The present invention relates generally to bicycles and motorcycles, and more particularly to front wheel hub-axle assemblies for the same. Specifically, the present invention provides a novel wheel hub assembly for connecting a wheel rim to the front fork of a bicycle or motorcycle, with this wheel hub assembly comprising an oversized single member hub-axle assembly for attachment to a fork dropout having an enlarged opening.
The present invention has particular application to bicycles referred to as mountain bikes or trail bikes which are typically ridden over rough terrain and/or on steep uphill or downhill slopes. The invention is also applicable to motorcycles commonly referred to as dirt bikes.
As is typical for all conventional bicycles and motorcycles, the front wheel is the steering wheel, that is, it controls the steering of the bicycle or motorcycle. The conventional apparatus used to perform this steering is described below. First, steering handles, or handlebars, are interconnected to the wheel through a fork. The fork typically has parallel legs that extend upward from each side of the wheel axle and connect at the top of the wheel to a central steering tube which is, in turn, attached to the handlebars. The central steering tube is rotatably mounted to the frame of the bicycle in a manner that supports the frame on the wheel""s axle while permitting rotation of the central steering tube and thus allowing the front wheel to turn relative to the frame of the bicycle or motorcycle.
Additionally, it is conventional in the bicycle industry to use xe2x80x9cquick-releasexe2x80x9d mounting devices or hubs for attaching the front wheel to the end piece of each leg of the bicycle front fork. Such end pieces are commonly referred to as dropouts. The use of these quick-release mounts is so commonly in bicycles because they facilitate removal of the wheel for repair, transport, storage, anti-theft, etc.
Further, of particular concern to the xe2x80x9coff-roadxe2x80x9d bicycle rider is the jolting of the front wheel as disturbances in the ground surface, such as rocks, holes, or vertical drops, are encountered. This jolting is transferred to the rider through the wheel, fork, steering tube, steering handles, and ultimately the rider""s arms. In addition to the potential discomfort to the rider, there is the added concern for safety. That is, the steering handles become difficult to control at the instant of a severe jolt being experienced by the rider through the handles.
To overcome this problem of severe jolting, designers of trail and mountain bikes have developed front wheel, shock absorbing suspension systems. These shock absorbing systems have fork legs that include a rigid rod (or inner tube), which is slidable within a rigid sleeve (or outer tube) and a biasing member which can operate pneumatically, hydraulically, elastomerically or with metallic springs, positioned within the rigid sleeve to achieve the xe2x80x9cshock-absorbingxe2x80x9d action. The biasing member extends the fork rods relative to the sleeves, and as obstacles are encountered by the front wheel, the biasing members of the fork""s rigid sleeves collapse as the slidable rods are compressed in the sleeves, thereby absorbing the severe jolt. Additionally, the sliding rod may have a slight degree of rotatability within the sleeve.
Therefore, when an obstacle is encountered directly, the forces are substantially in the same axis as is the fork/suspension system, and the slidable rods are typically displaced uniformly. However, during cornering or other maneuvering, the forces are not in the same axis as the suspension such that torsional and lateral stresses are created, and typically one of the rods is compressed or displaced into the corresponding sleeve more so than the opposite rod. Because the slidable rod has a slight degree of rotatability within the sleeve, high stresses are created at the dropout-to-axle connection when lateral and torsional forces are applied to the wheel in contact with the ground, such as in cornering.
Also, when brakes are applied in stopping or cornering, the brakes push outward and a large amount of torsion acts on the lower two fork tubes. The resistance to this torsion is mainly provided by the wheel axle and the brake arch. Thus, increased rigidity and strength are highly desired at the wheel axle and/or brake arch.
Conventional wheel axles are typically 9 mm in diameter and are detachably mounted to a wheel hub which is typically 20 mm in diameter. With rigid front fork designs (i.e., nonsuspension forks), this is a generally acceptable design because the resistance to the torsional stresses is absorbed through the wheel, fork, steering tube and steering handles in addition to the wheel hub assembly and brake arch. On the other hand, with a front fork suspension system the stresses are different. While uniform compressions relieve stress on the wheel, fork, steering tube, and steering handle, unbalanced compressions, such as from cornering and maneuvering, the stresses on the wheel axle are high. Therefore, increased rigidity and strength in the wheel axle is highly desirable for off-road bicycles and motorcycles, particularly those with front suspensions.
A typical wheel hub assembly for a bicycle or motorcycle includes an axle (or spindle), a hub and bearings (or hub-bearing assembly). In conventional assemblies, the axle is separate and removable from the hub-bearing assembly. Also, conventional fastening systems for attaching the hub-bearing assembly to the axle include received-in threaded holes in a flange on the spindle. Such a conventional system is disclosed in Wilson et al. U.S. Pat. No. 5,238,259 (Wilson). Wilson discloses adjustable dropouts which mount the wheel on the fork assembly where the fastener is removed to permit the shoe installed in the bore to have axial movement. Wilson also discloses an axle including a known quick release and clamp mechanism and operation of the lever to force an end nut toward a lock nut to thus force the end nut and lock nut against the recesses on a bracket to thus lock the axle to the bracket. Simultaneously, a spacer will be forced toward the locknut to thus force the locknut against the surface of the shoe and the spacer will be forced against the opposite surface of the shoe to lock the axle to the shoe. The fastener is then threadably inserted to clamp the shoe in position in the bracket to complete the mounting of the wheel to the fork.
Another conventional fastening system is disclosed in Pong et al. U.S. Pat. No. 5,390,947 (Pong). Pong discloses a device for fastening the wheel to the axle which includes a split tapered collet received between tapered surfaces on the wheel hub and the wheel attachment portion of the axle and a releasable latch mechanism for retaining the collet in a seated relation on the tapered surfaces.
Furthermore, an additional concern for bicycle riders is the weight of the bicycle. A lighter bicycle is more desirable because it takes less exertion on the part of the rider to power and maneuver. As such, manufacturers of high-end performance bicycles and bicycle components are continuously upgrading their bicycles and components to decrease the overall weight of the bicycle. This has typically been accomplished in at least three ways. One is to use lighter materials such as aluminum alloys and carbon-graphite components. Another is to decrease the overall number of components that comprise a bicycle. Yet another is to decrease the thickness of the components used without sacrificing their strength.
Typically, wheel hub assemblies comprise a hollow through axle with a pair of annular bearing assemblies concentrically positioned over the axle and a hollow cylindrical shell, positioned so as to prevent inward movement of the bearing assemblies. Other wheel hub designs utilize a hollow shell having raised ends (or flanges) that is positioned over the axle between the bearing assemblies, with the hub being attached to the wheel at the raised ends by spokes or some other attachment means. Still other designs use attachment rings to attach the wheel hub to the wheel rim and axle, and to separate the bearings. These designs use a hollow shell positioned over the axle to prevent inward movement of the attachment rings.
A further concern to the bicycle rider is ease of repairs when the front tire becomes, for example, punctured and repairs must be made in the field. With typical designs, the axle may become separated from the wheel hub assembly during such repairs. When this occurs, foreign particles may enter the bearing assembly, and thereby cause the wheel hub to fail.
Accordingly, it is desirable to have a wheel hub assembly for bicycles and motorcycles which includes the axle, hub and bearing in a single component. There is also a need for a wheel hub assembly which provides increased rigidity over conventional wheel hub assemblies. There is yet a further need for a wheel hub assembly designed such that the weight would be less than conventional wheel hub and axle systems.
The present invention provides a single piece wheel hub assembly comprising a hub, bearing and axle all-in-one design, as well as providing an improved interface between the front fork dropout and the wheel hub assembly. The present invention accomplishes this by (1) increasing the axle diameter above the conventional 9 mm, preferably to a diameter of 20 mm; and (2) eliminating the conventional two piece design of the hub and axle by press fitting the hub over the axle with the bearing assembly fixed within the hub.
This increased axle diameter and correspondingly increased dropout interface according to this invention yields a more rigid axle, overcomes the disadvantages of the conventional hub and axle assemblies, and imparts more stability to the rider. In conjunction with this wider dropout, there is an increase in the surface area between the axle and the dropout, also adding to the further stability of this completely new interface.
As previously mentioned, high torsional stresses occur at the dropout-to-axle interface, particularly in front suspension bicycles when cornering or maneuvering. To impart additional stability, rigidity and strength, the present invention provides an axle diameter larger than the industry standard of 9 mm. Preferably, the axle diameter is 20 mm, as a synergistic improvement in rigidity is achieved as the axle diameter increases to 20 mm. This discussed in further detail below.
Yet another object of this invention is to provide a single wheel hub assembly, including the axle, hub and bearing, to provide increased strength and stability of the wheel hub assembly. Another benefit of the single piece is the decreased weight of the wheel hub assembly. Yet another advantage of this design is that when the wheel is dismounted from the bicycle, the axle cannot separate from the hub, thereby preventing any foreign particles such as dirt from entering the hub and damaging the bearings. And still another advantage is that separate components could be combined at the front wheel hub of the bicycle.
Furthermore, whereas conventional hub and axle assemblies utilize a device to detachably fasten the axle to the hub, the present invention permanently fastens the hub to the axle. The single wheel hub assembly can be press fit using conventional means in the machining industry.