Patent Application
20090322145
The present invention relates generally to bicycle wheels and, more particularly, to a bicycle wheel having a number of nipple supports than extend radially inward from the rim.
Several aspects of bicycle operation rely on the construction of the bicycle wheel rim. The bicycle wheel rim is constructed to support a tire, to be operatively connected to a hub, and frequently constructed to engage a braking system. Accordingly, rider operation and control of the bicycle depends heavily upon the construction and performance of the wheel rim.
With respect to braking operation, the wheel rim is frequently provided with a generally vertically orientated upstanding wall constructed to operatively engage a brake pad of a bicycle braking system. Such systems are frequently configured to pinch the walls of the rim between the oppositely facing brake pads. Unfortunately, providing a vertically orientated braking wall presents several drawbacks.
The generally vertical orientation of the rim wall to interact with the brakes pads substantially increases the mass and complexity of rim construction. That is, the rims must be constructed to withstand the shear and compression forces generated during braking operations. This is generally accomplished by increasing the thickness and thereby the mass of the rim.
Many wheel rims are constructed to include a pair of inwardly facing hooks that are formed at the radially outward facing ends of the brake sidewalls of the rim. The hooks are constructed to engage corresponding beads formed on the tire. The vertical orientation of the rim sidewalls generally aligns the rim with the tire sidewall such that the interface between the tire and the rim is generally transverse to a plane of rotation of the rim during operation. The tire bead and the rim hook interlock to maintain the engagement between the tire and the rim. During aggressive riding and/or cornering, the forces associated with the interface of the tire and the rim are not necessarily normalized to one another thereby resulting in the concentration of shearing stresses at the interface between the tire and the rim. Although such stresses are not normally problematic, it would be desirable to improve the interface between the rim and the tire to enhance the communication of shear forces therebetween. Understandably, any such alteration must also consider the additional forces communicated to the rim.
Another consideration of rim construction is the interaction of the rim with the respective spokes. Commonly, a number of holes are formed in the rim. Each hole cooperates with a nipple that engages a respective spoke. The nipples are frequently introduced into the holes from a position commonly enclosed by the tire. Accordingly, servicing of a respective spoke and/or nipple frequently requires that the tire be removed from the rim. Such a requirement increases the time and effort associated with servicing a spoke and/or nipple.
Positioning the nipples such that a head portion of the nipple extends generally into the cavity enclosed by the tire presents another complication with respect to tire configurations that have tubes. Generally, the surfaces exposed to the volume enclosed by the rim and the tire needs to be generally smooth to maintain the integrity of the tube. A rim with nipple perforations is not smooth. A rim strip is normally used to smooth over the nipple perforations in order to protect the integrity of the tube. Eliminating the nipple perforations in the rim eliminates the need to use a rim strip. A rim without a rim strip simplifies tire mounting and reduces the overall weight of such a wheel assembly.
Another consideration of rim construction is the possibility to use a tubeless tire. Nipple perforations, present an opportunity for air to leak from the tire. Accordingly, many tubeless wheel assemblies provide alternative methods of sealing the rim, such as the use of a specially formed sealing strip. Rim strip members, whether they protect other wheel components or perform a sealing function, complicate the wheel construction and add weight to the wheel assembly.
Accordingly, it would be desirable to have a system and method capable of providing a bicycle wheel rim that is lightweight, robust and enhances the interface of a tire therewith. Furthermore, it is further appreciated that any such rim should also be aesthetically pleasing and provide a generally continuous or uninterrupted surface to reduce undesired interaction with a tire or tube.
The present invention provides a system and method of forming a bicycle wheel that overcomes one or more of the aforementioned drawbacks. A wheel assembly according to one aspect of the invention includes a number of nipple supports that are attached to a rim. Each nipple support is attached to the rim and extends in a radially inward direction relative to the rim. One or more openings are formed in each nipple support and shaped to cooperate with a respective spoke nipple. A cavity is formed between each nipple support and the rim such that the spoke nipples can be assembled into the supports from a circumferential direction. Such a construction provides a wheel assembly having a rim that is lightweight and generally non-perforated.
Another aspect of the invention usable with one or more features of the above aspect includes a bicycle wheel having a hub that is constructed to cooperate with an axle and a rim that extends circumferentially about the hub. A number of spokes extend from the hub and engage a nipple at a rim facing end of each spoke. A number of nipple mounts are secured to the rim for engaging the nipples. Each nipple mount includes a pair of generally oppositely facing side sections and a mid-section. The side sections are secured to the generally opposite lateral sides of the rim and the mid-section is disposed between the side sections so as to be offset from the rim such that a gap is formed between the mid-section of each nipple mount and the rim. At least one hole is formed in the mid-section of the each nipple mount and cooperates with a respective nipple such that each spoke is tensioned between a respective nipple mount and the hub.
Another aspect of the invention usable with one or more of the features discussed above includes a method of forming a bicycle wheel that includes providing a hub and a number of spokes. A rim having a generally round circumferential shape and a generally non-perforated body is positioned about the hub. A number of spoke mount cradles are provided. Each spoke mount cradle includes at least one nipple hole. The number of spoke mount cradles are secured to the rim in a circumferentially spaced manner such that opposite circumferential ends of each spoke mount cradle are accessible and each nipple hole is offset radially inward from the non-perforated body of the rim. A number of nipples are provided such that each nipple cooperates with a respective nipple hole to tension a respective spoke between the hub and a respective spoke mount cradle.
A further feature of the invention usable with one or more of the aspects above is to form at least two openings in each mount cradle or nipple support to cooperate with at least two nipples. Such a configuration provides a wheel assembly having at least twice as many spokes as spoke mounts.
Another aspect of the invention to be considered in addition to one or more of the above features and aspects is to provide the nipple supports with openings that are laterally offset from a plane of rotation of the rim to achieve a desired lateral performance of the wheel assembly.
Preferably, the oppositely facing side walls of each nipple support are bonded to the generally oppositely facing and upwardly extending legs of the cross-section of the rim. It is further envisioned that any of the supports discussed above be formed from a carbon fiber based material, a composite based material, or a metal material.
These and various other features and advantages of the present invention will be made apparent from the following detailed description and the drawings.
The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention.
In the drawings:
Bicycle 10 includes a front brake assembly 50. Front brake assembly 50 includes an actuator 52 that is attached to handlebars 16 and a caliper having a pair of brake pads 53 that are positioned on generally opposite sides of a rotor. Brake pads 53 are constructed to engage the rotor thereby providing a stopping or slowing force to front wheel assembly 12. Alternatively, front wheel assembly 12 could be provided with a brake caliper positioned to engage a brake wall 54 positioned radially outward relative to nipple supports 48.
Bicycle 10 includes a rear wheel assembly 56 that includes a rear wheel brake assembly 58. Brake assembly 58, unlike front disc brake assembly 50, includes a caliper 62 and a set of brake pads 63 that are positioned on generally opposite lateral sides of wheel assembly 56. Understandably, either or both of front and rear wheel brake assemblies 50, 58 could be provided as rotor or disc type brakes such as front brake assembly 50 wherein the brake assembly is mounted nearer either of front axle 40 or a rear axle 64 or as a system configured to configured to cooperate with the wheel rim, such as brake system 58.
A seat stay 65 and a chain stay 66 offset rear axle 64 from a crankset 68. Crankset 68 includes a pedal 70 that is operationally connected to a chain 72 via a chain ring or sprocket 74. Rotation of chain 72 communicates a drive force to a rear section 76 of bicycle 10. A gear cluster 78 is positioned about axle 64 proximate rear section 76. Gear cluster 78 is generally concentrically orientated with respect to rear axle 64 and includes a number of variable diameter gears 79 that each cooperate with chain 72.
Gear cluster 78 is operationally connected to a hub 80 of rear wheel assembly 56. A number of spokes 82 extend between hub 80 and a rim 81 of rear wheel assembly 56. It is appreciated that although rear wheel assembly 56 is shown as having a number of spokes that directly engage rim 81, rear wheel assembly 56 could also be constructed to include one or more nipple mounts that would extend inward relative to rim 81 and cooperate with one or more of spokes 82 in accordance with the construction of front wheel assembly 12. That is, bicycle 10 could be provided with one or more wheels equipped with nipple supports 48. In addition to providing a front or rear wheel, it is further appreciated that wheel assembly 12 is applicable to bicycles provided as a rugged terrain, mountain, or off road type bicycles and bicycles intended for operation on generally smooth or paved surfaces, i.e. road bikes.
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The generally non perforated construction of body 84 of rim 46 allows rim 46 to be constructed with an overall thinner wall thickness. Furthermore, nipple supports 48 distribute the lateral and torque load associated with each of the spokes 44 secured thereto over a greater area of the body 84 of rim 46. Distributing the load associated with any given spoke over a greater area of rim 46 allows the overall thickness of rim 46 to be reduced. Rim 46 has a generally uniform cross-sectional area across nearly the entirety of the circumference of rim 46 thereby simplifying the construction of rim 46 while reducing the overall weight of wheel assembly 12. Furthermore, as rim 46 of wheel assembly 12 includes no spoke perforations through body 84, wheel assembly 12 overcomes the attributes commonly associated with rim and sealing strips as discussed above. In addition to being convenient to assemble and service, such a construction provides a wheel assembly that is lightweight, robust, and can withstand the rigors of aggressive riding.
The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.
