Patent Publication Number: US-2009236902-A1

Title: Spoked Bicycle Wheel

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/038,444, filed on Mar. 21, 2008, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to bicycle wheels and more precisely to the spokes of aerodynamic bicycle wheels. 
     2. Background of the Related Art 
     Cycling has served many purposes in human history. From construction of a bicycle, to the first recorded road race in 1868, bicycle riding has extended beyond its functional purpose of transportation. In 1900 Belgium, France, Italy, Switzerland, and the United States founded the International Cycling Union (UCI). This Union still functions today, hosting road bicycle races world wide and promoting all forms of cycling. 
     Recent years have seen the popularity of road bicycle races skyrocket, with racers, such as Lance Armstrong, becoming icons of American popular culture. Cycling has become more popular at all levels, from adult weekend athletes, to dirt bike riders, and even to children&#39;s bicycle riding. 
     While much of the bicycle structure (e.g. two wheels, handle bars, gears, breaking mechanism) has remained consistent, the materials from which these parts are constructed and the detailed design have changed. These changes have led to lighter weight bicycles with aerodynamic shapes. 
     The aerodynamic nature of a bicycle is somewhat inhibited by the rider, who blocks much of the airflow. A secondary and more malleable portion of the bicycle, which creates wind resistance, is the wheel. 
     A typical bicycle wheel can have up to 32 spokes in certain double crossing configurations, and while these more traditional bicycle wheels typically have rounded spokes, the spokes can be made in an elliptical or bladed shape for the purposes of aerodynamics or aesthetics. 
     Various aerodynamic wheels have been developed for bicycle racing. These include, for example, wheels having no spokes, such as disc wheels; wheels having very few spokes, such as the Hed 3 manufactured by Hed; and wheels having many bladed spokes such as the Stinger or Jet 50 manufactured by Hed or the Ksyrium-SL-Premium manufactured by Mavic. 
     U.S. Pat. No. 5,080,444 to Hopkins et al. (Hopkins) discloses spokes with a leading and trailing edge. These spokes are aerodynamically shaped, having a width to thickness aspect ratio greater than 3.0. 
     U.S. Pat. No. 6,086,161 to Luttgeharm et al., (Luttgeharm) discloses a wheel, with at least one spoke, where the cross section of the spoke varies from first to second end. Luttgeharm does not disclose any surface features on the spokes. 
     U.S. Pat. No. 5,246,275 to Arredondo Jr. (Arredondo), entitled Wheel for Bicycles and Method of Producing, discloses the use of aerodynamic spokes. Arredondo defines “aerodynamic shape” to mean the cross-section of the spoke in the axial direction has a length to thickness ratio of at least about two. 
     U.S. Pat. No. 7,114,784 to Ording et al. (Ording) discloses a disc type wheel with surface features designed to create turbulence in the boundary layer. The surface features can be uniform or random in place and size. Ording describes a disc shaped wheel which has no spokes. The patent directs the practitioner to use the surface features on the face of a disc type wheel. The Ording reference does not apply the disclosed surface features to spokes. 
     U.S. Pat. No. 6,431,498 to Watts, et al. (Watts) discloses a plurality of aerodynamic protrusions spaced laterally along the leading edge of an airplane wing. These include: aircraft, including stators, rotors, fans and various appendages; watercraft, including rudders, conning towers, sailboat keels, sailboat masts, submarine dive planes; and land vehicles including car spoilers. 
     In  A whale of a tale  an article published May 14, 2007, Tyler Hamilton described the use of scalloped edges for wind-turbine blades.  Mimicking Humpback Whale Flippers May Improve Airplane Wing Design,  published in June of 2004, discloses the use of scalloped edges on airplanes. 
     A Journal of Aircraft article by David S. Miklosovic, Mark M. Murray, &amp; Laurens E. Howle,  Experimental Evaluation of Sinusoidal Leading Edges,  Journal of Aircraft, Vol. 44, No. 4, 1404-1407, (2007), studied the mechanism by which the scalloped edge provides benefit. The authors report a study on two wings, one in which half of the span was scalloped and the other half tapered, and the other wing had scallops covering the full span of the wing. Scallops were reported to have a largely 3-D benefit inducing vortical flow. In the full-span wing this vortical flow triggered early separation but in the half-span wing, effectiveness was enhanced because the span-wise stall progression was inhibited thereby extending the operating parameters with little penalty on performance. Performance of an object bounded on both ends, such as a spoke of a bicycle wheel, was not studied. 
     Accordingly, it is a goal of the present invention to improve upon the aerodynamic nature of a bicycle wheel. It is also an objective of the present invention to improve upon traditional airfoil spoke designs of a bicycle wheel by modifying the spokes. An additional objective of this invention is to improve the aerodynamics of a bicycle wheel without increasing the weight of the wheel. The aerodynamic protrusions can provide two-dimensional and three-dimensional aerodynamic benefits. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side perspective view of a bicycle wheel according to the present invention; 
         FIG. 2  is a leading edge view of a spoke according to the present invention; 
         FIG. 3  is a side plan view of the wheel; 
         FIG. 3A  shows the wheel of  FIG. 3  with the rim removed to show the spoke; 
         FIG. 4  is a side plan view of a spoke; 
         FIG. 5A  is a side plan view of an alternative spoke design; 
         FIG. 5B  is a side plan view of a still further alternative spoke design; 
         FIG. 6A  illustrates an alternative configuration for the aerodynamic protrusions formed along the spoke; 
         FIG. 6B  illustrates a still further alternative configuration for the aerodynamic protrusions formed along the spoke; 
         FIG. 7A  illustrates a side plan view of a scallop shaped protrusion formed in accordance with a preferred embodiment of the present invention; and 
         FIG. 7B  illustrates a top plan view of the scallop shaped protrusion illustrated in  FIG. 7A . 
     
    
    
     SUMMARY OF THE INVENTION 
     These and other features and objectives of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed as being illustrative only and not intended to define of the limits and scope of the invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A wheel according to the present invention includes a hub, rim, tire, and at least one spoke including at least one aerodynamic protrusion on the leading edge of the spoke. Preferably, the spoke is airfoil shaped with a plurality of aerodynamic protrusions along the leading edge of the airfoil. More preferably, the aerodynamic protrusions occur along the leading edge in a sinusoidal pattern with the space between the aerodynamic protrusions creating valleys. 
       FIG. 1  illustrates a side perspective view of a bicycle wheel  10  according to the present invention. The wheel includes a hub  16  at its center, a rim  12  at its outer edge, a tire  22 , and at least one spoke  18 . The leading edge  24  of the spoke  18  exhibits aerodynamic protrusions  14  followed by valleys  15  in a sinusoidal pattern as described in greater detail below. 
     The tire  22  of the present invention is configured to be disposed on the outside of a rim  12  to provide traction between the road and the wheel  10 . The rim  12  of the bicycle wheel  10  defines the outside portion of the wheel  10  to provide external support to the wheel  10 . The rim  12  is further configured to receive the tire  22  and a first end spoke  18  on the inside of the rim  12 . 
     The hub  16  is configured to operatively receive a second end of the at least one spoke  18  of the wheel  10 . The hub  16  is further configured to define the center of the wheel, and is centrally disposed with respect to the rim  12 . The hub  16  can be made from any suitable material. 
     The spoke  18  is configured to provide internal support to the wheel  10  and to support the hub  16 . The spoke  18  is further configured to connect to the rim  12  at a first end and the hub  16  at a second end. The spoke  18  includes a leading edge  24 , aerodynamic protrusions  14  and valleys  15 . The leading edge  24  is the front portion of the spoke  18  and the portion that first contacts the air. 
     The spoke  18 , hub  16 , and rim  12  can be made of any type of material commonly used for wheels. For example, the spokes  18 , hub  16  and rim  12  can be composed of carbon fiber, thermoplastic polymer, aluminum alloy, magnesium alloy, glass fiber, wood, steel, titanium, titanium alloy, combinations of these materials, or other known materials. 
     The tire  22  can be a tubular tire, clincher tire, or any other suitable bicycle tire. If it is a clincher tire, it can be made with steel wire, Kevlar® (para-aramid synthetic fiber), fabric, such as for example cotton, silk, polyamides or nylon cord, rubber, silicon, carbon black, any combination of these, or any other known clincher tire material. If the tire is a tubular tire, it can be made with fabric, such as for example cotton, silk, polyamides or nylon cord, rubber, silicon, carbon black, any combination of these, or any other known tubular tire material. The inner tube of the clincher or tubular tire can be made of latex rubber, butyl rubber, or any other suitable inner tube material. 
     The spoke  18 , hub  16  and rim  12  can be hollow, partially filled, or solid. If the foregoing components are hollow or partially filled they can be filled with foam, vinyl polymer, or other commonly known fillers. The hub  16 , rim  12 , and spokes  18  can be cast from a solitary mold or can be separately formed. If separate, the spokes  18  join to both the rim  12  and the hub  16 , and can be spaced at uniform angles from the hub  16 . The spokes  18  can be made from the same materials as those of the wheel  10  or different materials. Preferably the hub  16 , rim  12 , and the spokes  18  are made from a single molding process and are monolithically formed. 
       FIG. 2  is a leading edge view of the spoke  18 . The spoke  18  has a length  27  and is preferably airfoil shaped with a leading edge  24  and a trailing edge  26 . The spoke  18  includes aerodynamic protrusions  14  disposed along the leading edge  24  of the spoke  18 . In between the aerodynamic protrusions  14  are the valleys  15 . 
     The spoke  18  includes the leading edge  24  including at least one aerodynamic protrusion  14  and at least two corresponding valleys  15  to either side of the protrusion present in a sinusoidal pattern. Preferably the spoke includes multiple aerodynamic protrusions  14  and corresponding valleys  15  which are configured to reduce aerodynamic drag caused by both the spoke  18  and wheel  10  as they move through the surrounding air. The aerodynamic protrusions  14  can be formed along any portion of the spoke  18 . They can occur, for example, along ¼, ½, ¾ the length of the leading edge  24  of the spoke  18 ; most preferably, the aerodynamic protrusions  14  cover the entire length of the leading edge  24  of the spoke  18 . The aerodynamic protrusions  14  may be formed in a uniform pattern or a random pattern along the length of the leading edge  24  of the spoke  18 ; preferably they are formed in a uniform pattern. 
     In an alternate embodiment, the aerodynamic protrusions  14  may be formed along both edges leading edge  24  and trailing edge  26  of the spoke  18 . The aerodynamic protrusions  14  can be spaced evenly along the leading edge  24  and create a smoothly varying, alternately forward and aft sweep along the leading edge  24  relative to the direction of air flow along the leading edge  24 . 
     The size of a wheel  10  can vary depending on the height of the rider and other factors. Accordingly, the length  27  of the spoke  18 , from the rim  12  to the hub  16  can also vary. Preferably, the spoke  18  is from about 4 inches to about 15 inches. More preferably, the spoke  18  is from about 6 inches to about 10 inches. Most preferably, the spoke  18  is about 7 inches in length  27 . 
     The number of spokes  18  per wheel  10  can be from 1 to 40 spokes  18 . Preferably it has from about 2 to about 20 spokes  18 ; more preferably from about 3 to about 5 spokes. 
     The spokes  18  of the bicycle wheel  10  can be at any location within the wheel  10 . The spokes  18  can be made to be removable, like, for example, the spokes of the Ksyrium SL Premium wheel manufactured by Mavic. The spokes  18  can be adjustable, for example rotating on the axis between the hub  16  and the rim  12  so as to be angled as necessary for optimal aerodynamics based upon the wind conditions. Alternatively, the spokes  18  can be permanently directed and stationary in the preferred aerodynamic orientation. Preferably, the spokes  18  are connected within the bicycle wheel  10  at the rim  12  and the hub  16 . 
       FIG. 3A  is a side plan view of a wheel  10  and  FIG. 3A  shows the wheel of  FIG. 3 , with the rim  12  removed to expose the spoke  18 . As stated above, the spoke  18  preferably has an airfoil shape including leading  24  and trailing  26  edges. Preferably, the aerodynamic protrusions  14  and corresponding valleys  15  repeat sinusoidally. 
     The spoke  18  as illustrated in  FIG. 3A  has a depth  25  and is shaped like an elongated tear drop. The trailing edge  26  ends in a sharp point and the leading edge  24  is wider and somewhat rounded. The leading edge  24  includes aerodynamic protrusions  14  and valleys  15  providing a repeatedly arced leading edge  24 . 
     The protrusion  14  is configured to disrupt the airflow  17  along the leading edge  24  of the spoke  18 . The disruption of airflow  17  caused by the protrusions  14  creates a plurality of airflows  17  and forces the airflows  17  into the valleys  15  to either side of the protrusion  14 . The valleys  15  are configured to create and accelerate vortices  19  of air  17 , causing the air  17  to roll around the leading edge  24  of the spoke  18 . The protrusions  14  reduce the tendency of air to run down the width of the spoke  18  and fly off at the trailing edge  26 , causing noise, instability and a loss of efficiency. 
     The trailing edge  26  is the side of the spoke opposite and parallel to the leading edge  26 . The trailing edge  26  is configured to be sharply pointed and straight. The trailing edge  26  is further configured to allow vortices  19  of airflows  17  to move from the valleys  15  over the width of the spoke  18  and rejoin the primary air stream  21 . The sharp straight trailing edge  26  is further configured so that the amount of airflow  17  on either side of the spoke  18  rejoins the main air stream  21  in an efficient and smooth manner without creating additional turbulence. 
     At the mid-point between the leading edge  24  and trailing edge  26  of the spoke  18 , the depth  25  of the spoke  18  is the distance between the two sides of the spoke  18  from about 0.1 to about 1.50 inches. Preferably the depth  25  is from about 0.25 inches to about 1.0 inches. More preferably, the depth  25  is from about 0.5 inches to about 0.8 inches. Most preferably, the depth  25  is about 0.75 inches. 
     In operation, the wheel  10  described above can be utilized on any wheeled transportation which makes use of wheels having spokes. The wheel  10  is preferably applied to both wheels of a racing bicycle. Use of the wheel  10  having spokes  18  with aerodynamic protrusions  14  reduces the drag caused by both the spokes  18  and the wheel  10 . The spoke  18  formed with aerodynamic protrusions  14  enhances the efficiency of the wheel  10 . This enhanced wheel efficiency leads to an increase in the efficiency of the bicycle to which it is applied. Accordingly, a rider can expend less energy to maintain the same speed or the same amount of energy and attain a greater speed. 
       FIGS. 7A and 7B  illustrate a repeatedly arced or scallop-shaped protrusion  14  and antipodean arced valley  15 . The aerodynamic scallop-shaped protrusion  14  and antipodean valley  15  may be configured to provide aerodynamic benefit to the spoke  18 . The aerodynamic protrusion  14  has a height  32  and width  30 . The spoke  18  of wheel  10  has a chord  34 . 
     The chord  34  of the spoke  18  can vary from about 0.25 to about 5 inches. Preferably, the chord  34  is from about 0.5 to about 4 inches. More preferably, the chord  34  is from about 1 inch to about 3.5 inches. Most preferably, the chord  34  is about 3 inches. The chord  34  is measured from the leading edge  24  to the trailing edge  26 . 
     The height  32  of each aerodynamic protrusion  14  is a percentage of the chord  34  of the spoke  18 . The height  32  can be from about 0.25% of chord  34  to about 100% of the chord  34 . Preferably, the height  32  of the aerodynamic protrusion  14  is from about 0.75% of the chord  34  to about 50% of chord  34 . More preferably, the aerodynamic protrusion  14  is from about 2% of the chord  34  to about 10% of the chord  34 . For a typical adult racing bicycle the height  32  of the aerodynamic protrusion  14  is preferably about 4% of chord  34 . Furthermore, the height  32  of each aerodynamic protrusion  14  can be independent of the height  32  of other aerodynamic protrusions  14  along the spoke  18 . Preferably, the height  32  of all aerodynamic protrusions  14  is the same. 
     In operation, when applying these percentages to the spoke  18  and aerodynamic protrusions  14  described a calculation may, optionally, be applied. For example, The Journal of Aircraft article (David S. Miklosovic, Mark M. Murray, &amp; Laurens E. Howle,  Experimental Evaluation of Sinusoidal Leading Edges,  Journal of Aircraft, Vol. 44, No. 4, 1404-1407, (2007)) provides an equation which is used, for example, to calculate the width of the spoke  18  (x) at any given point (y) along the leading edge  24  of the scalloped aerodynamic protrusions  14  based on the chord  34 ( c ). 
         x   LE =0.04 c *cos(2π y/ 0.41 c ) 
     As stated above, preferably, the scallop-shaped aerodynamic protrusions  14  repeat sinusoidally, so in the equation the cosine function is used. The term 0.41c represents the period of the wave, which is the length of each aerodynamic protrusion  14 . The term 0.04c represents the amplitude of the wave, which is the height  32  of each aerodynamic protrusion  14 . The symbol c represents the chord  34  of the spoke  18 , from leading edge  24  to the trailing edge  26 . 
     Applying the preferred dimensions to the spoke  18  as described above, to the equation, the height  32  of each aerodynamic protrusion  14  is 0.04* chord  34 , or 0.04*3 inches=0.12 inches. The width  30  or period of each protrusion  14  is 0.41*chord  34 , or 0.41*3 inches=1.23 inches. At the preferred spoke  18  length, about 7 inches, would have: 7/1.23=5.69 aerodynamic protrusions  14 . Only whole aerodynamic protrusions  14  would be used. Therefore, this embodiment would have 5 aerodynamic protrusions  14 . 
       FIG. 4  illustrates a side plan view illustrating a spoke  18 , with aerodynamic protrusions  14  formed in accordance with the present invention. 
       FIGS. 5A and 5B  illustrate various alternative shapes suitable for the aerodynamic protrusions  14 . The aerodynamic protrusions  14  can be any shape that will provide the desired effect. For example, the aerodynamic protrusions  14  can be circular, spherical, conical, triangular, cube-shaped, rectangular, rhomboid, wave-like, scallop-shaped, etc. Any combination of shapes can also be used. Preferably the aerodynamic protrusions  14  form a scallop-shaped surface along the leading edge of the spoke. 
       FIGS. 6A and 6B  illustrate of various alternative configurations for the aerodynamic protrusions  14  along the spoke  18 . The camber of the aerodynamic protrusions  14  can be consistent across the spoke  18  or can vary, for example, increasing camber toward the hub  16  or decreasing camber from the hub  16 . Another pattern, for example, would be for the camber to decrease until the midpoint of the spoke  18  and then increase camber toward the hub  16  and the rim  12  or the camber can increase until the midpoint and decrease toward the hub  16  and the rim  12 . Preferably, the aerodynamic protrusions  14  and the associated valleys  15  are uniform in camber along the length of the spoke  18 . Most preferably the aerodynamic protrusions  14  create an undulating curve along the length of the spoke  18 . 
     While primarily directed to racing bicycle wheels, in operation the wheel  10  can be utilized on bicycles, for example: adult bicycles, children&#39;s bicycles, bicycle training wheels, tandem bicycles, recumbent bicycles, lowriders, half bicycles, racing bicycles, dirt bikes, unicycles, tricycles, quadracycles, mountain bikes, touring bicycles, cruiser bicycles, velocipedes, and any other type of bicycle. The wheel can also be used, for example, on motor bikes, wheelchairs, racing wheelchairs, or motorcycles. Although the wheels  10  of the invention may be replace only one wheel of a bicycle, preferably, the wheels  10  of replace all currently used wheels of the bicycle. 
     While there have been described what are presently believed to be the preferred embodiments of the invention, those skilled in the art will appreciate that further changes and modifications can be made to the present invention, and it is intended to include such changes and modifications as coming within the scope of the invention.