Abstract:
A lightweight handlebar configured to be coupled to a plurality of stems is characterized by the strength of the center portion not being a maximum. Moreover, the design may be such that a single handlebar is attached between two stems, wherein the strength at a center portion that is positioned between stem attaching positions is less than the strength of the portions that are positioned toward the outsides of the stem attaching portions. Moreover, a marker for indicating unsuitability for securing to a stem may be provided at the center portion of the handlebar.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0001]    The invention relates generally to bicycle handlebars. 
       2. Description of Prior Art and Related Information 
       [0002]      FIG. 1  shows a conventional handle structure in a typical bicycle. As illustrated in  FIG. 1 , in the typical handle structure two fork legs  108 , on the left and the right, having a mechanism for steering while supporting the axle of a front wheel  114 , are connected by a fork crown  113  above the front wheel  114 . Given this, the upper portion of the fork crown  113  is connected to a single steering column, or steering tube,  111 . Additionally, the top end of the steering column  111  is connected to the handlebar  100 , at a center portion  102 , through a connecting component of a stem  109 . 
         [0003]    Moreover, the steering column  111  is borne rotatably in a front frame  17  through a head tube  10  of a front frame  17  (structured from a head tube  10 , a top tube  15 , and a down tube  16 ). Moreover, the axle of the front wheel is supported by dropouts (not shown) positioned at the bottom ends of the fork legs  108 . 
         [0004]    In this way, usually the typical bicycle handlebar is secured by a single stem at one location in the center portion thereof (for example, see Japanese Unexamined Patent Application Publication H7-300088). Because of this, the center portion of the handlebar, which serves as the position for attaching the stem, is subjected to strong loads through operation of the handle during riding. Moreover, along with the load due to operation of the handle, there are stresses because the handlebar is secured by the stem, and stresses due to the stem attaching position acting as a lever fulcrum. At these points, the center portion, which is the position in the conventional handlebar for attaching the stem, must have strength and rigidity greater than that of other portions. 
         [0005]    That is, because in existing handlebars the design assumes that the handlebar will be secured using a stem in a single location in the center portion, it is necessary to increase the strength of the handlebar overall. Therefore, the diameter of the conventional handlebar is necessarily large, and the thickness of the material also large, making the prior art handlebar heavy. 
         [0006]      FIG. 2  illustrates a handlebar that is attached to a stem in a single location in the center portion. As illustrated in  FIG. 2 , the handlebar  201  is a handlebar having a height difference between a center portion  202  and grip portions  4   a  and  4   b , where a stem attaching position  203  is provided in a single location in the center portion  202 . Because of this, if the strength of the center portion  202 , which is at the stem attaching position  203 , were reduced, then it would not be possible to maintain the strength of the handlebar. Consequently, in a handlebar of a shape wherein the stem is attached to a single location at the center portion, the structure of the present invention cannot be used. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with the present invention, structures and associated methods are disclosed which address these needs and overcome the deficiencies of the prior art. 
         [0008]    As described above, when the handlebar is secured by two stems at positions other than the center portion of the handlebar, the load that is applied to the center portion between the stems is reduced. So a reduction in strength, stiffness and/or durability of the center portion of the preferred handlebar will not cause problems. However, because a conventional handlebar is manufactured without discriminating between the locations where strength, stiffness or durability is and is not required, the wall thickness of the material is thick even at locations that do not require strength, stiffness or durability, which wastes material and adds weight. 
         [0009]    As used herein, “stiffness” is a relative term. When an element (such as a portion of a handlebar) exhibits less temporary deformation while a given force is applied, this element is considered “stiffer” than another such element. 
         [0010]    As used herein, “Strength” is a relative term. When an element (such as a portion of a handlebar) exhibits less permanent deformation for a given force (applied once and then removed), this element is considered “stronger” than another such element. Moreover, when an element withstands a greater force (applied once and then removed) before it exhibits any measurable permanent deformation, it is considered “stronger” than another such element. 
         [0011]    As used herein, “durability” is a relative term. When an element (such as a portion of a handlebar) exhibits less permanent deformation for a given cycle of force (repeatedly applied and removed), this element is considered “more durable” than another such element. Likewise, when an element withstands a greater number of cycles of force (repeatedly applied and removed) before it exhibits any measurable permanent deformation, this element is considered either “more durable” or “stronger” than another such element. 
         [0012]    For simplicity, the term “strength”, as used herein below, may generically refer to “stiffness”, “Strength” and/or “durability” as defined above. 
         [0013]    When an element, such as a portion of a handlebar, has an ability to resist a greater force before failure, this portion of the handlebar may have a greater “stiffness”, a greater “Strength”, and/or a greater “durability” as compared to another element. This force could include, for example, shear, axial, bending, moment and twisting moment. Various forces may be used to determine “stiffness”, “Strength” and/or “durability” of a particular portion of the handlebar. Failure could refer to any change in the element, such as deformation, bending, twisting, breaking, separating, or the like. 
         [0014]    In contemplation of the situation described above, the object of the present invention is to provide a handlebar that is able to achieve a reduction in weight while maintaining strength and rigidity when secured by a plurality of stems. 
         [0015]    In order to solve the problem set forth above, in the handlebar according to the present invention the strength of the center portion is not at a maximum. As described above, when the handlebar is secured by two stems, respective stems are attached to positions that have predetermined distances to the left and the right of the center portion, rather than attaching a stem to the center portion of the handlebar. In the stem attaching positions there is the need for high strength and rigidity due to the application of the stresses caused by the handlebar being secured by the stem and the stresses applied through the attaching position for the stem acting as a lever fulcrum. However, on the other hand, these loads do not act on the center portion positioned between one stem and the other, so the strength of the center portion may be reduced to some degree since there is no need for the strength of the center portion to be at a maximum. 
         [0016]    Moreover, the handlebar according to the present invention may be coupled to two stems, while the strength of a center portion between stem attaching portions may be less than the strength at a handlebar portion positioned to the outer side of the stem attaching portions. 
         [0017]    Here the strength of the center portion of the handlebar not being high is because, rather than the handlebar being secured by a single stem, it is secured by two stems, provided at the top ends of the left and right fork legs, so that all that is necessary is to be formed with high strength at the securing locations. A similar strength material may also be used from the securing locations to both end portions. The methods for increasing strength may comprise increasing the outer diameter of the pipe, increasing the thickness of the pipe material, or using a material with high strength. Moreover, the method for increasing strength may be that of adding a reinforcing material. Specifically, the method may be one wherein a plate member is inserted into the pipe, or wherein the empty cavity of the pipe is filled. 
         [0018]    In the handlebar according to the present invention, a marker for indicating unsuitability for securing a stem may be provided on the center portion positioned between the two stem attaching portions. If a high-strength portion and a low-strength portion are provided in the handlebar, and the stem is attached accidentally to the low-strength portion, there the handlebar might bend, or the like, during riding, which could cause an accident. Given this, a marker is provided at the low-strength location displaying that the location is unsuitable for attaching to the stem. 
         [0019]    The marker may comprise printing indicating unsuitability for attachment, a sticker, one or more colors different from the colors of other portions, or a cross-sectional shape unsuitable for securing to a stem. 
         [0020]    The center portion of the handlebar according to the present invention may be structured so as to be unsuitable for securing to a stem. 
         [0021]    Here the structure that is unsuitable for securing may be one wherein the cross-sectional shape is not a circle or a regular polygonal (i.e., equal length sides and equal angles). The cross-sectional shape may have dimensions different from an existing standard dimension. The cross-section may also be non-uniform in the lengthwise direction of the handlebar. Because there is a standard for stems, forming the cross-sectional shape of the center portion of the handlebar with a shape that does not fit with the standard, as described above, makes attachment difficult, thereby preventing accidental attachment of the stem to a weaker location. 
         [0022]    In the handlebar according to the present invention, a portion other than the center portion may be formed with a larger pipe outer diameter, with a thicker wall thickness of the pipe material, or with a material of a higher strength, when compared to that of the center portion. 
         [0023]    Moreover, in the handlebar according to the present invention, a reinforcing material may be added to portions other than the center portion. 
         [0024]    The handlebar according to the present invention has a reduced weight while preserving strength and rigidity when the handlebar is secured to a plurality of stems. 
         [0025]    In summary, a lightweight handlebar configured to be coupled to a plurality of stems is characterized by the strength of the center portion not being at a maximum. 
         [0026]    Moreover, the design may be such that a single handlebar is attached between two stems, wherein the strength at a center portion that is positioned between stem attaching positions is less than the strength of the portions that are positioned toward the outsides of the stem attaching portions. Moreover, a marker for indicating unsuitability for securing to a stem may be provided at the center portion of the handlebar. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a perspective view of a prior art handlebar in a typical bicycle. 
           [0028]      FIG. 2  is a perspective view of a prior art handlebar attached to a stem at one location. 
           [0029]      FIG. 3  is a structural diagram of a handlebar according to a first embodiment. 
           [0030]      FIG. 4  is an enlarged view of the left side of a handlebar according to the first embodiment. 
           [0031]      FIG. 5  is a diagram ( 1 ) of the attached state of the handlebar according to the first embodiment. 
           [0032]      FIG. 6  is a diagram ( 2 ) of the attached state of the handlebar according to the first embodiment. 
           [0033]      FIG. 7  is a diagram of the attached state of a handlebar according to a second embodiment. 
           [0034]      FIG. 8  is a diagram of the attached state of the handlebar according to an exemplary embodiment. 
       
    
    
       [0035]    The invention and its various embodiments can now be better understood by turning to the following detailed description wherein illustrated embodiments are described. It is to be expressly understood that the illustrated embodiments are set forth as examples and not by way of limitations on the invention as ultimately defined in the claims. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    Preferred embodiments according to the present invention will be described in detail below, referencing the drawings. Note that the scope of the present invention is not limited to the embodiments or drawings set forth below, but rather may be altered and modified in many ways. 
         [0037]      FIG. 3  illustrates a first preferred embodiment of a handlebar apparatus, or simply handlebar,  1  configured to be attached to stems at two locations. As illustrated in  FIG. 3 , the handlebar  1  comprises a center portion  2 , stem attaching portions  3   a  and  3   b , grip portions  4   a  and  4   b , and bent portions  5   a  and  5   b , where the bent portions  5   a  and  5   b  are provided so as to elevate the grip portions  4   a  and  4   b  when attached to the stem. While a particular shape for the handlebar  1  is shown, including bent portions  5   a  and  5   b , the present invention may include handlebars of various shapes, with or without bent portions  5   a  and  5   b , or with bent portions  5   a  and  5   b  having various and different bends formed therein. 
         [0038]    Unlike the prior art handlebar, the preferred handlebar  1  is configured to be coupled to stems at two locations. Thus the strength will be adequate if the stem attaching portions  3   a  and  3   b  are attached securely, and the handlebar  1  is formed so as to have high strength from the stem attaching portions  3   a  and  3   b  to both end portions. 
         [0039]      FIG. 4  presents an enlarged view of the left side of the first preferred embodiment of the handlebar  1 . As illustrated in  FIGS. 3 and 4 , in the handlebar  1 , no difference in thickness is provided on the outer surface  6   a . However, as illustrated in  FIG. 4 , a difference in thickness is provided in the inner surface  6   b , to cause uneven portions at the boundaries between the center portions  2  and the attaching portion  3   a  and  3   b.    
         [0040]    Moreover, the thickness  7   b  of the stem attaching portion  3   b , the thickness  7   c  of the bent portion  5   b , and the thickness  7   d  of the grip portion  4   b  are thicker than the thickness  7   a  of the center portion  2 . This is because although strength is required from the stem attaching portions  3   a  and  3   b  to the grip portions  4   a  and  4   b , because the handlebar  1  is attached to stems at the stem attaching portions  3   a  and  3   b , no load acts on the center portion  2 . Therefore, not as much strength is required in the center portion  2 . Moreover, a weight reduction can be achieved, and raw materials costs can also be reduced, through having the center portion  2  be thin. 
         [0041]    The thickness and diameter of the handlebar  1 , including the center portion  2 , stem attaching portions  3   a ,  3   b , and the grip portions  4   a ,  4   b  may vary according to material and application. For example, tubing diameters from about 22.2 mm to about 31.8 mm may be used for one or more of the components of the handlebar  1 . In some embodiments, the tubing diameters may be constant among each component (such as the center portion  2 , stem attaching portions  3   a ,  3   b , and the grip portions  4   a ,  4   b ), and in other embodiments, the tubing diameters may vary between the components. For example, the tubing diameters in the grip portions  4   a ,  4   b  may be less than 22.2 mm. The present invention contemplates tubing diameters described above as well as variations thereof. The tubing thickness may also vary depending on material and application. For example, steel tubing may be about 1.0 mm thick while aluminum may be about 0.7 mm or more in thickness. Of course, the present invention contemplates tubing thicknesses described above as well as variations thereof. 
         [0042]      FIGS. 5 and 6  are operative views of the first preferred embodiment of the handlebar  1  attached to a bicycle.  FIG. 5  is a front perspective view of the front fork and handlebar  1 . In the first preferred handle structure  1 , a steering column  11  that is borne rotatably on a head tube  10  of a front frame  17 , and left and right fork legs  8   a  and  8   b , are provided attached, in parallel, on the left and right of the steering column  11 . The axle of the front wheel  14  is borne rotatably by dropouts (not shown) on the bottom ends of the left and right fork legs  8   a  and  8   b . The top ends of the left and right fork legs  8   a  and  8   b  protrude adequately upward from the position of the top end  11   a  of the steering column  11 . Two stems  9   a  and  9   b  are attached to the respective top ends of the left and right fork legs  8   a  and  8   b , and a single handlebar apparatus  1  is coupled to these two stems  9   a  and  9   b.    
         [0043]      FIG. 6  is a rear perspective view of the front fork and handlebar apparatus  1 . 
         [0044]    The left and right fork legs  8   a  and  8   b  protrude above the top end  11   a  of the steering column  11 , through holes provided in the left and right end portions of a fork crown  13   a . The two stems  9   a  and  9   b  are provided on the top ends of the left and right fork legs  8   a  and  8   b . Given this, the handlebar  1  is secured to the top ends of the left and right fork legs  8   a  and  8   b  by the two stems  9   a  and  9   b  at the stem attaching portions  3   a  and  3   b.    
         [0045]      FIG. 7  is a rear perspective view of a second preferred embodiment of a handlebar apparatus  301 . As illustrated in  FIG. 7 , the handlebar apparatus  301  is formed from a center portion  302 , stem attaching positions  303   a  and  303   b , grip portions  304   a  and  304   b , and bent portions  305   a  and  305   b , similar to the first preferred embodiment of the handle apparatus  1 . 
         [0046]    However, unlike the first embodiment, a marker  318  is provided in the center portion  302 , indicating that the center portion  302  is a part where the strength is weak. The marker  318  is provided through providing a pattern that is different from other portions; however, the marker  318  may instead comprise printing indicating unsuitability for attachment, a sticker, coloring different from other portions, or a cross-sectional shape that is unsuitable for attachment to a stem. 
         [0047]    The stems  309   a  and  309   b  are attached to stem attaching portions  303   a  and  303   b  where there is no marker  318 . The provision of this marker clearly distinguishes the strong portions from the weak portions, making it possible to prevent a stem from being connected to a weak portion by accident. 
         [0048]      FIG. 8  shows an exemplary embodiment of the present invention where a center portion outer diameter  2   d  may be less than at least one of a grip portion outer diameter  4   d , a stem attachment portion outer diameter  3   d  and a bent portion outer diameter  5   d.    
         [0049]    The preferred handle apparatuses are useful for sports use, used by bicycle users who attach and remove handlebars. 
         [0050]    Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of examples and that they should not be taken as limiting the invention as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the invention includes other combinations of fewer, more or different ones of the disclosed elements. 
         [0051]    The words used in this specification to describe the invention and its various embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification the generic structure, material or acts of which they represent a single species. 
         [0052]    The definitions of the words or elements of the following claims are, therefore, defined in this specification to not only include the combination of elements which are literally set forth. In this sense it is therefore contemplated that an equivalent substitution of two or more elements may be made for any one of the elements in the claims below or that a single element may be substituted for two or more elements in a claim. Although elements may be described above as acting in certain combinations and even initially claimed as such, it is to be expressly understood that one or more elements from a claimed combination can in some cases be excised from the combination and that the claimed combination may be directed to a subcombination or variation of a sub combination. 
         [0053]    Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements. 
         [0054]    The claims are thus to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, what can be obviously substituted and also what incorporates the essential idea of the invention.