIG. 21  shows that, in an inverted front fork  13 , an elastic member  78  is fitted to an upper end of an upper tube cover  33  and the upper tube cover  33  is fixed to a top bridge  36 . 
   The upper tube cover  33  is fixed to the top bridge  36  by means of the elastic member  78 . Thus, it is not required to additionally provide a fixed bracket for fixing the upper tube cover  33 . 
   As a result, a reduction in the number of items and a weight reduction can be achieved. 
   Note that fixation of the upper tube cover  33  is performed by firmly fixing the upper tube cover  33  to the top bridge  36 . In addition, the fixation of the tube cover  32  is performed by adding a step to the outer tube  31  and putting the tube cover  32  on the outer tube  31 . However, the fixation of the upper tube cover  33  and the tube cover  32  is not limited to the combination described above but can be freely selected according to designed structures. For example, a method for firmly fixing the tube cover  32  to the bottom bridge  34  may be adopted. 
   Moreover, there is no harm in forming a plurality of holes such as small holes and slits in a part of the upper tube cover  33  and the tube cover  32 . 
   Furthermore, in the described embodiment, the surfaces of the upper tube cover  33  and the tube cover  32  are subjected to a hard chrome plating processing. However, other plating processes can be arbitrarily selected. 
   With the foregoing configuration, the present invention exerts the following effects. 
   According to the present invention, an outer tube of a front fork supporting a front wheel is covered with a tube cover and an outer surface of this tube cover is plated. Since the outer surface of the tube cover which covers the outer tube is plated, the external appearance can be enhanced. 
   As a result, the tube cover, which covers the outer tube, and an inner tube can be plated. Thus, the whole external appearance of the front fork can be integrated. 
   In addition, since the outer tube is covered with the tube cover, a light metal castings or forgings can be adopted even if the outer tube has a rough surface. 
   According to the present invention, the tube cover is attached to the front fork side with an elastic member interposed therebetween. Thus, it is possible to prevent the occurrence of cracks and peeling due to bending of a plated layer formed in the tube cover. 
   According the present invention, at least one of both ends of the tube cover is attached to a stepped part which the outer tube is provided with. Since one end of the tube cover is attached to the stepped part formed in the outer tube, in attaching the tube cover, positioning of the tube cover is facilitated. Thus, the assembling efficiency of the outer tube and the tube cover can be improved. 
   According to the present invention, a convex-concave part is formed on an inner peripheral surface of the elastic member. In addition, convex portions are brought into contact with the front fork side. Since the convex portions are formed on the inner peripheral surface, it is possible to reduce force required to fit the elastic member into the outer tube. 
   As a result, the assembling efficiency of the elastic member and the outer tube can be improved. 
   Furthermore, since concave portions are formed on the inner peripheral surface, it is possible to easily discharge rain water entering between the tube cover and the front fork through the concave portions. 
   According to the present invention, a top bridge or a bottom bridge of the inverted front fork fixes one end of the tube cover. Since the top bridge or the bottom bridge fixes the one end of the tube cover, it is not required to provide an additional member for fixing the tube cover. As a result, a reduction in the number of items and weight reduction can be achieved. 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.