BACKGROUND OF THE INVENTION In recent decades, popularity of folding bicycles has grown significantly as populations increase in density and in reliance on public transportation. Public transportation often fails to deliver commuters precisely to their respective destinations. Accordingly, most people using public transportation must resort to walking for a relatively small, yet significant, distance. Bicycles tend to be unsatisfactory adjuncts to public transportation since bicycles are relatively large and bulky items which cannot be easily carried on public transportation such as busses and trains.

One substantially successful transportation mechanism for bridging the gaps in public transportation for individual commuters is the folding bicycle. Currently available folding bicycles can fold to sizes smaller than a typical small suitcase and yet ride nearly as easily as a regular bicycle. To achieve such small sizes, folding bicycles typically involve intricate and complex mechanical solutions. One area in which substantial attention in devoted is that of the handlebar.

Most folding bicycles either use a folding handlebar stem or require that the front wheel and tire be removed for complete folding. Removing the front wheel of a bicycle can be awkward, especially for a commuter, since the removed wheel is a detached piece of equipment that must either (a) somehow be attached to the rest of the folded bicycle or (b) be carried separately. Designing the handlebar to be foldable introduces weakness and perhaps unwanted play and movement in a critical structural part of a bicycle.

Folding handlebars date back to the early history of the bicycle and yet tend not to be used in folding bicycles. Early attempts at folding handlebars were to allow for adjustable riding positions. Examples include folding handlebars described by U. S. Patent 864,202 to Simmons (Aug. 27,1907); U. S. Patent 3,863,521 to Gatsos et al. (Feb. 4,1975) ; and U. S.

Patent 5,737,967 to Hartley (Apr. 14,1998). These folding handlebars focus on adjustability while riding and provide little, if any, reduction in size.

On the other hand, folding handlebars which are designed to reduce the size of a bicycle or other vehicle for storage and/or carrying typically rely on mechanisms external to the handlebars and/or introduce weakness and movement in a critical structural component of the vehicle. Mechanisms external to the handlebars (e. g., U. S. Patent 4,634,138 to Fryer et al.-Jan. 6,1987) such as external spring latch handles pose risks for snagging clothing while riding.

More important, however, is the introduction of weakness and movement into a critical structural component of a bicycle. The handlebar of a bicycle bears heavy loads. In particular, more aggressive contemporary riding styles, e. g., in urban and off-road riding, places a rider's weight more forward with substantial weight over the handlebar. In addition, any bumps or shocks at the front wheel are typically translated directly to the handlebar.

While other front-end components are positioned to handle substantial vertical loads of shocks and bumps to the front tire, handlebars literally stand out as the component to handle such loads transversely. Accordingly, the handlebar is a structurally critical component of a bicycle and must handle transverse loading.

Most conventional folding handlebars introduce a folding mechanism which allows for folding in precisely the transverse direction in which loads are borne. One example is described in British Patent No. 7578 (1891) to Parkes et al. in which handlebars slide out of a tube to expose a joint about which the handlebars fold. In sliding in and out of a tube, the handlebars require a clearance, however small, to allow for such sliding. Such a clearance, however small, introduces play in the handlebars such that the handlebars are capable of movement independent of the remainder of the bicycle and independent of the sliding motion required to fold the handlebars. In particular, such introduces play transverse to the handlebars. Such play, during rugged riding, can cause excessive wear in the handlebars, can cause weakness in the handlebars, and can be annoying to the rider.

Folding handlebars in general have not enjoyed much commercial success. Such is not due to lack of interest in the marketplace. To the contrary, hundreds of thousands of automobile-mounted bicycle racks are sold to overcome the disadvantage of rigid, non-folding handlebars, namely, that bicycles with such handlebars do not generally fit in the typical automobile trunk. In particular, handlebars protrude from the generally slender shape of most bicycles and literally stand out as the most difficult component to stow for storage or transportation. For example, quick-release front hubs allow the front wheel of many full-size bicycles to be quickly and easily removed. However, the handlebars continue to protrude as the nemesis of many a cyclist trying to fit a full-size bicycle with the front wheel removed into the trunk of a typical automobile. Similarly, protruding handlebars require considerable storage space, e. g., in the garage of the cyclist. The reason for lack of commercial success for folding handlebars is the failure of prior art handlebars to overcome such disadvantages as excess weight, excess complexity, protruding parts, and insufficient transverse strength and rigidity.

What is needed is a folding handlebar, e. g., one suitable for use on a bicycle, which allows virtually no play transverse to the handlebar and which handles transverse loading virtually as well as a conventional, non-folding handlebar.

SUMMARY OF THE INVENTION In accordance with the present invention, tapered proximal ends of grip ends fit tightly into tapered sockets of a center portion of a folding handlebar such that, in a locked riding position, the handlebar resists any noticeable play or movement transverse to the length of the handlebar. Such provides unusual strength and rigidity in the folding handlebar that rivals fixed, non-folding handlebars. Yet, simultaneously, the tapered fit between the grip ends and the tapered sockets of the center portion of the folding handlebar allows relatively easy extraction along the length of the grip ends from the center portion to expose a hinge about which each grip end folds.

Substantially all strength in the folding handlebar according to the present invention comes from the tapered, tight fit between the grip ends and the tapered sockets of the center portion. Accordingly, no external, protruding parts are needed to hold the grip ends in the locked riding position. A small, internal retention pin and an internal retention spring are all that is needed to prevent inadvertent extraction of the grip ends during riding. As a result, the folding handlebars according to the present invention achieve unsurpassed strength transverse to its length while minimizing overall weight and having a clean exterior such that clothes and other articles do not snag any protruding parts of the handlebar.

Another advantage realized in accordance with the present invention is simplicity in the design of the folding handlebar. Since the majority of the transverse strength and rigidity is provided by the tapered tight fit between the grip ends and the center portion, a simple, relatively light force is exerted along the length of the grip end to easily extract the grip end from the tapered socket of the center portion to expose a hinge pin about which the grip end folds. Such enables one-handed extraction and folding of a grip end by a rider.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a folding handlebar in accordance with the present invention showing one grip end in a folded position and another grip end in a locked riding position.

Figure 2 is a more detailed cross-sectional view of a grip end and tapered socket assembly of the folding handlebar of Figure 1.

Figure 3 is a perspective view of the tapered socket of Figure 2.

Figure 4 is a plan view of the tapered socket of Figures 2 and 3.

Figure 5 is a cross-sectional view of the tapered socket of Figure 4 taken along line 5-5.

Figure 6 is a plan view of the grip end of Figures 1 and 2.

Figure 7 is a cross-sectional view of the grip end of Figure 6 taken along line 7-7.

DETAILED DESCRIPTION In accordance with the present invention, a taper 204 (Figure 2) of a grip end 104R of a folding handlebar 100 (Figure 1) fits into a tapered socket 202 (Figure 2) to provide a very tight fit at tapered contact region 206. Tapered contact 206 provides virtually no clearance between taper 204 and tapered socket 202 and therefore provides virtually no play transverse to grip end 104R. In addition, tapered contact region 206 provides considerable strength transverse to grip end 104R (e. g., in the direction of arrow T), generally as strong as non- folding handlebars. Simultaneously, tapered contact region 206 allows easy movement of grip end 104R along the length of grip end 104R, i. e., in the direction of arrow A, and therefore allows easy folding of grip end 104R.

Handlebar 100 (Figure 1) includes a center portion 102 and left and right end grips 104L and 104R, respectively. End grip 104L is shown in a folded position. End grip 104R is shown in a locked, riding position. End grips 104L and 104R are directly analogous to one another, and any description of one herein is equally applicable to the other.

End grip 104R is pivotably attached to a retention member 208 (Figure 2) by a hinge pin 212. A spring 210 between retention member 208 and tapered socket 202 applies a continuous force opposite arrow A to grip end 104R and resists inadvertent extraction of grip end 104R along the direction of arrow A. It should be noted that the particularly tight fit along tapered contact region 206 between taper 204 and tapered socket 202 provides sufficient friction to resist the relatively light loads along arrow A during riding and to hold grip end 104R in the locked, riding position while riding, even without the assistance of spring 210.

A more significant role of spring 210 is to keep grip end 104R attached to handlebar 100 while in the folded position (as shown for grip end 104L) so as to avoid misplacement and/or loss of grip end 104R by the rider.

Inadvertent extraction of grip end 104R along arrow A is also prevented by a retention pin 214. Retention pin 214 extends into a retention hole 220 in tapered socket 202, locking grip end 104R into tapered socket 202. Retention pin 214 is pushed into retention hole 220 by a spring 218 between retention pin 214 and a plug 216. In one embodiment, plug 216 is a screw.

Tapered socket 202 is shown in a perspective view in Figure 3. Tapered socket 202 includes a notch 3 02 into which plug 214 (Figure 2) fits when grip end 104R is in the locked, riding position. Such resists twisting of end grip 104R relative to center portion 102 (Figure 1) during riding-preserving relative rotational orientation of brake and shifting levers which can be attached to handlebar 100-and assists in alignment of retention pin 214 (Figure 2) with retention hole 220 during insertion of taper 204 into tapered socket 202. Tapered socket 202 (Figure 3) also includes a center portion 3 04 which is press-fit securely into center portion 102 as shown in Figure 2. Outer portion 306 (Figure 3) of tapered socket 202 forms a flange which butts against center portion 102 as shown in Figure 2. In addition, an annular notch 308 (Figure 3) forms a seat for spring 210 (Figure 2). Tapered socket 202 is shown in plan view in Figure 4. In this illustrative embodiment, retention hole 220 has a diameter of 6.0 mm.

Tapered socket 202 includes a tapered recess 502 into which grip end 104R is accepted. In this illustrative embodiment, tapered recess 502 is conical in shape with a radius angle 504 of 3' (a diameter angle 506 of 6°) and a conical height 508 of 173.77 mm measured from a conical apex 512. While tapered recess 502 is shown to be conical, it is appreciated that other tapered shapes can be used. Such other shapes include, for example, conical shapes in which the base is non-circular (e. g., elliptical) and pyramid shapes in which the base is square, triangular, pentagonal, or generally any polygon shape. In addition, while tapered recess 502 is shown to have a cross-sectional diameter which decreases linearly along its length, it is appreciated that tapers which decrease in cross-sectional dimensions non-linearly along the length of tapered recess 502 can be used. At its outer edge 510, tapered socket 202 is beveled to facilitate insertion of grip end 104R (Figure 2).

Grip end 104R is shown in plan view in Figure 6. Grip end 104R has a grip portion 602 which is generally cylindrical and which accepts a standard bicycle hand-grip and to which brake and shifting levers can be attached in the conventional manner. In addition, grip end 104R has taper 204 which has the same dimensions as tapered recess 504 (Figure 5). In this illustrative embodiment, taper 204 (Figure 6) has a conical shape with a radius angle of 3° (a diameter angle of 6°) and a conical height of 173.77 mm as described above with respect to Figure 5. It is appreciated that taper 204 (Figure 6) can have other tapered shapes such as those described above with respect to tapered recess 502 (Figure 5); however, it is preferred that the shape of taper 204 (Figure 6) match the shape of tapered recess 504 (Figure 5) very closely. Taper 204 (Figure 6) is slightly thinner than grip portion 602, forming a butt 604 therebetween. It is preferred that, in the locked riding position, butt 604 does not contact outer portion 306 (Figure 3) of tapered socket 202 so as not to interfere with direct contact between taper 204 and tapered socket 202 maximizing the amount of direct contact in contact region 206. As a result, grip end 104R is quite rigidly engaged with center portion 102 and play transverse to grip end 104R is eliminated while in the locked riding position. In this preferred embodiment, the gap between outer portion 308 and butt 604 is in a range 222 (Figure 2) of 0.5 to 1.5 mm Grip end 104R (Figure 6) also includes a relatively thin hinge portion 606 which a hole 608 for receiving and engaging hinge pin 212 (Figure 2). When extended and folded into the folding position as shown with respect to grip end 104L (Figure 1), hinge portion 606 fits into notch 302 (Figure 3) which holds the folded grip end in a predetermined rotational orientation with respect to center portion 102 (Figure 1). The predetermined rotational orientation can be upward, downward, forward, or backward with respect to a riding position of a bicycle on which handlebar 100 is installed, or can be any position in between those four positions. The particular predetermined rotational orientation for a particular bicycle depends on the nature in which the particular bicycle is to be stored, carried, and/or folded.

Figure 7 is a cross-sectional view of grip end 104R. Hinge portion 606 includes notches 702 to allow grip end 104R to be folded completely into notch 302 (Figure 3). In addition, grip portion 602 (Figure 7) includes a hollow recess 704 to reduce the weight of grip end 104R without reducing the transverse strength of grip end 104R. Furthermore, grip end 104R includes a bore 706 for housing retention pin 214, spring 218, and plug 216.

Assembly of handlebar 100 is relatively straight forward. Grip end 104R is assembled by inserting retention pin 214, spring 218, and plug 216 through bore 706. Spring 210 is placed at annular notch 308 and retention member 204 is inserted into spring 210 and through tapered recess 502 to enable attachment of grip end 104R to retention member 204 by hinge pin 212. At this point, grip end 104R, retention member 204 and tapered socket 202 are assembled to one another. The assembly, primarily retention member 204 and tapered socket 202 are then inserted into center portion 102 for a press fit. Insertion of this assembly is easier if grip end 104R is inserted into tapered socket 202 in the locked riding position such that grip portion 602 of grip end 104R provides substantial leverage during insertion. The above- described process is repeated for grip end 104L to assemble handlebar 100.

While handlebar 100 (Figure 1) is shown to be straight when grip ends 104R and 104L are in the locked riding position, it is appreciated that the principals described above are applicable to bent or curved folding handlebars as well. For example, grip portion 602 (Figure 6) can be curved back to form a swept-back handlebar used on a cruiser style bicycle or can curved forward, down, and back to form the ubiquitous dropped handlebars of road racing bicycles.

Alternatively, center portion 102 can be slightly bent to provide the typical range of angles of swept-back mountain bicycle handlebars-typically in the range of 3° to 10°.

However, introducing a bend or curve to center portion 102 can interfere with movement of retention member 208 within center portion 102 in the manner described above. Accordingly, in this alternative embodiment, a spring or elastic member is connected between respective retention members of grip ends 104R and 104L to apply the same continuous force opposite arrow A to grip end 104R and resists inadvertent extraction of grip end 104R along the direction of arrow A as applied by spring 210 in the manner described above.

In this illustrative embodiment, center portion 102, end grips 104R and 104L, and tapered sockets 202 are made of 6061 T-6 aluminum.

The above description is illustrative only and is not limiting. The present invention is limited only by the claims which follow.