Abstract:
The present invention is directed to a bicycle fork steerer tube of fibre composite material with a layer of metal circumferentially about the exterior of the fibre composite material. The layer of metal assists in wear resistance and increases strength.

Description:
[0001]    This application claims as under 35 U.S.C. 119 of U.S. Provisional Patent Application Ser. No. 61/136616 filed Sep. 19, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a bicycle fork steerer tube of a bicycle fork wherein the bicycle fork steerer tube includes non-metallic material, and more particularly to providing such a bicycle fork steerer tube to be plated with a metal or metal alloy as to advantageously change the properties of the non-metallic material, as for example to increase strength and wear resistance. 
       BACKGROUND OF THE INVENTION 
       [0003]    Bicycle racing is a highly competitive sport where riders are competing for the best possible times. Bicycles are being designed to assist the riders to achieve their best. One way to assist the rider is to design a bicycle that is as light as possible without losing the stiffness, strength or wear resistance. 
         [0004]    In the past, bicycle fork steerer tubes were made out of metal. Bicycle fork steerer tubes were originally typically made out of steel but as more emphasis was placed on reducing the weight of bicycles some bicycle fork steerer tubes were made out of aluminium. Metal bicycle fork steerer tubes are both strong and resilient but do not provide as lightweight a design as is desired for bicycle racing. 
         [0005]    To further reduce the weight of bicycles, some bicycle fork steerer tubes have been constructed out of non-metallic materials including notably carbon fibre and various fibres or combinations of fibres such as glass, Kevlar and carbon. These various fibres are placed in a polymer or other matrix to form the bicycle fork steerer tube structure. Such fibre composite bicycle fork steerer tubes can be lighter weight than traditional metal bicycle fork steerer tubes. 
         [0006]    While fibre composite bicycle fork steerer tubes are lighter, the fibre composite bicycle fork steerer tubes suffer the disadvantage that they do not have all of the beneficial properties of the metal tubes including the strength, rigidity or wear resistance. The reduction in strength and wear resistance can cause the fibre composite bicycle fork steerer tube to be damaged more easily than the metal bicycle fork steerer tubes. Furthermore, the fibre composite bicycle fork steerer tubes have the disadvantage that they are prone to failure if the surfaces of the tubes are damaged. These factors can disadvantageously affect the performance, reliability and length of service of the fibre composite bicycle fork steerer tubes. 
         [0007]    Bicycle fork steerer tubes are designed so that bicycle handlebars and other suitable devices can be clamped to the bicycle fork steerer tube. When the clamp is tightened around the bicycle fork steerer tube high loads are created on the steerer tube weakening the structure, such loads typically include point loads created at the location where the clamp is tightened potentially causing damage. 
         [0008]    While fibre composite materials can create strong structures, the strength depends on the direction of the fibres and they tend to be sensitive to point loads and impacts. 
         [0009]    A metal tube, on the other hand generally has essentially equal strength characteristics in all desired directions and higher tolerance for impact and point loads, but typically will weigh more than a fibre composite tube. 
       SUMMARY OF INVENTION 
       [0010]    To at least partially overcome these disadvantages of previously known devices, the present invention provides a bicycle fork steerer tube of composite materials where the exterior surfaces are plated with a metal or metal alloy. 
         [0011]    An object of the present invention is to provide a relatively lightweight bicycle fork steerer tube that exhibits the strength, rigidity and wear resistance of a metallic tube. 
         [0012]    The present invention is directed to a bicycle fork steerer tube made out of more than one material. In particular, the bicycle fork steerer tube is made of fibre composite material plated with a metal or metal alloy. The fibre composite material creates a light structure. The metallic or metal alloy coating on the outside of the structure which adds rigidity, and wear resistance and protects the fibres from damage, especially due to point loads and impacts. 
         [0013]    The composite fibre portion of the bicycle fork steerer tube may be made of carbon fibre composite. The metallic or metal alloy portion may preferably be metal plating, more preferably a nano-grain metal alloy; more preferably the metal plating may be nickel plating. The metal plating need not extend the full-length of a bicycle fork steerer tube but may be only be a portion of the bicycle fork steerer tube where adjusted strength characteristics are desired. 
         [0014]    Depending on the fork manufacturing technique the bicycle fork steerer tube may extend into the crown, in which case the plating may extend in the crown as well. The plating may also extend into the crown of the bike for ease of manufacturing. 
         [0015]    The metal plating may be either uniform over a surface of the bicycle fork steerer tube or may vary in composition and/or thickness. 
         [0016]    The present invention further provides a front fork of a bicycle having a bicycle fork steerer tube wherein the bicycle fork steerer tube comprises non-metallic material which is plated by a metal or metal alloy. 
         [0017]    In a further aspect, the present invention provides a bicycle fork having a cylindrical steerer tube, a crown and a pair of fork arms for mounting of a front wheel therebetween,
   the crown having the steerer tube extending upwardly therefrom to an upper distal end of the steerer tube,   the crown having the fork arms extending downwardly therefrom to lower distal ends of the forks,   the steerer tube adapted to extend through a bicycle frame to rotatably couple the fork to the bicycle frame,   characterized by:   the steerer tube having an inner tube of fibre composite material and   a layer of metal circumferentially about a section of the inner tube forming an exterior surface of the steerer tube over the section of the inner tube.   
 
         [0024]    In a still further aspect, the present invention provides a steerer tube having proximate the upper distal end an upper clamp portion adapted for engagement by a clamp mechanism of a bicycle handlebar and the steerer tube having proximate the crown a lower journal portion adapted and to extend through the bicycle frame and be journalled therein,
   the layer of metal circumferentially about at least one of the upper clamp portion and the lower journal portion.   
 
         [0026]    In a further aspect, the present invention provides in combination with the bicycle frame and a handlebar; 
         [0027]    the handlebar having a clamp mechanism for engagement circumferentially about the steerer tube; 
         [0028]    the steerer tube above the crown having a lower journal portion and an upper clamp portion; 
         [0029]    the steerer tube extending through a bicycle frame with the lower journal portion of the steerer tube journalled in the bicycle frame to rotatably couple the fork to the bicycle frame,
   the upper clamp portion extending upwardly past the bicycle frame;   the clamp mechanism removably securing the handlebars to the steerer tube against relative rotation and against removal by applying forces to the exterior surface of the steerer tube,   the layer of metal circumferentially about at least one of the upper clamp portion and the lower journal portion.   
 
         [0033]    The layer of metal can be circumferentially about one or both of the upper clamp portion and the lower journal portion. 
         [0034]    The layer of metal on the steerer tube preferably has a thickness between 0.001 inches and 0.04 inches, and more preferably between 0.001 inches and 0.01 inches. 
         [0035]    In a still further aspect, the present invention provides a inner tube having an internal surface and a second layer of metal circumferentially about a section of the internal surface of the inner tube. 
         [0036]    The second layer of metal on the steerer tube preferably has a thickness between 0.001 inches and 0.04 inches, and more preferably has a thickness between 0.001 inches and 0.01 inches. 
         [0037]    In a further aspect, the present invention provides a crown of fibre composite material and a layer of metal extending over the section of the crown forming an forming an exterior surface of the steerer tube over the section of the crown. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    Further aspects and advantages of the invention will become apparent upon reading the following description together with the company drawings in which: 
           [0039]      FIG. 1  is a side view of a bicycle; 
           [0040]      FIG. 2  is an exploded partial perspective view of the front fork and handlebar stem of the bicycle of  FIG. 1  showing its bicycle fork steerer tube; 
           [0041]      FIG. 3  is a schematic perspective view of a short length of the composite bicycle fork steerer tube shown in  FIG. 2  with a portion cut away; 
           [0042]      FIG. 4  is a schematic perspective view of a short length of the plated composite bicycle fork steerer tube shown in  FIG. 2 ; 
           [0043]      FIG. 5  is a top view of the bicycle fork steerer tube of  FIG. 4 ; 
           [0044]      FIG. 6  is a enlarged view of the bicycle fork steerer tube of  FIG. 5  over angular section A-A. 
           [0045]      FIG. 7  is a schematic perspective view of a short length of a plated composite bicycle fork steerer tube with an additional internal layer. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0046]      FIG. 1  is a side view of the bicycle  10 . The bicycle  10  has a frame comprising a head tube  11 , a top tube  12 , down tube  13  and a seat tube  14 . Each of the tubes is connected to one another to form a substantially closed mainframe loop. A seat post  18  supports a seat  19  at an upper end of the seat tube  14 . 
         [0047]    A fork  21  is rotatably coupled to the head tube  11  and extends through the head tube  11  carrying at an upper end the handlebars  20 . The fork  21  splits into a pair of fork arms  24  which support a front wheel  16 . 
         [0048]    An axis  28  runs longitudinally through the fork  21 . 
         [0049]      FIG. 2  is an exploded partial perspective view of the upper portions of the fork  21  and the handlebar stem  22 . The fork  21  comprises a bicycle fork steerer tube  30  with an upper end portion  31  and a lower end portion  32 , a fork crown  23  and fork arms  24 . The bicycle fork steerer tube  30  fits inside the head tube  11  of the bicycle  10 . The handlebar stem  22  is clamped to the upper end portion  31  of the bicycle fork steerer tube  30  by clamp  26  after the bicycle fork steerer tube  30  has been placed inside the head tube  11 . 
         [0050]      FIG. 3  is a perspective view of a short length of the lower end  32  of the composite bicycle fork steerer tube  30  shown in  FIG. 2 . The composite bicycle fork steerer tube  30  is disposed about a longitudinal axis  28  and has a generally cylindrical inside surface  33  and a generally cylindrical outside surface  34 . 
         [0051]    As schematically shown in  FIG. 3 , the lower end portion  32  of the bicycle fork steerer tube  30  includes a tubular layer  37  of composite material including different layers of elongated fibres some of which fibres are schematically shown to be visible through the polymer matrix. The fibres may preferably be of glass, Kevlar, carbon or other suitable material. The fibres are placed in different orientations with respect to the longitudinal axis  28  of the tube. In particular, the fibres of the tube in  FIG. 3  are selected for illustration to be placed at but three orientations, namely to be placed longitudinally, circumferentially about the tube normal to the axis  28  or in a helix about the axis  28  so as to be at 45° to the axis  28 . 
         [0052]    The fibres are placed in the different orientations since the physical properties of composite materials are generally not isotropic (independent of direction of an applied force) in nature, but rather are typically orthotropic (different depending on the direction of the applied force or load). Accordingly, the fibres in composite materials are placed in different relative quantities in different directions depending on the desire to provide relatively the resulting bending strength, hoop strength or torsion strength. 
         [0053]    When fibres are aligned with the axis  28  in a longitudinal direction, the bending strength of the tube is increased. 
         [0054]    When fibres are placed in circumferentially around the tube normal to the axis  28 , the hoop strength of the tube is increased. 
         [0055]    When fibres are placed in a helix at a 45° angle or other angles to the axis  28 , the torsion strength of the tube is increased. 
         [0056]    The directions of the fibres and the relative quantity of the fibres in each direction are adjusted depending on the strength requirements for the tube. For example, if a given bicycle fork steerer tube desired to have increased hoop strength, additional fibres may be placed circumferentially about the tube normal to the longitudinal axis. 
         [0057]    In contrast to the composite materials that are orthotropic, metals including aluminums, steel and nickel have isotropic properties and typically have the same stiffness regardless of the direction or orientation of the applied force and/or moments. 
         [0058]    The lower end portion  32  of the steer tube  30  in  FIG. 3 , is also shown with a portion  35  cut away. 
         [0059]      FIG. 4  is a perspective view of a short length of the upper end portion  31  of the composite bicycle fork steerer tube  30  shown in  FIG. 2 . The upper end portion  31  of the composite bicycle fork steerer tube  30  includes the composite tubular layer  37  identical to that of lower end portion  32 . The upper end portion  31  has an additional tubular layer  36  of plating overlying the radially outer surface of the composite tubular layer  37 . The upper end portion  31  thus has an inner composite tubular layer  37  and an outer plating tubular layer  36 . 
         [0060]      FIG. 6  is a top view of the bicycle fork steerer tube of  FIG. 4  through the upper end portion  31  best showing the composite tubular layer  37  and the relatively thin plating tubular portion  36 . 
         [0061]    The thickness of the plating tubular layer  36  may preferably be very small, for example without limitations in the range from one thousandths of an inch to 40 thousandths of an inch; preferably at least 5 thousandths of an inch. 
         [0062]    The plating tubular layer  36  of the bicycle fork steerer tube  30  is composed of a metal or metal alloy that is coupled to the outside surface while not limited, preferably the metal tubular layer  36  may be coupled to composite tubular layer  37  by a process as disclosed in the U.S. patent publication No. 2006/0160636, published Jul. 20, 2006. The plating tubular layer  36  provides protection for the outside surface  34  against damage as due to the strength and hardness of the metal or metal alloy. 
         [0063]    The plating tubular layer  36  provides resistance against wear. In particular, a bicycle fork steerer tube  30  placed within the head tube  11  of a bicycle  10  may wear against the inside of the head tube when rotated. Accordingly, the plain tubular layer  36  can provide the additional wear protection. 
         [0064]    The plating tubular layer  36  can provide additional stiffness and strength in each direction and orientation, which compliments the composite tubular layer  37  of the bicycle fork steerer tube  30 . 
         [0065]    The combination of the composite tubular layer  37  and the plating tubular layer  36  can provide the bicycle fork steerer tube to be made with desired optimal properties. For example, it is the combination of the fibres of the composite tubular layer  37 , which can be placed in a variety of directions, including axially, in a helix or circumferentially, and the plating tubular layer  36 , which creates the bicycle fork steerer tube with the strength in the required orientations. For example, if a given bicycle fork steerer tube is desired to have increased hoop strength without the desire of increased bending strength and torsion strength, the composite tubular layer  37  may be composed of fibre placed in the circumferential direction normal to the axis  28  to provide the additional required hoop strength. The composite tubular layer  37  may not need to have fibres placed in the axial direction or in a helix insofar as the required bending and torsion strength may be provided by the plating tubular layer  36 . 
         [0066]    The composite tubular layer  37  may be plated with the outer plating tubular layer  36  using a variety of manufacturing techniques including without limitation sputtering, laser ablation, inert gas condensation, oven evaporation spray conversion pyrolysis, flame hydrolysis, high energy milling, sol gel disposition and electrodeposition, dip coating, vapour disposition, vacuum deposit and electrostatic spray. These manufacturing processes are known to a person of ordinary skill in the art and many are disclosed or referred to in the U.S. patent publication No. 2006/0160636, published Jul. 20, 2006. 
         [0067]    Materials that are useful for the plating of fibre composite include (1) metals selected from the group of Ag, Au, Cd, Co, Cr, Cu, Fe, Ir, Ni, Pb, Pd, Pt, Rh, Sn, and Zn; (2) metal alloys formed of these metals; and (3) metal alloys formed of these material along with the alloying component selected from the group of B, C, Mn, Mo, P, S, Si, and W. Further disclosure can be found in the U.S. patent publication No. 2006/0160636, published Jul. 20, 2006. 
         [0068]    The plating tubular layer  36  may extend the entire length of the bicycle fork steerer tube  30  however, does not need to extend the entire length of the bicycle fork steerer tube  30  and may only need to be applied at certain locations depending on the requirements of the bicycle fork steerer tube. 
         [0069]    For example, in the arrangement where the handlebars  20  are attached to the bicycle fork steerer tube  30  plated tubular layer  36  via a clamp  26  as shown in  FIG. 2  may only be required where the clamp  26  engages the bicycle fork steerer tube  30  as shown in  FIG. 2 . Accordingly, it is not necessary for the layer of plating  36  to extend the full length of the bicycle fork steerer tube  30 . 
         [0070]    While  FIG. 2  shows the layer of plating  36  only on the upper end portion  31 , the plating tubular layer  36  may extend the entire length of the bicycle fork steerer tube. Furthermore, the plating tubular layer  36  may vary in the thickness depending on the desires for the bicycle fork steerer tube. 
         [0071]      FIG. 7  illustrates a schematic perspective view of a short length of a plated composite bicycle fork steerer tube  38  similar to  FIG. 4  with a third additional internal tubular layer  39 , preferably composed of metal or metal alloy, whether as a preferred rigid member or as another plated tubular layer.