Abstract:
The main structural portions of the frame are standardized and are assembled without welding therebetween, thereby enabling a reduction in the number of components, a simplification of manufacturing processes, and simple attachment and detachment of various types of security components and accessory components. An extruded material or a molded material having an integrally molded structure is cut into required lengths and screwed to one another to form the main structural portions. As a result, the frame is assembled without welding the main structural portions themselves and the main frame is simultaneously made to be a structure of a single bar having no joint, which distributes a load and realizes the body without using a truss structure. Furthermore, a concave groove is formed in the integrally molded structural material, and is used to screw or insert the security components and accessory components, which simplifies attaching and detaching of the components.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a bicycle that is readily manufactured, disassembled/assembled, and mounted with add-on components. 
       BACKGROUND OF THE INVENTION 
       [0002]    Bicycles have been familiar means of transportation used widely since the 20th century. Accordingly, a variety of bicycles are manufactured depending on their purpose. The principal portion of the bicycle is the main frame serving as a foundation supporting the entirety. The bicycle is made up of a saddle portion on which a human being sits, a front fork to which a front wheel and a handle changing a travel course are attached, pedals generally rotated by the feet, a chain and a gear transmitting the power of the pedals to a rear wheel, and the rear and front wheels. 
         [0003]      FIG. 1  shows a correlation view of supporting points when a bicycle frame is viewed from the side. Basically, a front wheel shaft  91 , a rear wheel shaft  92 , and a seating point  94  support a weight of a bicycle and its rider. A crank shaft  93  and a steering shaft  95  for steering the bicycle are added to these. Accordingly, as shown in  FIG. 1A , these may be basically linked by one rod. When a load is applied, stress is concentrated on a junction C with the rod linked to the crank shaft, and the junction becomes a structural weak point in terms of strength. 
         [0004]    Accordingly, as shown in  FIG. 1B , most of the real bicycles are configured to form a frame of a so-called diamond truss structure across a structure between the seating point  94  and the rear wheel shaft  92  and between the seating point  94  and the steering shaft  95 , thereby increasing overall strength. To avoid making contact with clothing or to facilitate getting on/off, the structure between the seating point  94  and the steering shaft  95  may be omitted. In this case, measures to increase the strength between the crank shaft  93  and the steering shaft  95 , for example making the structure thick or forming two structures, may be used. 
         [0005]    The bicycle is desirably lightweight to provide movement based on human power. However, to manufacture the frame of the diamond truss widely employed in order to reduce weight and to increase rigidity, as shown in  FIG. 1 , it is necessary to weld many members to provide connections or to assemble many members using many bolts/nuts. As such, the complexity and extension of the manufacturing process are obstacles to decreasing the manufacturing cost. Further, to attach various security components/accessory components, specific bolts/nuts should be used, and specialized tools and skilled work are required. Thus, the presence of a technical engineer is essential in many cases, and no one can perform the attachment work. Accordingly, this is an obstacle to the attaching/detaching and distribution of security components and/or accessory components. 
       RELATED ART DOCUMENTS 
     Patent Document 
       [0000]    
       
         Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-106521 
       
     
       Non-Patent Document 
       [0000]    
       
         Non-Patent Document 1: Goro Imura, et al., Bicycle &amp; Machine Elements, published by INAX 
       
     
         [0008]    Since a large number of components and frequent bonding work such as welding are required to manufacture the bicycle, it is difficult to further reduce the manufacturing cost, and specialized tools and skilled work are required to attach the security components and/or accessory components. These are the problems to be solved. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is mainly characterized in using an integrally molded structural material having the same cross section in whole or for the most part for the main portions of a frame, assembling these main portions with screws, and easily attaching security or accessory components to the integrally molded structural material. 
         [0010]    The concept of the present invention will be briefly described in  FIG. 2  when the bicycle frame is viewed from the side. A steering shaft  95  and a rear wheel shaft  92  are linked by one rod having basically a linear shape, i.e., a main frame  1 , and a seating point  94  and a crank shaft  93  are linked to this main frame  1 . Thereby, even when force is applied to the main frame  1  from the seating point  94  and the crank shaft  93 , the main frame  1  receives stress as a whole, so that deflection as indicated by a dotted line in  FIG. 2 , particularly without stress concentration, occurs. To realize this, the main frame  1  is configured so as to be able to easily attach or detach various structural components. 
       Advantageous Effects 
       [0011]    Since the main portions of the frame are integrally molded structural materials having the same cross section for the most part, the number of components can be significantly reduced, and the main portions can be assembled by screws without carrying out bonding work such as welding. As such, manufacturing, transportation, and inventory control are easy and greatly contribute to lowering the cost. Simultaneously, since the main frame has the shape of an integrated rod with no junctions, a load is distributed without being concentrated on any one place during travel. For this reason, a frame that is light weight and highly durable can be manufactured without using a truss structure. Further, due to there being no need for specialized tools, anyone can easily carry out repair and disassembly. Further, since security or accessory components are attached in a set-in type or in a screwing type, there is the advantage of a significant simplification of the work being possible. Accordingly, after the purchase of a bicycle, by changing the attachment positions of the main structural portions or by exchanging them for different components, reconstruction is possible according to a change in the physical size or purpose of a user. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is an explanatory view of a basic structure of a conventional bicycle. 
           [0013]      FIG. 2  is an explanatory view showing a basic structure of a bicycle of the present invention. 
           [0014]      FIG. 3  is an explanatory view showing a method of carrying out the present invention (Embodiment 1), in which  FIG. 3A  is a left side view,  FIG. 3B  is a right side view, and  FIG. 3C  is a front view. 
           [0015]      FIG. 4  is an explanatory view showing one embodiment of a main frame of the present invention, in which  FIGS. 4A and 4B  are perspective views, and  FIGS. 4C and 4D  are cross-sectional views. 
           [0016]      FIG. 5  is an explanatory view showing one embodiment of a slide joint of the present invention. 
           [0017]      FIG. 6  is an explanatory view showing one embodiment of a seat joint of the present invention. 
           [0018]      FIG. 7  is an explanatory view showing one embodiment of a frame end of the present invention. 
           [0019]      FIG. 8  is an explanatory view showing one embodiment of an end plug joint of the present invention. 
           [0020]      FIG. 9  is an explanatory view showing one embodiment of a method of fixing a plug clamp of the present invention. 
           [0021]      FIG. 10  is an explanatory view showing one embodiment of a plug joint of the present invention. 
           [0022]      FIG. 11  is an explanatory view showing one embodiment of a head joint of the present invention, in which  FIG. 11A  is a perspective view, and  FIG. 11B  is a top plan view. 
           [0023]      FIG. 12  is an explanatory view showing one embodiment of a snap-on joint of the present invention. 
           [0024]      FIG. 13  is an explanatory view showing a folding bicycle according to one embodiment of the present invention (Embodiment 2). 
           [0025]      FIG. 14  is an explanatory view showing a folding joint of the folding bicycle of the present invention. 
           [0026]      FIG. 15  is an explanatory view showing a bicycle for children according to one embodiment of the present invention (Embodiment 4). 
           [0027]      FIG. 16  is an explanatory view showing a sports bicycle according to one embodiment of the present invention (Embodiment 5). 
           [0028]      FIG. 17  is an explanatory view showing a split-type bicycle according to one embodiment of the present invention (Embodiment 3). 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    An object of manufacturing a bicycle by making up a frame of main structural portions, which are not welded to each other, to reduce the manufacturing processes and by facilitating attaching or detaching of security components and accessory components to provide simple maintenance is realized by means of incorporating an extruded metal material such as aluminum or a synthetic resin or a molded material of a fiber-reinforced synthetic resin, which has sufficient strength and can resist bending and twisting using screws. Further, if a groove is formed in this extruded material, the security components and the accessory components are more easily attached or detached. 
       Embodiment 1 
       [0030]      FIG. 3  is a configuration view showing a concrete image of the entirety of the present invention, in which all of a main frame  1 , a front fork  2 , and a seat pipe  3  use an integrally molded structural material showing a side and a cross section in  FIG. 4 , particularly an extruded material of metal such as aluminum or a synthetic resin or a molded material of a fiber-reinforced synthetic resin. A case in which no groove is formed in the extruded material is shown in  FIGS. 4A and 4C , whereas a case in which grooves are formed in the extruded material is shown in  FIGS. 4B and 4D . 
         [0031]    In the embodiment shown in  FIG. 3 , a rear wheel  6  is joined to the main frame  1 , and the front fork  2  is joined to the main frame  1  via a joint  40 . A seat pipe  3  is joined on an upper side of the main frame  1 , and a bottom bracket  4  holding a rotational shaft of cranks  12  is joined on a lower side of the main frame  1 . 
         [0032]    Further, in the embodiment shown in  FIG. 3 , the main frame  1  and the front fork  2  are shown to use the same component, because they are completely equal to each other in total length and position of a bent part. In a case in which the same component may be used, this has the effect of reducing the number of components. Further, the seat pipe  3  is also the same integrally molded structural material, and is not provided with a bent part  20  because the bent part  20  is not required. 
         [0033]    In the bicycle shown in  FIG. 3 , to support the wheel in a cantilever form, the bent part  20  is provided. However, in principle, a straight frame is also possible. In this case, even when a position of the center of gravity of one body of a person and a bicycle is vertically located above a contact of the wheel with the ground, the front fork is not always perpendicular to the ground. However, this is insignificant in actual practice. 
         [0034]    Further, the term used to denote the front fork is thought to have been derived from that of a front end that branches off like a fork used as tableware. However, the front fork  2  of the present invention has an integrated shape, and strictly speaking, this term is not suitable for it. However, since a pipe supporting the front wheel is generally called a front fork, the term “front fork” was settled upon and is used in the description of the present invention for the sake of convenience. 
         [0035]    The other components, for instance components indispensable to travelling such as a driving device based on front and rear wheels  5  and  6 , pedals  9 , a chain  10 , and cranks  12 , a handle  8 , and a brake  11 , are the same as those of the common bicycle. 
         [0036]    Further, as shown in  FIGS. 4C and 4D , the integrally molded structural material includes a hollow part  22 . Further, an embodiment in which concave grooves having openings  23  facing outward in opposite ends are formed is also shown at the same time. The main frame  1 , the front fork  2 , and the seat pipe  3  are incorporated by screws regardless of whether the groove is present. The hollow part  22  is not always essential. However, since the strength to resist bending and twisting is increased when a pipe of the same weight is generally hollow and increased in diameter, a hollow pipe is widely used. 
         [0037]    Further, this hollow part  22  may be used for the purpose of storing various components. For example, a battery supplying power to various electrical components, or an electronic device such as a navigation system or a radio may be stored therein. Then, a structure subject to small irregularities and thus associated with a lower fear of failure caused by unexpected shocks may be realized. 
         [0038]    Since the main frame  1  is connected with the seat pipe  3  and the bottom bracket  4  with high strength, a slide joint mainly shown in  FIG. 5  is used. The case in which no grooves are formed in the extruded material is shown in  FIG. 5A , whereas the case in which the grooves are formed in the extruded material is shown in  FIG. 5B . With the grooves, an inner plate nut  30  is slid into each groove of the main frame  1 , and a base  31  is covered from the outside of the main frame  1  and is fastened by connection screws  32 . Thereby, the inner plate nut  30  is incorporated with the base  31 . If one end of the seat pipe  3  is joined to the portion of the base  31 , the structure shown in  FIG. 3  may be realized. Further, by unfastening the connection screws  32 , the base  31  may be slidably displaced, so that a fixing position can be changed depending on the physical size. Simultaneously, an effect of reinforcing the main frame  1  can be also expected thanks to the base  31 . 
         [0039]    The inner plate nut  30  of  FIG. 5  may also be placed and inserted from an upper portion of the groove. As such, even after the entire bicycle has been assembled, the security and accessory components may be incorporated at any portion of the groove in an add-on fashion. Accordingly, the degree of freedom in attaching or detaching the security and accessory components can be increased, and the work time can be remarkably shortened. 
         [0040]    Further, to attach the saddle  7 , a seat post  34  distributed generally may be used. As such, if the saddle  7  is inserted into the hollow part  22  of the seat pipe  3  of the integrally molded structural material shown in  FIG. 4  and is fastened from the periphery, a height of the saddle  7  may be freely adjusted to the height of a rider. 
         [0041]    A method of attaching the saddle  7  when the hollow part  22  is present in the seat pipe  3  is shown in  FIG. 6 . The seat post  34  extending from the saddle  7  is inserted into the hollow part of the seat pipe  3 , and a saddle fixing screw  35  on a seat clamp  82  attached to the seat pipe  3  is fixedly fastened. 
         [0042]    When a cross section formed by cutting the integrally molded structural material is exposed, there is a possibility of dirt entering or contaminating the end of the main frame  1  or the front fork  2 . As such, an end cap  36  as shown in  FIG. 7  is fixed to the end of the main frame  1  or the front fork  2  by cap fastening screws  37  inserted into cap fastening holes  38 . The cap fastening screws  37  are fastened by threading through-holes  33  formed in the frame. Further, the end cap  36  may function as a base for attaching an accessory component(s), which has a separate function such as a transmission or a reflector, to the frame end. 
         [0043]    Additionally, when the concave grooves  21  are formed in the main frame  1  or the front fork  2 , and in the seat pipe  3 , there is a fear of dirt entering and collecting on the concave grooves  21  in proportion to the period of outdoor use. Accordingly, in accordance with the embodiment of the present invention, this problem is solved by covering a groove cover  60  formed of a soft material such as rubber or synthetic resin on each groove. Set-in ridges  61  are formed on the groove cover  60 . These ridges are fitted into the cover set-in grooves  39  shown in  FIG. 7 . Thereby, the groove cover is adapted to be prevented from coming off by itself as long as a strong force is not applied. Without the concave grooves  21 , the groove covers are not required. 
         [0044]    Thus, even when the main frame  1  used for the description of the present invention basically has any cross section, the present invention can be realized. However, if the concave grooves are formed in the main frame as described below, the object of the present invention can be more easily realized. 
         [0045]    Further, the above description has been made of the case in which the concave groove has a wider inner portion than the opening. When the interior is wide, this is excellent because there is no danger of the connection components coming off even in an unanticipated situation in which the screws are unfastened. In principle, even when the opening and the interior have the same width, or even when the interior is narrower, the present invention can be carried out. In this case, the concave groove can be more easily formed, but a study into exerting a sufficient fixing force is required, or a thorough daily check should be done in order to cope with a contingency in which the screws becomes loose. 
         [0046]    To fix a component such as a saddle  7  or a handle  8  attached to the end of the frame, an end plug joint  80  shown in  FIG. 8A  is used. The end plug joint  80  is fixed to the main frame  1  by a hollow setscrew  81 . A screw hole into which the hollow setscrew  81  is inserted is located at a portion where the end plug joint  80  is inserted into the concave groove  21 . By fastening the hollow setscrew, the main frame  1  is pressed to produce a fixing force. Alternatively, the hollow setscrew  81  may be provided with a head, and pass through the main frame  1  to prevent it from coming off. In the figure, the case of the main frame  1  is shown. However, if the main frame  1  is replaced by the front fork  2  or the seat pipe  3 , the present invention may be similarly carried out. The shape of a tip is changed based on this structure, so that a seat clamp  82  for fixing the seat post  34  as shown in  FIG. 8B  or a handle clamp  83  for attaching the handle  8  as shown in  FIG. 8C  can be manufactured. 
         [0047]    Meanwhile, to fix the main component such as the seat post  34  or the accessory component, a plug clamp  84  as shown in  FIG. 9  as one embodiment of the present invention may be used rather than the structure as if fastened from the periphery. This is to press a pressing part  88  that is a part of the plug clamp  84  against the fitted the seat post  34  and an attaching part  90  other than the seat post by fitting the plug clamp  84  into the main frame  1  having a cutout part  89  so as to allow the plug clamp  84  to be inserted and by fastening a fixing screw  87  through a fixing screw hole  85  formed in the plug clamp  84 , and thus fix the seat post  34  and the attaching part  90  using frictional force. 
         [0048]    In the case of this structure, a hollow setscrew hole  86  is formed on the opposite side of the fixing screw hole  85 , and the hollow setscrew  81  is fastened. Thereby, the main component such as the seat post or attaching part  90  such as the accessory component can be prevented from coming off. Alternatively, in place of the hollow setscrew hole  86 , the same fixing screw hole  85  may be formed, and the fixing screws  87  may be fastened from the left and right sides or from the upper and lower sides. Which method is used may be selected depending on the required strength with which an attaching component is attached. 
         [0049]    To connect the front fork  2  and the main frame  1 , a plug joint  40  shown in  FIG. 10  is used. The joint  40  is fixed by connection screws  32 . Portions of the joint  40  which are fitted into the concave groove  21  and the hollow part  22  of the main frame  1  are mutually pulled to press the main frame  1  by fastening the connection screws  32 , thereby exerting a fixing force. Further, it is sufficient if an end of the main frame  1  is cut at a right angle. Not only is the workability also increased because welding of a large component is not required, but the number of components is reduced to facilitate inventory control by standardization as standard goods. 
         [0050]    A head clamp  70  shown in  FIG. 11  is coupled with the front fork  2  by connection screws  32 , and is simultaneously coupled with a steering shaft  72  passing through a head joint  71 . The steering shaft  72  is rotated in the head joint  71 , thereby moving the front fork  2  to allow a steering operation to be performed during travel. Further, when the concave groove  21  is formed in the front fork  2 , the head clamp  70  is shaped so as to be caught in the groove. Thereby, although the connection screws  32  have become loose, the risk of the head clamp  70  coming off is low. 
         [0051]    The front fork  2  and the head clamp  70  are fixed by the connection screws  32 . However, since an attaching hole is made in an arbitrary portion using an attaching hole previously made in the front fork  2  as well as the guide groove  62 , the position of attachment may be changed so as to be appropriate to the rider&#39;s physical size or intended use. Even when a screw hole is made in the future, there is a low risk of being out of center because the guide groove  62  guiding a drill is formed. Alternatively, in place of the front fork  2 , the front fork of a bicycle that is generally distributed may be attached to the head joint  71 , thereby constituting the frame. 
         [0052]    Additionally, even when any set of the head joint  71  and the main frame  1  and the head clamp  70  and the front fork  2  are joined by welding without using the screws, the other set can be attached/detached by the connection screws  32 . As such, the effect of the present invention can be brought about, whereby the main portions of the frame can be dissembled/assembled by the screws. 
         [0053]    Typically, when a person gets on and travels, there is sometimes the application of strong vibrations or a sudden force. As such, a sufficient amount of strength is required to connect the main frame  1 , the front fork  2 , and the seat pipe  3 . For this reason, the connection components previously shown in  FIGS. 5 and 8  are required. However, when the security components and accessory components, to which a weak force is applied compared to the human body, are attached to the frame having the concave grooves, an easier method can be realized using these grooves. 
         [0054]    These are a claw-shaped snap-on joint  41  and a wire-shaped snap-on joint  42 , both of which are shown in  FIG. 12 . The claw-shaped snap-on joint  41  is designed to be caught in the concave groove  21  by protruding claws, and is mounted by pushing from the upper side. If the claw-shaped snap-on joint  41  is manufactured to have a size big enough to withstand a load, a variety of applications such as a head light, a mudguard, a holder, etc. may be considered. 
         [0055]    The wire-shaped snap-on joint  42  is manufactured so that the thickness of the wire and the length of a plug part are appropriate for the intended use, and thereby various applications may be considered. Particularly, the wire-shaped snap-on joint  42  has the effect of attaching a component such as a carrier or a cargo that is generally made of a metal wire. 
         [0056]    When the dimensions of these grooves are standardized, the third-party sale of accessories based on a variety of claw-shaped snap-on joints and wire-shaped snap-on joints can be expected, this being seen as a ripple effect. However, in the case of a component having a high load, it is preferable to also use screwing in combination, using the inner plate nut  30  shown in  FIG. 5 . Further, the example in which the main frame  1  is used as a set-in place of the claw-shaped snap-on joint  41  or the wire-shaped snap-on joint  42  is shown. However, the snap-on joint may also be set in the other portion having the same groove, for instance the front fork  2  or the seat pipe  3 . 
       Embodiment 2 
       [0057]    A folding bicycle to which the present invention has been applied is shown in  FIG. 13 . Since the main frame  1  and the front fork  2  are simple integrally molded structural materials, these are cut halfway, and the cut portions are interconnected by a folding joint  50  shown in FIG.  14  and connection screws  32 . Then, the bicycle that can be folded at this portion as shown in  FIG. 13  can be realized. In the description of this embodiment, a frame with grooves is used. This embodiment may be similarly applied to a case without grooves. In the case of the frame with grooves, the folding joint  50  can be easily manufactured by applying a structure having the plug joint  40  shown in  FIG. 10 . In  FIG. 13 , an example in which the handle  8  is also folded is shown. However, if necessary, whether to fold the handle may be selected. 
         [0058]    The advantage of the present invention is that a previously purchased bicycle, which is not a folding type based on the present invention, can be simply reconstructed into the folding type in the future as needed. The main frame  1  and the front fork  2  are cut by a typical metal cutter, and the cut portions may be interconnected using the folding joint  50  and the connection screws  32 . Further, when holes giving passage to the connection screws  32  are formed, the guide groove  62  may be used, thereby reducing the risk of it being off-center. This is one of the great advantages of the present invention which is that professional skill such as welding and installations are not required. 
       Embodiment 3 
       [0059]    Another embodiment of the present invention is shown in  FIG. 17 . Main coupling portions of the frame, and one or both of a coupling part of the main frame  1  and the front fork  2  and a coupling part of the main frame  1  and the seat pipe  3  are replaced by split joints  51 , each of which is splittable without using a tool. Thereby, an effect similar to the folding type in which the frame is easily split, and is housed and carried in a compact fashion, can be realized. The joint of each part may be easily replaced by the split joint  51  using the coupling structure of the frame material and the joint based on the screws described in Embodiment 1. 
       Embodiment 4 
       [0060]    Another embodiment of the present invention is shown in  FIG. 15 . This is used for an infant, is not provided with the driving apparatus based on the pedals and the chain, and travels by kicking. The structure is simpler, and there are two main structures, the main frame  1  and the front fork  2 . In the description of this embodiment, the frame having the concave grooves is used. However, this embodiment may be similarly applied to a case without grooves. 
         [0061]    If the handle is formed in the same plug type as the saddle as shown in  FIG. 6 , its height can be freely changed. As such, the height can not only be sequentially increased in proportion to the growth of a child, but the driving apparatus based on the pedals and the chain can be attached in the future. Thus, the bicycle can be reconstructed into a typical pedal-driven bicycle. Alternatively, the main frame  1  and the front fork  2  may be exchanged for large-size members by converting the joint  40 , and thereby it is possible to cope with a change in physical size. This is also one of the advantages of the present invention that can be configured using only the screws and connection components without using welding. 
       Embodiment 5 
       [0062]    The present invention can deal with a variety of purposes by previously preparing frames having different dimensions, and selecting and assembling the frames by request, because very simple frames are configured to be connected using screws. This provides a great advantage in terms of inventory control. For example, a sports bicycle is shown in  FIG. 16 . In this sports bicycle, a diameter of the wheel is increased while the height above ground of the driving apparatus configured of the pedals and the chain is maintained, so that a bicycle suitable for high-speed travel can be made. In the description of this embodiment, a frame having concave grooves is used. However, this embodiment may be similarly applied to a case without grooves as previously described. 
       Embodiment 6 
       [0063]    So far, in the description of the present invention, a two-wheel vehicle having a front wheel and a rear wheel has been used. However, if any one of the front wheel and the rear wheel is formed using two wheels, a three-wheel vehicle may be made. Further, if the front wheel and the rear wheel are formed using two wheels, a four-wheel vehicle may be made. In these cases, the vehicle can be realized by expanding a wheel shaft of the two-wheel portion and connecting the two wheels to opposite ends of the expanded shaft, or by coupling two frame parts configured based on the main frame  1  in parallel left and right. Accordingly, the present invention is not limited to the two-wheel vehicle. Further, in this case, since it is sufficient if one or both of the front wheel and the rear wheel are added to the wheel shaft in the future, the main frame, the seat pipe, and the front fork may be converted. 
         [0064]    However, when the two wheels are mounted on any wheel shaft, this shaft is always parallel to the ground. As such, the structure of this wheel shaft must be inclined or flexible when performing a turnabout. 
       Embodiment 7 
       [0065]    In the above embodiment of the present invention, a bicycle in which the pedals are driven by human power is given. As another embodiment of the present invention, there is a power assistant based on an electric motor as an external power unit. A mechanism capable of applying power of the electric motor via the bottom bracket  4  is attached to the main frame  1 , and a signal of a torque sensor detecting a pedal force to the pedals is processed. If a motorized force corresponding to the pedal force is transmitted to the real wheel via the crank shaft and the chain  10 , this becomes a motorized assistant bicycle. 
         [0066]    In addition to the electric motor, a battery supplying power to the motor, a switch turning on or off the power source, and an electronic circuit controlling the supply of the power to the motor and the charge and discharge of the battery are required at a minimum. These are attached to proper places such as the main frame  1  or the front fork  2 , and the seat pipe  3  taking advantage of the object of the present invention, or may be housed in the hollow part when the frame has the hollow part. 
       Embodiment 8 
       [0067]    Embodiment 7 provided the motorized assistant bicycle. If the bicycle is driven only by the motorized force without assistance, it becomes a motorized bicycle. In this case, the pedals are not necessary. However, on the assumption that the battery has been discharged, it is advantageous for the pedals to be attached for emergency purposes. Meanwhile, if the bicycle exists because it is meant as a vehicle that is essentially moved by human power, Embodiment 8 should be rephrased as a motorized two-wheel vehicle, but the object of the present invention is not changed. 
       Embodiment 9 
       [0068]    A motorized assistant bicycle is given in Embodiment 7, and a motorized two-wheel vehicle was given in Embodiment 8. However, an internal-combustion engine may be used as a power source. In this case, it is convenient that an accelerator similar to that of an motorized two-wheel vehicle be added to a right-handed grip of the handle, and that the rotation of the engine be controlled. 
       Embodiment 10 
       [0069]    So far, the embodiment of the power assistant based on the electric motor or the internal-combustion engine has been provided. The present invention is configured so that the power device can be easily mounted, and be easily attached/detached. Thus, there is a fear of these external power devices being stolen. Accordingly, to prevent this, a mechanism such as a lock is installed so they are able to be attached/detached only by the owner or a person entrusted by him/her. 
       Embodiment 11 
       [0070]    So far, the present invention has been described using a case based on a chain used as a driving force transmission device. However, even in a case in which the shaft is driven using a rubber belt driving or bevel gears, the present invention can be carried out in a completely similar fashion. 
       INDUSTRIAL APPLICABILITY 
       [0071]    The integrally molded structural material based on the extruded material or the molded material, and the structure capable of meeting various purposes based on attaching/detaching of the components to/from the concave grooves formed in this structural material can be applied to various other instruments.