Vehicle handlebar

A handlebar suitable for use on vehicles such as motorcycles, bicycles, tricycles and jet skis is described. The handlebar has a constant outside diameter, but has an inside diameter at its center section different than the inside diameter at its end sections. The handlebar may comprise an outer tube of standard outer dimensions and an inner tube centered in the outer tube for added rigidity in the central positions. The handlebar provides added rigidity over typical handlebars while permitting use of standard size components with the handlebar. A method of manufacturing such a handlebar is also described.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to handlebars for powered and 
unpowered vehicles such as motorcycles, bicycles, tricycles, all terrain 
vehicles and jet skis. 
2. Description of Related Art 
Conventional handlebars for vehicles such as off road motorcycles, dirt 
bikes, ATBs (all terrain bikes), and BMX (bicycle moto-cross) bikes 
typically comprise a bent bar with a handle at each end. A front plan view 
of a common prior art handlebar 100 is illustrated in FIG. 1. FIG. 2 is a 
top plan view of the prior art handlebar 100. The common prior art 
handlebar 100 comprises a bent, elongated tube 110 having a central 
section 120 and oppositely disposed end sections 130 and 140 which are 
mirror images of one another. The tube 110 typically has a uniform 
diameter 160. 
The handlebar art has generally adopted 7/8 inch as a standard outside 
diameter for handlebar tubes. Hence, a wide array of complementary parts 
may be used in conjunction with a standard handlebar. For example, grips 
or handle members, preferably made of polyvinyl or rubber, can be fitted 
over a portion of each end section 130, 140. Other parts commonly used in 
conjunction with a handlebar include clamps for coupling the handlebar to 
a steering system of the vehicle, and various clamps for coupling cables, 
brake and clutch levers, and other devices to the handlebar. 
Standardization on the 7/8 inch diameter has resulted in substantial 
economies to thereby reduce costs, increase availability and 
interchangeability of parts in general, and increase the variety of parts 
available. 
However, while the diameter of approximately 7/8 inch provides for ideal 
interoperability with other parts, it typically provides the middle 
section 120 and bent sections 132 and 142 with an undesirably thin member 
for absorbing the stresses, strains and shocks imparted to the handlebars 
100 from vigorous riding. Handlebars are frequently used in high stress 
situations such as off road riding or dirt bike riding, and typical prior 
art handlebars often fail under the high stress of such situations. 
In order to strengthen the handlebars, prior art handlebars commonly 
include a crossbar 150 which is attached to the handlebar 100 at the 
locations of the intersection of the end section 130 with bent section 132 
and the intersection of the end section 140 with bent section 142. There 
are two conventional methods by which the crossbar 150 is attached. In one 
method, the crossbar 150 is welded in place. In the second method, the 
crossbar 150 is clamped in place with a pair of clamps that are tightened 
with bolts. 
In operation, the handlebar 100 is attached to a vehicle along the length 
of the center section 120 and usually at two spaced apart locations, and 
such that the crossbar 150 faces the rider of the vehicle. Because the 
center section 120 and bent sections 132, 142 are typically not strong 
enough to withstand large forces, the crossbar 150 is provided to prevent 
the handlebars 100 from buckling if the vehicle should bump into something 
or crash to the ground. However, in the event of an impact, the crossbar 
150 typically causes a permanent compression set to occur in the tube 110. 
This is undesirable because subsequent impacts induce additional 
compression, which may lead to failure of the handlebar 100. In addition, 
the crossbar 150 is typically extraneous to steering the vehicle, so it 
adds weight for the greater portion of use while only improving 
performance for a small portion of use. Furthermore, because of the 
direction of attachment of the crossbar 150, it typically only reinforces 
the handlebars 100 in the vertical direction, not in the horizontal 
direction. 
Therefore, the major disadvantage of prior art handlebars is that they 
require a crossbar for strength. However because the crossbar provides 
rigid support at its attachment points to the bent tube, it forces stress 
concentrations there, which tend to take a permanent set in falls. The 
crossbar also typically constrains shock absorption by tube 110 which 
would soften shock loads to the rider when gripping the ends 130, 140 of 
the handlebar. 
A handlebar which resolves some of the above problems is disclosed in U.S. 
Pat. No. 5,117,708, entitled "Handlebars for Motorcycles, Dirt Bikes, All 
Terrain Vehicles and Jet Skis," to Boyer et al. According to Boyer, there 
is provided a hollow-tube handlebar without a crossbar, but having an 
outer diameter which is larger in the center, and which tapers to the 
ends. Further according to Boyer, the inner diameter of the tube should 
also be tapered such that it is larger in the center and tapers in to the 
ends. Boyer teaches that any cross-section of the tube should have the 
same amount of material, such that the tube has its thickest walls at the 
end sections and thinnest walls in the center section. 
Regardless of whether such a handlebar is more durable than a standard 
handlebar, such a handlebar suffers from substantial problems. First, 
because the center of the handlebar is thicker than the ends, at least one 
of the center or the ends is necessarily a non-standard size. This means 
that, if the center is thicker than the standard of 7/8 inch, then a 
special clamp is required. If the ends are thinner than the standard of 
7/8 inch, then special grips and other handle members are required. 
Because such special parts are necessary, there is typically incurred 
increased cost of parts, reduced availability and interchangeability, and 
limited selection. Vehicles using high strength handlebars as taught by 
Boyer are commonly used in remote locations, but replacement parts to fit 
non-standard size handlebars may not be available. Thus, if any part of 
the handlebar assembly breaks, spare parts may not be available unless 
carried with the vehicle. 
An additional problem with such handlebars is that, because of the relative 
thickness of the ends, the end sections have been found to vibrate more 
than the center section, thereby increasing rider discomfort and fatigue. 
Since fatigue is a major factor in vehicle accidents of any kind, this 
added vibration effect is undesirable. 
Thus, there is a significant need for an improved configuration for 
handlebars which provides greater strength, improved shock absorption, and 
improved steering capability, while preserving the numerous advantages 
inherent in standard uniform diameter handlebars. These objects and others 
are provided in the vehicle handlebar of the present invention. 
SUMMARY OF THE INVENTION 
The invention is directed to a handlebar which provides greater durability 
than typical handlebars and retains the industry standard outer diameter. 
To achieve the desired goals, a handlebar of the present invention has an 
outer diameter at the center and ends of 7/8 inch to provide 
interchangeability of parts. To improve strength, the inner diameter of 
the handlebar is varied, such that the center has a smaller inner 
diameter, and the ends have a larger inner diameter. 
According to one embodiment, the handlebar comprises a single tube 
manufactured to have varying inner diameter. 
According to a second embodiment, the handlebar comprises an outer tube and 
an inner tube disposed within and centered with the outer tube. The outer 
tube provides a constant outer diameter. Preferably, the outer diameter is 
7/8 inch. The handlebar defines a hollow which extends through and between 
the end sections and through the center section. The inner tube, since it 
is disposed at the center section of the outer tube, provides a thicker 
wall to the center section than the wall of the end sections. Hence, the 
center section provides increased strength at the clamp, and the end 
sections provide reduced vibration. 
The end sections may include bent sections proximate the center section 
which are oval shaped. The inner tube may be made long enough to extend to 
the bent sections or may only extend along the center.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS 
A vehicle handlebar according to an embodiment of the invention is 
described. Throughout this description, the preferred embodiment and 
examples shown should be considered as exemplars, rather than limitations 
on the apparatus of the present invention. 
A handlebar suitable for use on vehicles such as motorcycles, bicycles, 
tricycles and jet skis will now be described. Handlebars in accordance 
with the invention provide added strength over standard handlebars. Hence, 
handlebars of the present invention are especially well suited for 
off-road use, such as for motorcross motorcycles and bicycle moto-cross. 
A hollow handlebar typically has a rounded, circular wall. At any point 
along the handlebar, the thickness of the wall should be considered to be 
the distance from the outside face of the wall to the inside face of the 
wall. For a handlebar having a circular cross section, the thickness is 
half the difference between the outer diameter and the inner diameter. 
Handlebars in accordance with the present invention may take at least two 
forms. First is the double-tube form. Accordingly, the handlebar comprises 
a main outer tube, with an inner tube to provide added support. Second is 
the single tube embodiment, wherein the inner diameter of the tube is 
varied in accordance with the invention for added strength. The 
double-tube embodiment will be first described, then the single tube 
embodiment will be described. 
Referring now to FIG. 3A there is shown a partial front cross section of an 
embodiment of a handlebar in accordance with the invention. The handlebar 
comprises a first end section 320, a center section 310, and a second end 
section (not shown) which mirrors the first end section 320. The first end 
section 320 preferably comprises a bent section 340 proximate the center 
section 310 and a distal end 330. The bent section 340 preferably 
comprises a proximal bend 342, a middle portion 343 and a distal bend 341. 
The handlebar is bent at the proximal bend 342 at an angle .phi..sub.1 of 
approximately 45.degree.. The handlebar is bent at the distal bend 341 at 
an angle .phi..sub.2 preferably less than 45.degree.. 
As shown in FIG. 3B, which is a partial top view of the handlebar shown in 
FIG. 3A, the distal bend 341 is also preferably bent at a small angle 
.phi..sub.3 in a different plane than the proximal bend 342. 
Referring now to FIG. 3C, there is shown a cross section of the handlebar 
shown in FIG. 3A along reference line 3C. At the center section 310, there 
are provided an outer tube 360 and an inner tube 350. The handlebar 
preferably also defines a hollow 370, which preferably extends from and 
through the end section 330 through the center section 310 to the second 
end section (not shown), i.e., the complete length of the handlebar. The 
inside of the end 350a of the inner tube is preferably tapered. 
Preferably, the inner tube 350 extends from the distal bend 341 through 
the center section 310. The center section 310 and the distal end 330 
preferably have circular cross sections. Thus, the inner perimeter and 
outer perimeter of the handlebar are preferably circular. However, the 
bent section 340 preferably has an elliptical shape and an oval cross 
section. It has been found that bent sections having the preferred oval 
cross section provide additional rigidity. Since other parts typically are 
not attached at the bent section, a non-circular outer form may be used at 
the bent sections. 
The center section preferably has an outer diameter of 22 mm. The bent 
section 340 preferably has a side diameter of 26 mm and a top diameter of 
22 mm. The distal end 330 preferably has a diameter of 22 mm. The 
thickness of the wall at the ends is preferably 3.55 mm, and the thickness 
of the wall at the center is preferably at least 6.5 mm. 
Referring now to FIG. 5, there is shown a partial side section of a 
handlebar in accordance with the invention. This handlebar includes a 
center section 510 and an end section 520. The end section 520 includes a 
bent section 540 and a distal end 530. The bent section 540 comprises bend 
542, a middle portion 541, and a distal bend 543. The handle bar comprises 
an outer tube 560 and an inner tube 550. In this embodiment, the outer 
diameter of the handlebar is constant. Thus, the outer diameter of the 
center section 510, the bent section 540 and the distal end 530 are all 
the same. Furthermore, the bent section in this embodiment has a circular 
cross-section. 
As shown in FIG. 3A, the end 350a of the inner tube 350 is preferably 
tapered. More preferably, the entire inner tube is selectively tapered, 
such that the wall thickness declines gradually or in several decrements 
from the center to each of the ends. 
When used, a handlebar in accordance with the invention provides superior 
strength and reduced vibration as compared to typical handlebars. This is 
in part because the inner tube and the outer tube move together. 
Furthermore, added rigidity is provided by insertion of the inner tube 
inside of the outer tube. 
There will now be described a preferred manufacturing process for the 
two-piece handlebar shown in FIGS. 3 and 5. Referring now to FIG. 6A, 
there is shown a first cylindrical block 660a and a second cylindrical 
block 650. Preferably, the cylindrical blocks comprise solid aluminum. The 
first block 660a will become the outer tube, and the second block 650 will 
become the inner tube. In a first step, the first block 660a is forged to 
a large cup 660b as shown in FIG. 6B. The cup 660b comprises a side wall 
661b having circular cross-section and an end wall 662. The side wall 661b 
defines a hollow 670. In a second step, the cup 660b is heated and drawn 
to be longer and thinner (660c) as shown in FIG. 6C. In the second step, 
the side wall 661b is made thinner and more narrow. In a third step, the 
second block 650 is also forged to a cup and drawn but is shorter and of 
smaller diameter than the first cup 660c. Referring now to FIG. 6D, in a 
fourth step the inner cup 650d is inserted into the outer cup 660d. At 
this point in the process, the outer cup 660d has a larger inner diameter 
than the outer diameter of the inner cup 650d. Next, in the fifth step, 
the outer cup 660d is drawn a third time so as to fit the outer cup 660e 
tightly to the inner cup 650e. Finally, the end 662e is removed and the 
handlebar assembly is bent to a desired shape by well-known bending 
techniques. 
A handlebar in accordance with the invention does not require pins, glue, 
or other holding means. The inner tube is secured within the outer tube by 
a friction fit. The friction fit provides additional advantages, since the 
inner bar and outer bar may flex at separate rates. Thus, stress buildup 
is additionally avoided. 
The inner tube and outer tube need not be of aluminum. For example, the 
tubes may comprise plastic, fiberglass, steel, titanium, or any other 
material which provides a desired amount of strength. In addition, the 
inner tube and outer tube need not be made of the same material. For 
example, the outer tube may be made of extruded polyvinyl chloride (PVC) 
and the inner tube may be made of aluminum. 
Furthermore, more than one inner tube may be provided. Several inner tubes 
of varying inner diameter may be disposed within an outer tube along the 
length of the handlebar. Thus, a tube having a small inner diameter would 
be disposed at the center, and tubes having a larger diameter would be 
disposed at other points, such as at the bent sections. Also, several 
inner tubes may be nested, such that in cross-section, several inner tubes 
may be seen. Accordingly, wall thickness may be varied simply by including 
several inner tubes. 
It has been found that the double-tube embodiment of the invention provides 
substantially greater strength than typical cross-bar handlebars. The 
double-tube embodiment provides equivalent performance to typical 
handlebars having varying outer diameter. Hence, greater strength is 
provided by handlebars in accordance with the invention, without 
necessitating a crossbar. 
Referring now to FIG. 7A, there is shown a front cross section of another 
embodiment of a handlebar in accordance with an aspect of the invention. 
This embodiment has the same general outward appearance as the first 
embodiment. However, in cross section, this single bar embodiment differs 
from the first embodiment and conventional handlebars. Unlike the first 
embodiment described above, the handlebar shown in FIG. 7A is constructed 
of a single tube 760. Like the first embodiment, this handlebar comprises 
a center section 710 and two end sections 720, 780. The end sections 720 
and 780 are preferably mirror images of one another. The end section 720 
comprises a bent section 740 and a distal end 730. The bent section 
includes a proximal bend 742, a middle portion 741 and a distal bend 743. 
The thickness of the tube 760 is preferably continuously varied from one 
distal end 790 to the other distal end 730. Referring now to FIG. 7B, 
there is a shown a cross section of the center section along reference 
lines 7B. As can be seen, the center section has a substantially circular 
cross-section. Referring now to FIG. 7C, there is shown a cross-section of 
the tube at the middle portion 741 of the bent section 740 of the 
handlebar of FIG. 7A. As can be seen, the tube 760 at this point has a 
substantially oval cross-section. Referring now to FIG. 7D, there is shown 
a cross-section of the handlebar of FIG. 7A at the distal end 730. At the 
distal end 730, the tube preferably has a circular cross-section. The 
thickness of the tube 760 is preferably greatest in the center section 
710, and thinnest at the distal ends 730, 790. However, the diameter of 
the tube is preferably constant in the center section 710 and the distal 
ends 730, 740, and is preferably 7/8 inch. Although the bent section is 
preferably oval in cross-section, this part of the tube preferably also 
has a shortest diameter of 7/8 inch. 
The single tube embodiment may be manufactured by drawing, or rolling. 
Differences in inner diameter may be achieved by expanding the inside of 
the tube at the ends, or by drilling or reaming out the inside of the tube 
wall. 
The cross-section of the tubes need not be perfectly circular. As shown in 
FIG. 4, an outer tube 460 may have a star-shaped inner surface as provided 
by cut outs 461. The central portion of the tube 460 may have other 
shapes, such as a square or hexagon. It has been found that the star shape 
as shown in FIG. 4 provides advantages to the handlebar of the present 
invention by reducing total weight of the handlebar without sacrificing 
significant strength. Other shapes may also be used, such as rectangles or 
other polygons. 
Although exemplary embodiments of the present invention have been shown and 
described, it will be apparent to those having ordinary skill in the art 
that a number of changes, modifications, or alterations to the invention 
as described herein may be made, none of which depart from the spirit of 
the present invention. All such changes, modifications and alterations 
should therefore be seen as within the scope of the present invention.