Abstract:
An aerobar assembly is arranged to be mounted on the handlebar stem, rather than on the handlebars, of a bicycle. The aerobar assembly in turn supports the handlebars. By mounting the aerobar on the stem, the range of adjustability of the aerobar is greatly increased, and the handlebar is subject to less torsional forces. The aerobar assembly includes a pillar stem having one end secured to the stem and a support structure at a second end for mounting an aerobar bracket, an arm rest support, and handlebar clamps. The aerobar bracket is arranged to permit axial adjustment of aerobar position, while the arm rest support is arranged to enable lateral, horizontal pivoting, vertical swivelling, and fore-aft adjustment of arm rest position independent of aerobar position. The handlebar mount preferably uses C-clamps that can easily be substituted to accommodate different handlebar configurations.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an aerodynamic handlebar extension for bicycles, also known as an “aero bar” or aerobar, and in particular to an aerobar assembly that mounts on the handlebar stem that is part of the fork of the bicycle, rather than on the existing handlebars, and that thereby provides improved adjustability, comfort, and safety. 
   2. Description of Related Art 
   The concept of handlebar extensions that permit the rider of a bicycle to assume an improved aerodynamic position, by positioning the riders hands forwardly of the handlebar and by providing support for the riders elbows or forearms, is well-known. Conceived in the mid-1980&#39;s, the aerobar was quickly adopted by triathletes. Since Greg LeMond used them in winning the 1989 Tour de France, aerobars have also attained widespread use by bicycle racers, particularly during time trials. 
   In competitive cycling, proper fitting or adjustment of the aerobar to the rider is critical to achieving optimal performance. In general, the closer the torso of the rider is to horizontal, the lower the aerodynamic drag on the rider. However, the resulting extension of the lower back and hamstrings in the optimal aerodynamic position may cause injury or discomfort to the rider, and may prevent the rider from achieving maximum power. In addition, proper positioning is necessary to ensure clearance for the rider&#39;s knees. As a result, the optimal position for racing or triathlons depends on the physiology of the rider, and can vary substantially from rider to rider. 
   Most currently available aerobars are either nonadjustable or have at best a limited adjustability. While the aerobars of an adjustable aerobar assembly can usually be moved in a fore-to-aft direction to ensure proper horizontal positioning of the rider and accommodate different arm lengths, the elbow rests or pads can only be adjusted laterally, and fail to take into account skew or angling of the rider&#39;s arm, either in a horizontal or vertical plane. Furthermore, because the conventional aerobars are either integral with the handlebars or clamped thereto, possibilities for adjustment are limited by the position and configuration of the handlebars. 
   On the other hand, many conventional aerobar brackets offer too great a lateral tolerance for the aerobars, because the left and right aerobar brackets are mounted independently on the handlebars. This makes it difficult to position the aerobars symmetrically, in a balanced manner, on the left and right sides of the stem. 
   Another problem with conventional aerobars is the problem of compatibility. Most conventional aerobars are suitable only for a single type of handlebars. Different types of handlebars, e.g., drop bars or bullhorn style TT bars, require different aerobar designs to ensure proper positioning and clamping of the aerobar, provide access to shift levers if stem mounted, and to ensure clearance between the aerobar mount and the knees of the rider. 
   In addition to the problems of limited adjustability and compatibility, another problem with conventional aerobars is that they can present a significant safety hazard. The cinch clamps conventionally used to secure an aerobar to the handlebars of a bicycle exert a substantial amount of force on the handlebar, in order to counter the rotational torque exerted when the rider leans on the aerobars. This anti-torsion clamping force, combined with vibrations and road shocks, can cause metal fatigue and cracking of the handlebars, while vibrations and shocks also can cause the bolts that secure the clamp to the handlebars to loosen and permit the aerobars so suddenly become loose or fall off. 
   Furthermore, because the conventional aerobar handlebar brackets must be positioned so that the brackets and aerobars clear the stem, they enable the aerobars to be slid to a position where they extend behind the fork, in the path of the rider&#39;s knees. This can also present a serious safety hazard. 
   SUMMARY OF THE INVENTION 
   It is accordingly a first objective of the invention to overcome the drawbacks of the prior art by providing an aerobar having enhanced performance, comfort, safety, and reliability. 
   It is a second objective of the invention to provide an aerobar that is fully adjustable to enable a rider to assume a position that provides optimal performance during speed racing, and that also provides an optimal balance of speed and comfort during triathlons and other endurance contests. 
   It is a third objective of the invention to provide an aerobar that is simple in construction and easily mounted on a bicycle. 
   It is a fourth objective of the invention to provide an aerobar that provides increased safety by eliminating the problems caused by the conventional use of cinch clamps to secure conventional aerobars to handlebars, including cracking of the handlebars and loosening bolts. 
   It is a fifth objective of the invention to provide an aerobar that can be adapted to any handlebar style, including those in which the handlebars have a non-circular cross-section. 
   These objectives are achieved, in accordance with the principles of a preferred embodiment of the invention, by providing an aerobar system that is arranged to be mounted on the handlebar stem of the bicycle fork, rather than on the handlebars, and that in turn supports the handlebars. 
   According to an especially preferred embodiment of the invention, the handlebars, aerobars, and arm rests are separately mounted to a pillar stem clamped to the handlebar stem by cap screws that thread directly into the pillar stem without the use of bolts. The bracket/support structures for the aerobars and arms rests permit a variety of independent adjustments of aerobar and arm rest position, including fore-to-aft adjustment of aerobar position, lateral and fore-to-aft adjustment of arm rest position, and adjustment of arm rest angle or skew in both horizontal and vertical planes. The handlebar mount preferably uses C-clamps that can easily be substituted to accommodate different handle bar configurations. 
   By mounting the aerobar on the stem, the range and ease of adjustability of the aerobars or arm rests may be greatly increased, while still ensuring that the aerobars will be laterally centered and positioned away from the riders knees. In addition, mounting of the aerobars on the handlebar stem of the bicycle fork rather than the handlebars provide a mechanical advantage that prevents torsional forces from cracking the handlebars, while the use of socket or cap screws threaded into a pillar stem to support the arm rests, aerobars, and handlebars eliminate the problem of bolt loosening. 
   Finally, by providing an independent modular support for the aerobars, it is possible to achieve an optimal stem length for positioning the handlebars, without or without the addition of aerobars and arm rests. The pillar stem can initially provided solely as a handlebar support, with the aerobars and arm rests offered as an option which can easily be installed, removed, replaced, and/or adjusted at a later time simply by loosening and tightening one or two screws, without such inconveniences as having to remove or re-apply handlebar tape. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is an isometric view of an aerobar assembly constructed in accordance with the principles of a preferred embodiment of the invention. 
       FIG. 1B  is a side view of the aerobar assembly of  FIG. 1 . 
       FIG. 2  is an exploded isometric view of a pillar stem for use in the aerobar assembly of  FIG. 1 . 
       FIG. 3A  is an exploded isometric view of an aerobar bracket sub-assembly for use in the aerobar assembly of  FIG. 1 . 
       FIG. 3B  is a front view of the aerobar bracket sub-assembly of  FIG. 3A . 
       FIG. 3C  is a top view of the aerobar bracket sub-assembly of  FIG. 3A , with a modified aerobar configuration. 
       FIG. 4  is an isometric view of an arm rest sub-assembly for use in the aerobar assembly of  FIG. 1 . 
       FIG. 5A  is an exploded isometric view of the arm rest sub-assembly of  FIG. 4 . 
       FIG. 5B  is a front view of the arm rest sub-assembly of  FIG. 4  after installation of the handlebars. 
       FIG. 6  is a cross-sectional front view of the arm rest sub-assembly of  FIG. 4 , showing lateral adjustment of the arm rests. 
       FIG. 7  is a side view of the arm rest sub-assembly of  FIG. 4 , showing pivotal adjustment of an arm rest about the axis of the arm rest support. 
       FIG. 8  is an isometric view of a handlebar that may be used with the aerobar assembly of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1A  is an isometric view of an aerobar assembly according to a preferred embodiment of the invention, and  FIG. 1B  is a side view. Various sub-assemblies of the aerobar assembly illustrated in  FIGS. 1A and 1B  are shown in  FIGS. 2–8 .  FIG. 2  illustrates a pillar stem mount  20  and associated hardware for mounting the aerobar assembly on the handlebar stem of a bicycle, and for securing a handlebar  12  to the aerobar assembly, while  FIGS. 3A–3C  show a pair of aerobars  32  and a bracket  30  for adjustably mounting the aerobars on the pillar stem mount,  FIGS. 4 ,  5 A,  5 B,  6 , and  7  illustrate the structure and operation of an arm rest sub-assembly  40 , and  FIG. 8  shows one of many handlebar configurations that may be mounted to the aerobar assembly of  FIG. 1 . 
   As illustrated in  FIGS. 1A ,  1 B, and  2 , the pillar stem mount  20  is arranged to be mounted on the handlebar stem  18  of a bicycle fork by means of a cinch clamp  21 . Because the handlebar stem of the bicycle fork typically has a larger diameter than the handlebars, it is better able to withstand clamping, and therefore provides a more secure mount for the aerobar assembly. Furthermore, the handlebar stem is subjected by the pillar stem to a linear, downwardly directed force that is absorbed by the frame rather than to a torsional force borne by the handlebars, eliminating the problem of metal fatigue and cracking of the handlebars. 
   It will be appreciated that cinch clamp  21  may be replaced by other types of structures for securing the pillar stem mount to the stem  18  of a bicycle, or the pillar stem  20  may even be made integral with the stem  18 , without departing from the scope of the invention. Although not shown, the cinch clamp is typically tightened by screws or bolts extending through openings in the clamp in conventional fashion, and the clamp may rest on the frame into which the pillar stem is inserted. 
   The main body of the pillar stem is cylindrical and may be hollow or solid, although a hollow configuration is preferred in order to reduce the weight of the assembly. At the opposite end of pillar stem  20  from the cinch clamp  21  is an integral, generally c-shaped supporting structure  22  which has three functions: (i) to support the handlebars; (ii) to support the aerobar bracket; and (iii) to support the arm rest. The pillar stem including the supporting structure  22  at one end are preferably cast or machined as a single piece or member. Each of the handlebars, the aerobar bracket, and the arm rest assembly is independently mounted on the c-shaped supporting structure  22 , and therefore independently adjustable. 
   The supporting structure is illustrated as including a lower pair of threaded openings  225  for mounting the aerobar bracket, an upper pair of threaded openings  224  for mounting the arm rest sub-assembly, and two pairs of frontwardly facing threaded openings  223  for mounting handlebar C-clamps or brackets  23 . 
   Preferably, each sub-assembly is mounted using cap screws or machine screws. The illustrated screws are hex type socket head cap screws, although other types of screws or fasteners may be utilized so long as the screws or other fasteners mount the respective subassemblies to the supporting structure  22  in a secure manner and, where appropriate, in such a way that the mountings can be loosened and the positions of the subassemblies adjusted. 
   As illustrated in  FIGS. 3A–3C , the aerobar bracket  31  preferably includes a pair of openings  311  for receiving aerobars  33  and a central connecting portion in which are located upper and lower pairs of through-holes  312 , either or both pairs of which may be threaded or smooth. 
   Upon insertion of the aerobars to a desired position in the openings  311 , the screws  313 , which have been extended through openings  312  and threaded into openings  225  in the supporting structure of pillar stem  20  just far enough to avoid stressing the bracket  31 , are tightened to cause the bracket to securely clamp and center the aerobars in the openings  311  by causing the lower connecting portion between the openings to be pulled toward the upper opening. To adjust the forward extent of the aerobars  32 , screws  313  are simply loosed to a point at which the lower connecting portions is sufficiently far from the upper connecting portion to enable release of the aerobars for movement within the openings  32 , after which the screws are tightened to the support  22  of pillar stem  21  to again clamp the aerobars. 
   Preferably, the bracket positions the aerobars in front of the fork, so that the fork prevents a user from extending the aerobars rearwardly to a position where the rider&#39;s knees could come into contact with the aerobars. However, those skilled in the art will appreciate that the invention is not limited to a particular aerobar configuration. For example, alternative aerobar styles are illustrated in  FIGS. 3A ,  3 B, and  3 C, the latter having a dual-curved configuration. The invention is intended to be used with any aerobar shape, length, and position. 
   The arm rest sub-assembly is illustrated in  FIGS. 4 ,  5 A,  5 B,  6 , and  7 . Each of the arm plates  42  is adjustably mounted on an elongated, generally tubular or cylindrical arm plate support  41 , which is mounted on the top of the pillar stem support structure  22  by two screws  413  arranged to extend through openings  412  in the support  41  and threaded openings  224  at the top of support structure  22 . 
   Preferably, support  41  includes some sort of alignment structure arranged to fit into a complementary alignment structure in the support structure  22 . For example, arm rest support  41  is illustrated as including notches or depressions  411  arranged to fit over complementary ridges or projections in the top of the support structure  22  at the end of the pillar stem  21 , thereby facilitating lateral alignment of the support  41  and the support structure  22 . 
   Arm rest support  41  includes two hollow sections in which are fitted two cylindrical, transversely-threaded dual-head nuts  415  arranged to slide axially within the support. Each of the threaded openings in each of nuts  415  is arranged to receive a cap screw  41  via slots  414  in support  41  and beveled washers  418 . In addition, the cap screws received by nuts  415  respectively extend through openings  422  and  423  in the arm rest plates  42 , with one of the pairs of cap screws for each nut extending through opening  422  and the other through opening  423 . Openings  422  are circular while openings  423  are curved slots for reasons that will be discussed below in connection with  FIG. 7 . 
   The nuts  415  are secured within the support  41  by threaded end caps  416 , which may of course take a variety of forms, including press fit rather than threaded caps. 
   Those skilled in the art will appreciate that nuts  415  are not limited to a dual-head shape, but may be in the form of a single cylinder with two threaded holes, or other shapes to accommodate different arm rest support configurations, including flanges or grooves to facilitate alignment of the threaded openings with the slot  414 . 
   In addition, washers  418 , which have a curved lower surface corresponding in shape to the curved surface of support  41  and a counter sink at the top to receive the heads of screws  421 , may have a variety of shapes to accommodate different arm rest support and screw head shapes. 
   When the cap screws are extended through the respective openings in arm rest plates  42 , washers  418 , and slots  414 , they may be threaded into openings  417  to fixedly secure the arm rest plates  42  to the support  414 . However, as illustrated in  FIG. 6 , because slots  414  are longer than the distance between openings  417  in each cylindrical nut  415 , as illustrated in  FIG. 6 , when the cap screws are loosed to permit relative movement between the nut and the support  411 , but not sufficiently to separate the cap screws from the openings, the arm rest plates  42  may be slid in a direction parallel to slots  414 , and thereby laterally adjusted relative to the support. 
   In addition, as illustrated in  FIG. 7 , because the slots  411  are wide enough to permit movement of the cap screws across the width of the slots, i.e., in a tangential direction relative to support  411 , and because of the curved lower surface of washers  418 , when the cap screws are loosened in the manner described above, the arm rest assemblies can be swivelled or pivoted around the axis of the support so that they tilt upwardly or downwardly, or are horizontal, in accordance with the preference of the rider. 
   Finally, the skew or angle of the arm rest plate  42  in the horizontal plane, i.e., relative to a substantially vertical pivot, may also be adjusted, upon loosening of the cap screws by an amount sufficient to permit movement between the arm rest plates and support  411  without separating the screws from the threaded openings  417  in nuts  415 , by pivoting the arm rest plates around the respective cap screws extending through openings  422 , which by their circular nature providing a pivot point. Slots  423  have a curvature that forms a constant radius with the center of openings  422 , and thus the slots are capable of sliding relative to the cap screws extending therethrough, allowing the entire arm plate to pivot. 
   As illustrated, arm rest plates include two circular openings  422  in each arm rest  42 , and two slotted openings  423 . This permits the fore-to-aft position of the arm rests relative to the support  411  to be adjusted by selectively using either the forwardmost or rearward most one of the slots  422  and  423  as the slots through which cap screws  421  and  422  are extended. This is an optional feature, and it is within the scope of the invention to use a single opening  422  and a single opening  423  in each arm rest plate, or more than two of each type of opening to achieve finer adjustment. 
   Additional optional features of the arm rest include slots  424  which reduce the weight of the plates and/or provide ventilation. The arm rest plates may be padded (not shown) for further comfort, coated with rubber, plastic, or the like, or even made of a synthetic rather than metal material. Other parts of the aerobar assembly may also be made of metal or other materials, the materials of the various parts forming no part of the present invention. 
   The final sub-assembly of the aerobar assembly illustrated in  FIG. 1  is the handlebar sub-assembly, which consists of a handlebar  10 , such as the one illustrated in  FIG. 8 , and C-clamps or brackets  23 . The brackets each include openings  231  for cap screws  232 , which are extended through the openings  231  and threaded into openings  223  to secure the handlebar to the pillar stem mount. 
   This arrangement permits a variety of different handlebar configurations to be used with the aerobar assembly of the invention. For example, the handlebar may correspond to handlebar  10  illustrated in  FIG. 8 , which is a drop style handlebar having downwardly and inwardly curved drop extensions  12  and an oval base bar  11 , i.e., a base bar with an oval cross-section. Numerous other cross-sectional base bar shapes can be accommodated by the illustrated C-clamps, and if a different cross-sectional shape that does not fit the illustrated C-clamps, the C-clamps can be replaced by other clamp configurations, or by a suitably shaped or configured bracket. 
   Having thus described a preferred embodiment of the invention in sufficient detail to enable those skilled in the art to make and use the invention, it will be appreciated that numerous variations of the illustrated embodiment may be made without departing from the scope of the invention, such as use of different types of screws or fasteners, different arm plate configurations, different clamp configurations for the stem mount and the handlebar mount, and so forth. It is accordingly intended that the invention not be limited to the embodiment illustrated in the drawings or accompanying description, but rather that it be defined solely in accordance with the appended claims.