Patent Publication Number: US-2005121877-A1

Title: Bicycle frame

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
      This application is a continuation and claims the benefit of the filing date of Applicant&#39;s co-pending application Ser. No. 10/081,492, filed Feb. 22, 2002, which in turn is a based on and claims the filing date of provisional application Ser. No. 60/270,699, filed Feb. 22, 2001, both of which are incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      Not Applicable.  
     BACKGROUND OF THE INVENTION  
      The present invention relates to a bicycle frame incorporating an easily manufactured and easily replaceable shock absorber mechanism that provides increased torsional resistance.  
      Applicant&#39;s prior U.S. Pat. Nos. 4,792,150, 4,669,747, and 5,080,384, which are incorporated by reference, disclose a new type of bicycle frame incorporating a leaf spring connection between the top crossbar and seat tube (center post) of the frame, with a flexible cable connector extending between the head tube and lower end of the seat tube. The spring employed in U.S. Pat. Nos. 4,792,150 and 5,080,384 is a leaf spring comprising an elongated laminated fiberglass bar or plate having rounded edges that fit closely in oval openings in opposed fittings on the crossbar and seat tube. The springs are formed in multiple laminations of fiberglass reinforced resins. A substantial amount of work is required to shape the spring plates so that they fit closely in the fittings in the crossbar and seat tube. In addition, the spring plates have to be securely held in place by epoxy in order to maximize the rigidity of the frame. All of this requires a considerable amount of handwork and expense.  
      During operation over an extended period of time, all spring members eventually wear out. This is true of the fiberglass spring shown in the referenced patents. When this occurs, because of the complex construction of the springs and the extensive handwork required to remove and install new springs, springs generally are not replaced in the field. Instead, the frame must be returned to the factory for installation of new springs. This involves considerable expense to the bicycle owner and a considerable delay in the use of the bicycle.  
      An object of the present invention is to provide a suspension frame employing rod-shaped springs that provide increased torsional rigidity and yet are less expensive and are easily replaceable by the bicycle owner in the field. Other objectives of the present invention are to incorporate the new spring mechanism in a special collapsible or folding frame and to provide for wire management through a new wire management tube.  
     SUMMARY OF THE INVENTION  
      In one aspect of the present invention, a bicycle frame incorporates a folding mechanism that permits the front and rear portions of the bike to be folded together for easy portability of the bike. A spring release locking mechanism is employed to hold the frame in operating position until the frame is to be folded for transportation.  
      In another aspect of the present invention the front and rear portions of the frame are connected together by a flexible spring member that permits the front and rear portions of the frame to flex with respect to one another.  
      In the preferred embodiment, the bicycle seat mechanism is mounted at the rear of the front portion so that the spring cushions the seat from deflection forces received through the rear wheel.  
      In another embodiment of the present invention, the spring includes at least two laterally spaced, elongated rods extending between opposed mounting blocks in the front and rear portions of the frame, with the ends of the rods being held in the mounting blocks by a clamping means that can be released to permit removal and replacement of the spring members when desired. The clamping means can be positioned to lock the spring members in the mounting blocks.  
      Desirably, a pultruded cylindrical fiberglass rod spring ⅜-1 inch in diameter and preferably ⅝ inch in diameter is employed as the spring.  
      In another aspect of the present invention, a wire management tube is attached to the side of the crossbar of the bike and extends at least a portion of the length of the crossbar. Control wiring extends through the tube and is conveniently held in place by the tube. The tube is formed of an extruded plastic tubing having one generally flat side and an arcuate side, with a slot formed longitudinally in the tube. A strip of double-sided pressure sensitive adhesive tape is applied to the flat side of the tube. The wire management tube can thus be attached to the bicycle frame and removed and replaced when desired.  
      These and other features of the present invention are described in detail below and shown in the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       FIG. 1  is a side elevational view of a bicycle incorporating the bicycle frame of the present invention.  
       FIG. 2  is a fragmentary perspective view of the bicycle frame of  FIG. 1 , showing the spring assembly.  
       FIG. 3  is a fragmentary side elevational view of the spring assembly of the present invention.  
       FIG. 4  is a plan view of the spring assembly of  FIG. 3 .  
       FIG. 5  is a cross sectional view taken along lines  5 - 5  of  FIG. 4 .  
       FIG. 6  is a fragmentary side elevational view of the crossbar of the present invention and the wire management tube attached to the crossbar.  
       FIG. 7  is a cross sectional view taken along lines  7 - 7  of  FIG. 6 .  
       FIG. 8  is a side elevational view of a second embodiment of a frame of the present invention.  
       FIG. 9  is a fragmentary side elevational view of the frame of  FIG. 8 , showing of the spring assembly of the present invention.  
       FIG. 10  is a plan view of the spring assembly of  FIG. 9 .  
       FIG. 11  is an enlarged plan view of the spring assembly of  FIG. 10 .  
       FIG. 12  is a plan view of a steel mounting block for the spring elements shown in  FIGS. 1-10 .  
       FIG. 13  is an end elevational view of the spring mounting block of  FIG. 12 .  
       FIG. 14  is a side elevational view of the mounting block of  FIG. 12 .  
       FIG. 15  is a bottom plan view of the mounting block of  FIG. 12 .  
       FIG. 16  is a plan view of another embodiment of the spring mounting block of the present invention.  
       FIG. 17  is an end elevational view of the mounting block of  FIG. 16 .  
       FIG. 18  is a side elevational view of the mounting block of  FIG. 16 .  
       FIG. 19  is a side elevational view of a bicycle incorporating a folding bicycle frame of the present invention.  
       FIG. 20  is a side elevational view of the bicycle frame of  FIG. 19 , with the seat and handlebars removed.  
       FIG. 21  is a side elevational view of the bicycle frame of  FIG. 19 .  
       FIG. 22  is a side elevational view of the bicycle frame of  FIG. 21 , showing the frame folded into its folded position.  
       FIG. 23  is a plan view of a second embodiment of the spring assembly mechanism of the present invention.  
       FIG. 24  is a cross sectional view taken along lines  24 - 24  of  FIG. 23 .  
       FIG. 25  is plan view of the spring element of  FIG. 23 .  
       FIG. 26  is a plan view of a second spring element of  FIG. 23 .  
       FIG. 27  is an end view of the spring element of  FIG. 25 .  
       FIG. 28  is an end view of the spring element of  FIG. 26 .  
       FIG. 29  is a plan view of the pivot arm of the collapsible frame of  FIGS. 19-22 .  
       FIG. 30  is a side elevational view of the pivot arm of  FIG. 29 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to the drawings, a bicycle  10  incorporating the present invention is shown in  FIGS. 1-7 . Bicycle  10  includes frame  12  to which is mounted a seat assembly  14 , handlebar assembly  16 , front fork assembly  18 , pedal and crank assembly  20 , and front and rear wheels  22  and  24  respectively.  
      The frame includes a top tube or crossbar  26 , which has a head tube  28  mounted at a front end thereof. A seat tube  30  is mounted on an upwardly and rearwardly extending bracket  32  that is mounted at a rear end of crossbar  26 . A back or rear support triangle  34  comprises horizontal chain stay members  36 , a downtube  38 , and rearwardly extending seat stays  40 . Rear wheel  24  is attached to dropout fittings  42  at the rear end of back triangle  34 , while front wheel  22  is mounted on dropouts  44  at the lower ends of arms  46  of fork assembly  18 .  
      The front portion  47  of the frame comprises crossbar  26 , head tube  28  and seat tube  30 , all of which are rigidly mounted together. The front portion  47  of the frame is attached to the back triangle of the frame by means of the spring assembly  48  of the present invention and a tension cable assembly  45 , which includes a tension spring  51 . The cable can be released from the frame by removable pins at opposite ends (see  FIGS. 21 and 22  for details on the tension cable assembly).  
      Referring to  FIG. 4 , spring assembly  48  comprises a pair of opposed spring mounting blocks  60  and  62  attached to or formed in the rear end of the crossbar and an upper end of the down tube  38 , with two or more spaced spring elements  54  being mounted in the blocks and extending between the blocks to form a resilient spring connection between the back triangle and front portion of the frame.  
      Springs  54  are formed of fiberglass reinforced resin in the shape of elongated rods. These rods, which are available commercially, may be formed by pultrusion in the form of long rods and then cut to their desired lengths. The rods are desirably round in cross section, but they could be other shapes. Also, while two rods are shown in the drawings, a greater number of rods could be employed. The rods are about five-eighths to three-quarters inches in diameter, with a tolerance of one to two thousandths inches being preferred. For extra strength, the rods can be covered with a carbon fiber or Kevlar wrap, with the wrap being epoxied in place.  
      The advantage of the rods of the present invention is that they can be fabricated easily and relatively inexpensively when compared with the multiple laminar construction of the spring plates of the prior frames. Moreover, by providing spaced parallel rods instead of a flat plate, they are easier to mount, and they provide improved torsional rigidity without increasing the overall spring stiffness of the bike. Torsional rigidity is accomplished by separating the rods by an increased distance. This increased separation does not increase the total mass of spring, so the spring flex characteristics in a vertical direction can remain the same. With a leaf spring, in order to increase the torsional rigidity, the spring must be made wider. This increases the mass of the spring and thus the stiffness of the spring unless the spring is made thinner. If the spring is made thinner, then the spring is more fragile. With the present invention, relatively thick rods can be spaced a substantial distance apart, leaving open space between the rods, and this provides maximum torsional rigidity at the edges of the spring while still maintaining a desired spring flex characteristic. Also, the stress on the rods is shear stress, not torsion.  
      The spring of the present invention is desirably formed of a pultruded fiberglass rod. A diameter of ⅝ inches is desirable, and a diameter range of ⅜-1 inch is satisfactory. If more springs than two is employed, the diameter of the springs is reduced as necessary in order to retain desired flex characteristics.  
      The fiberglass springs of the present invention act both as springs and a shock absorber. However, an additional shock absorber  56  (shown in  FIG. 2 ) may be used in order to provide improved ride characteristics. Shock absorber  56  extends upwardly and forwardly from the down tube  38  to crossbar  26 .  
      The manner in which the rod springs are mounted in the frame is shown in  FIGS. 3-5 . Rear ends of rods  54  are mounted in a rear mounting block  60 , which is mounted at the top junction of seat stays  40  and down tube  38 . A front mounting block  62  is mounted at the rear end of cross bar  26 . Both mounting blocks include a pair of spaced openings  64  that are shaped to fit closely over rods  54 . Thus, when rods  54  are in a desired round shape, openings  64  also are round. An open slot  66  extends between openings  64 , thus leaving a compressible space between openings  64 . A locking bolt  68  extends through an opening  70  in an upper surface of the mounting block and threads into a threaded opening  72  in a lower surface of the mounting block. Rotation of the bolt by means of a hex wrench that fits into a hex shaped opening  74  in the head of the bolt causes the upper and lower portions  70  and  72  to be compressed together. This in turn causes the openings  64  to contract and compress around the periphery of rods  54  and thus provides an even compression gripping force around the periphery of the rods. Because of the compressibility of the openings in the mounting blocks, it is not necessary to permanently affix the rods in the mounting blocks by the use of epoxy or the like. Accordingly, to remove the rods, bolt  68  can be released and the rods can be easily pulled out of the mounting blocks. Thus, replacement of the springs in the field is easy and can be handled by the bicycle owner with conventional tools.  
      While the mounting block shown in  FIG. 5  is a one piece mounting block formed of steel or aluminum, the mounting block could be formed in two completely separate upper and lower sections with a space between the sections being provided so that the sections can clamp together on the mounting blocks. However, a one piece block with a compressible center section is desired because it provides a tighter and more uniform clamping force on the spring.  
      As shown in  FIG. 4 , front mounting block  62  is substantially the same in function as rear mounting block  60 . Front mounting block  62  may have a closed end  73  at the end opposite open end  76  and this mounting block may be formed of aluminum in order to be compatible with an aluminum crossbar. A closed end facilitates attachment to the crossbar, but is not required. A closed end serves to limit the distance that the spring rods may be inserted into the mounting block. Rear mounting block  60  can be formed of steel and may have an open rear end  78 . The ends  41  of seat stays  40  can be fitted and welded in the open end  78  of the mounting block. This provides a convenient and rigid mounting, while the ends of the seat stays limit the depth of insertion of the spring rods into the rear mounting block. A bolt  80  clamps the front ends of the rods in the front mounting block in the same manner as bolt  68  clamps the rear ends of the rods in mounting block  60 . Desirably, the rods are mounted in the mounting blocks so that the rods extend about one to one and one-eighth inches into each block and there is about one-eighth to one-quarter inch of exposed rod between the mounting blocks.  
      The use of a spring assembly wherein spaced fiberglass rods are clamped into opposed mounting blocks and can easily be released from the mounting blocks also makes it more convenient to transport the bike. The entire rear triangle of the bicycle can be removed from the rest of the frame for compact packaging simply by releasing the springs from one of the mounting blocks and separating the back triangle from the frame. A quick release fastener  90 , as shown in  FIG. 9 , can be used instead of one of the bolts  68  or  80  to facilitate disassembly of the frame.  
      Another feature of the invention is shown in  FIGS. 6 and 7 . A wire management tube  81  is attached to the side of crossbar  26  and extends at least a portion of the length of the crossbar. Wiring  84  extends through tube  81  and is conveniently held in a desired position by the tube. Tube  81  is formed of extruded plastic tubing having one generally flat side  86  and an arcuate side  88 , forming a generally round tube having one flat side. A slot  90  is formed longitudinally along the tube. Wiring  84  can be inserted longitudinally through the slot in the tube and the natural resilience of the plastic tubing and rib  93  on the edge of the slot urge the wiring to stay inside the tubing. A strip of double-sided, pressure sensitive adhesive tape  92  is applied to the flat side  86  of the tube. Thus, the tube can be applied to the bicycle frame at any convenient location, simply by removing the release paper applied to the pressure sensitive adhesive and then pressing the flat side of the tubing to the desired location. The ends of the tube are also attached to the crossbar by pop rivets  95  to make the attachment more secure. Similarly, if the tubing breaks or is damaged for any reason, the broken tubing can be removed and new tubing can be applied to the frame easily. The tubing is shown in one convenient location in the present invention, but it should be understood that this tubing could be applied anywhere where it is desired. The slotted tubing assembly is commercially available and thus is relatively inexpensive.  
      The frame of  FIG. 1  is different from the frames in applicant&#39;s above-cited prior patents in some important aspects. In the present invention, the seat tube and seat are mounted on the crossbar in front of spring assembly  48 , with the spring being positioned between the rear wheel and the seat mechanism. In the prior patents, the seat was in effect rigidly connected with the support frame for the rear wheel, and the spring was positioned between the seat mechanism and the front portion of the frame. By having the seat connected to the front portion of the frame, an improved ride is provided.  
      While the improved frame construction shown in  FIG. 1  is desired, the spring mechanism of the present invention can also be employed in a more conventional frame  100 , as shown in  FIG. 8 . Frame  100  comprises crossbar  102 , seat tube  104 , chainstays  106 , and seatstays  108 . Spring mechanism  110  interconnects the rear end of crossbar  102  with a fitting  112  at the junction of seatstays  108  and seat tube  104 . As shown in  FIGS. 9 and 10 , the construction of the spring mechanism is substantially the same as in the prior embodiment, with a quick release fastener  90  being employed for easy disassembly of the bike for transportation or storage.  
      A more detailed illustration of the spring blocks employed in the present invention is shown in  FIGS. 12-18 . The spring block  99  of  FIG. 12  can be a steel block that is typically attached to the rear triangle. Block  99  comprises parallel upper and lower surfaces  101  and  103 , and rounded side edges  104 . Openings  105  for the springs are spaced apart in the block and separated by an interconnecting slot  107 . A vertical opening  109  through the block can be threaded at a lower portion  111 . A locking bolt (which can include a quick release fitting) can be threaded into the block (or extended all the way through the opening in the block to a nut on the opposite side of the block) in order to compress the upper and lower surfaces together so as to grip tightly the fiberglass rod springs in their openings. The rounded sidewalls of the mounting block cause the mounting block to deflect or bend uniformly around the springs so as to grip the springs evenly when the center portion of the mounting block is compressed with the bolt.  
      An aluminum mounting block  113  formed of 6061 aluminum (preferably annealed T-0) is shown in  FIGS. 16-18 . This block is substantially rectangular with rounded corners and includes a pair of spaced openings  115  interconnected by a slot  117 . A closed back  119  closes the rear end of the block. An opening  121 , which can have a threaded lower end  123 , extends vertically through the block. The remaining features of this block are substantially the same as the other block. The rounded block configuration of  FIG. 13  is preferred to the more rectangular configuration of  FIG. 17  because the rounded sidewalls adjacent the rod spring openings facilitate a better gripping force on the rod springs when the locking bolt is tightened.  
      Another embodiment of a bicycle  120  incorporating the features of the present invention is shown in  FIGS. 19-22 . Bicycle  120  is a folding bicycle and comprises a frame  122  that is similar to the frame  12  of the bicycle shown in  FIG. 1 . Frame  122  includes a crossbar  124 , an upwardly and rearwardly extending mounting bracket  126  at the rear end thereof, and a seat tube  128  attached to bracket  126 . A seat mounted on a seat stem fits on the seat tube. A head tube  130  is mounted on the front end of crossbar  124 . Handlebars  132  are mounted in the head tube by means of a steerer stem  134  that fits inside of head tube  130 . A fork  136  is mounted at the lower end of head tube  130 , and wheel  138  is mounted in the fork. A rear wheel  140  is mounted on a back triangle  142 , which comprises chainstays  144 , seatstays  146 , and a downtube  148 . All of this is substantially the same as the first embodiment described above. The distinction in this embodiment of the invention is that the back triangle is connected to the front portion of the frame by means of a swivel mechanism  150 . Swivel mechanism  150  comprises an elongated pivot arm  152  ( FIGS. 29 and 30 ) that has a mounting block  154  for the rod spring mechanism  155  at a rear end. The pivot arm has a vertical opening  157  therethrough that is pivotally mounted on a pivot shaft  156  that extends downwardly from a rear portion of crossbar  124 . A quick release locking mechanism  158  extending between spaced flanges  159  can be tightened and released in order to clamp arm  152  in a fixed operating position on pivot shaft  156 , where the arm extends rearwardly in line with the crossbar, as shown in  FIGS. 19 and 21 . A spring mounted locking pin  161  can be used to securely lock the pivot arm in operation position. Pin  161  fits in crossbar opening  163  to releasingly lock the back triangle in its operating position. The pin can be released by pulling down on stem  165  in order to collapse the frame to the position shown in  FIG. 22   
      As shown in  FIG. 22 , when the locking mechanism is released, the back triangle of the frame can be pivoted forwardly so that it is positioned under the crossbar, for purposes of transportation or storage of the bike or bike frame.  
      The spring mechanism  155  of the folding bicycle can be the same as the spring mechanism for the non-folding bicycle described above. Alternatively, a modified spring mechanism, disclosed in detail in  FIGS. 23-28 , can be employed. In this embodiment, front and rear mounting blocks  154  and  170 , shown in  FIG. 23 , can be constructed substantially similar to the mounting blocks described above (preferably similar to block  99 ), with the exception that, instead of a single vertical opening through each mounting block, there are two spaced openings  174  and  176 , each of which can have a threaded portion  175  and  177  in the lower side of the mounting block in order to receive a locking bolt. Openings  174  and  176  are oriented so that they partially intersect openings  178  and  180  that extend through the mounting block for the fiberglass rod springs. Fiberglass rods  182  and  184  (which can be identical) are mounted in openings  178  and  180 . Fiberglass rods  182  and  184  are the same as the fiberglass rods disclosed above for the other embodiments, with the exception that the rods have arcuate cutaway portions  188  and  190 . These mate with openings  174  and  176 . Thus, when locking bolts are fitted through openings  174  and  176  with the springs in place, the bolts fit through cutaway portions  188  and  190  and then are tightened in the mounting block. The arcuate openings  188  and  190  in the spring rod cause the spring rod to be locked in one particular axial position in the mounting block as long as the bolt is in place. Thus, the bolts in the mounting block serve both as a safety lock to prevent the bicycle frame from falling apart if a bolt is loose and they also serve as locators to properly locate the axial position of the fiberglass rod within the mounting block. By using the bolts as locators and a safety lock, a desired spacing between the two mounting blocks can be achieved for maximum spring effectiveness, and the bolts prevent the occurrence of an accident due to a rod spring being released from its mounting block.  
      The cable  49  interconnecting the back triangle and the head tube or front of the crossbar is the same as other embodiments. This cable can include releasable pins  118  and  125  at opposite ends that permit the cable to be released for removal or adjustment if desired. The cable is attached to a collar  131  mounted on the down tube  148  at the rear end. Collar  131  can rotate around down tube  148 . A clamp  133  clamps on the down tube above collar  131  to prevent upward axial movement of collar  131 . In the illustrated embodiment, it is not essential that collar  131  be rotatable around the down tube, so collar  131  and clamp  133  could be combined. The cable does not have to be released for folding, however. The front end of the cable is attached to the crossbar by means of a spring connector  51 . The spring connector includes a pressure plate  200  attached by ears  202  to the crossbar by pin  125 . A coil spring  204  is positioned between the ears. A rod on the end of the cable extends through the spring and through another pressure plate  206  to a threaded end  208 . A locknut  210  fits on the threaded end and bears against the end of pressure plate  206  so that when tension is exerted on the cable, the spring is compressed. The cable provides a flexible tension connection that complements the action of the rod spring mechanism.  
      It should be understood that the foregoing is merely exemplary of the preferred practice of the present invention and that various changes and modifications may be made in the arrangements and details of construction without departing from the spirit and scope of the present invention.