Patent Abstract:
A chain ring protector having a substantially planar mounting bracket operably secured to the bottom bracket sleeve of a vehicle with a durable semi-circumferential guard extending therefrom is disclosed. The durable guard has a substantially arcuate outer edge sized to approximate the outer diameter of a chain ring, and it is operably secured to the planar mounting bracket such that the outer edge extends slightly beyond the outer diameter of the portion of the chain ring extending below the bottom bracket sleeve.

Full Description:
Application Ser. No. 12/017,425 is a reissue of application Ser. No. 10/236,766, which has a U.S. Pat. No. 7,066,856.  
     FIELD OF THE INVENTION 
     The present invention relates to a protector for chain rings on bicycles and the like. In particular, it includes a mounting bracket operably secured to the bottom bracket sleeve with a durable guard extending therefrom and detachably secured thereto. 
     BACKGROUND OF THE INVENTION 
     Wheeled vehicles and especially in-line, two-wheeled vehicles such as bicycles, motorcycles, scooters, and the like, are popular forms of transportation, exercise, and sport. More recently, such vehicles are being used in particularly rugged environments including operating over unimproved roads and rough terrain, and for stunt riding over stairs and the like. For example, a form of bicycle commonly known as a mountain bike is specifically intended for off-road operation. 
     Most two-wheeled vehicles are propelled by a chain operably extending between two or more sprockets. One sprocket, commonly known as a chain ring, is driven by a power source such as a crank and pedal assembly. In bicycles, the chain ring is operably secured to a lower hub of the bicycle&#39;s frame which is commonly known as the lower bracket sleeve. The crank and pedal assembly usually have an axis of rotation centered along a centerline extending through the lower bracket sleeve. 
     Chain rings are usually planar disks with teeth along their outer diameter for engaging the chain. In order for the chain ring to operate effectively, it must remain substantially planar and the teeth must remain intact during operation of the vehicle. However, portions of most chain rings remain exposed and extend below the bicycle frame. Accordingly, chain rings are susceptible to bending and damage caused by inadvertent impact with objects. 
     This susceptibility is increased with off-road and stunt riding of the vehicle. For example, a rider of a mountain bicycle may frequently attempt to jump small objects such as rocks and fallen trees. If the rider executes a jump and in the process lands the bicycle such that a large rock straddles the front and rear wheels, the chain ring can impact the rock causing damage to the chain ring. 
     Attempts to protect the chain ring from inadvertent impacts have had limited success. For example, U.S. Pat. No. 5,320,583 to van Wingen born Looyen teaches securing a circular disk to the exterior planar surface of a chain ring such that the circular disk and chain ring are substantially parallel to each other and rotatable on the same axis or rotation. As a rider pedals, the chain ring and circular disk rotate about the axis of rotation. The circular disk contacts some objects approaching the chain ring first, thereby protecting the chain ring to a certain degree. However, since the circular disk is directly connected to the chain ring and drive shaft, any bending or damage of the circular disk caused by the impact will likely also bend the attached chain ring or drive shaft. Moreover, such circular disks offer negligible protection from impacts to the chain ring arising from contact with objects positioned toward the inside surface of the chain ring. 
     Inventors have also attempted to extend a chain ring protector directly from the bicycle&#39;s frame. For example, U.S. Pat. No. 5,067,930 to Morales teaches extending a trough-type protector from forward and aft struts mounted to the frame. The curved trough-type protector extends below the chain ring, thereby protecting it from inadvertent impact. A first clamp for securing the forward strut is positioned on a rail of the frame extending forward from the mounting bracket sleeve. A second clamp for securing the aft strut is positioned on rear wheel forks extending rearward from the mounting bracket sleeve. In an effort to allow the through-type protector to accommodate different bicycle designs, a swivel is provided between the first clamp and front strut. 
     Despite the benefits of the Morales design, it has several drawbacks. For example, a large amount of hardware, such as the first and second clamps, pivot structure, and struts, is required to support the protector, thereby increasing the expense of the structure and time required to mount and align it properly. Similarly, not all bicycles have the frame structure stemming from the mounting bracket sleeve as shown in Morales. Accordingly, the first and second clamps and orientation taught in Morales may not be operable when attempting to install the Morales protector on these different frame structures. 
     In addition, the length of the struts determines the size of the chain ring that may be used with it. Despite the limited adjustability provided by the swivel, if the struts are too short, a trough-type protector will not extend below the chain ring. Also, if the struts are too long, the trough-type protector can interfere with operation of the bicycle. In addition, under some impacts on the trough-type protector, the swivel structure can actually allow the trough-type protector to deflect into to the chain ring, thereby damaging it, or at least forcing the rider to stop to realign the protector. 
     SUMMARY OF THE INVENTION 
     Accordingly, despite the benefits of the known chain ring protectors, there remains a need for a simple, cost effective, easy to install and adjust, chain ring protector that can be operably secured to a large number of vehicles independent of a particular frame design, and that can effectively protect any sized chain ring operably installed on a vehicle without interfering with operation of the vehicle. In addition to other benefits that will become apparent in the following disclosure, the present invention fulfills these needs. 
     The present invention is a substantially planar mounting bracket operably secured to the bottom bracket sleeve of a vehicle with a durable guard extending therefrom. The durable guard has a substantially arcuate outer edge sized to approximate the outer diameter of a chain ring, and it is operably secured to the planar mounting bracket such that the outer edge extends slightly beyond the outer diameter of the chain ring in which it is protecting. 
     Preferably, the durable guard is detachably secured to the mounting bracket, and the mounting bracket includes a plurality of mounting portions thereon, thereby allowing a large variety of possible mounting configurations for the durable guard. More preferably, the guard includes parallelly aligned slots extending therethrough for operably engaging the mounting portions, thereby allowing the outer edge of the durable guard to be adjusted simply by sliding the durable guard along the slots toward or away from the bottom bracket sleeve. 
     Since the durable guard is detachably secured to the mounting bracket, the durable guard may be replaced easily if it becomes damaged or worn, or if a different sized durable guard is desired. 
     In an alternative embodiment, a second chain ring protector can be installed on the opposite side of the bottom bracket sleeve, and the two chain ring protectors can be operably secured together with a stabilizing bracket extending therebetween. 
     Additional objects and advantages of the present invention will be apparent from the detailed description of the preferred embodiment thereof, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric front, right view of a bicycle having a chain ring protector installed thereon in accordance with an embodiment of the present invention. 
         FIG. 2  is an enlarged, fragmentary, exploded, isometric view of the chain ring protector shown in  FIG. 1 . 
         FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a side view of the chain ring protector showing a possible orientation with respect to a chain ring. 
         FIG. 5A  is a first sectional view of an alternative configuration showing a possible use of two chain ring protectors in accordance with an alternative embodiment of the present invention. 
         FIG. 5B  is a second sectional view of the alternative configuration of  FIG. 5A . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A simple, cost effective, easy to install and adjust, chain ring protector  10  operably secured to the lower bracket sleeve  12  of a vehicle, such as a bicycle  14 , is shown in  FIGS. 1-5B . 
     Referring to  FIG. 1 , the bicycle  14  includes a frame  16  having a front wheel  18 , back wheel  20 , handle bars  22 , seat  24 , and the lower bracket sleeve  12  operably secured thereto. Preferably, the lower bracket sleeve  12  is reverse threaded to accept the threads of a conventional lower bracket spindle  26  ( FIG. 2 ) therethrough. The lower bracket spindle  26  is a common, commercially available product, and includes a shaft  28  operably received within a housing  30 . The shaft  28  rotates about a longitudinal centerline  32 . Usually, bearings (not shown) are sealed within the housing  30  to facilitate rotation of the shaft  28 . 
     Preferably, the housing  30  includes the reverse threads  34  toward one end  36  with a lip  38  adjacent to those threads  34 . More preferably, the housing  30  also includes a recess  40  and spaced-apart notches  42  to allow a mating wrench portion (not shown) to be detachably secured thereto. According, the mating wrench portion may be used to tighten and loosen the lower bracket spindle  26  to the lower bracket sleeve  12 . 
     Left and right cranks  44 ,  46 , respectively, are operably secured to the ends  48 a,  48 b of the lower bracket spindle shaft  28  with a pivoting pedal  50  secured at the opposite ends of each crank  44 ,  46 . At least one sprocket having teeth  52  extending radially therefrom is secured to the lower bracket spindle and positioned on one side of the lower bracket sleeve  12 . This sprocket is also commonly known as a chain ring  54 . Usually, the chain ring  54  is also secured to one of the cranks  44 ,  46 . 
     A continuous loop chain (not shown) encircles the chain ring  54  and operably engages the teeth  52  of the chain ring  54 . The chain also engages a second sprocket (not shown) operably secured to one of the front and rear wheels of the bicycle  14 . Accordingly, when an operator pedals the bicycle by alternatingly urging the left and right cranks  44 ,  46 , respectively, to spin the shaft  28 , the chain ring  54  urges the chain to spin one of the wheels of the bicycle. 
     As best shown in  FIGS. 2 and 3 , the chain ring protector  10  is operably secured to the lower bracket sleeve  12 . For example, the chain ring protector  10  can include a substantially planar mounting bracket  60  with an impact resistant and durable guard  62  extending therefrom. The mounting bracket  60  includes a central bracket mounting hole  64  for receiving the lower bracket spindle  26  therethrough. It can be appreciated that by tightening the lower bracket spindle  26  on the threads of the lower bracket sleeve  12 , the mounting bracket  60  operates much like a conventional washer and is thereby secured in place when the lip  38  of the lower bracket spindle housing  30  tightens against the mounting bracket  60 . 
     The mounting bracket  60  includes a plurality of guard mounting holes  70 a-i thereon. Preferably, the mounting bracket  60  has two arms  72 ,  74  extending from the central bracket mounting hole  64  and a substantially circular outer edge  76  extending from the central bracket mounting hole  64  opposite the arms  72 ,  74  as best shown in  FIG. 2 . Each of the arms  72 ,  74  has a guard mounting hole  70 a,  70 b, respectively, thereon. Also, a plurality of guard mounting holes  70 c-i are aligned along the circular outer edge  76 . 
     The guard  62  has a substantially planar mounting portion  80  with an opening  82  to prevent it from interfering with the lower bracket spindle  26 . A substantially arcuate outer edge  84  extends radially from the opening  82  as best shown in  FIG. 2 . The mounting portion  80  includes a plurality of mounting slots  86 a-c, which are preferably parallelly aligned and spaced-apart from each other. Each slot  86 a-c is positioned to align with one guard mounting hole  70 a-c on the mounting bracket  60 . For example, slot  86 a aligns with mounting hole  70 a, slot  86 b aligns with mounting hole  70 b, and slot  86 c aligns with mounting hole  70 c. 
     Connectors  90  extend through each aligned mounting hole and slot combination. Preferably, each connector includes a screw  92  being operably received into an internally threaded shaft  94  with a resilient washer  96  operably engaging the guard  62  and a lock washer  98  holding the screw  92  in place. More preferably, the internally threaded shaft  94  has a tapered head  100  and is recessed within the guard mounting hole ( 70 a shown in  FIG. 2 ) when the screw  92  is tightened. 
     Preferably, the mounting slots  86 a-c are aligned to allow the substantially arcuate outer edge  84  to move toward or away from the lower bracket spindle  26  when the guard  62  is mounted to the mounting bracket  60 . As shown in  FIG. 4 , the mounting slots  86 a-c allow the position of the arcuate outer edge  84  of the guard  62  to extend past the outer radius  102  of the chain ring  54 . Moreover, the mounting slots  86 a-c allow the guard  62  to be individually adjusted for any particular chain ring  54  size, without necessarily requiring different guards  62  to protect different sized chain rings  54 . 
     The guard  62  and mounting bracket  60  are constructed of durable, impact resistant materials. One known preferred guard material is Ultra-High Molecular Weight polyethylene or plastic, which is commonly known in the materials industry as “UHMW.” One known acceptable mounting bracket material is aluminum, and more preferably a type of aluminum known as “6061 Aluminum.” 
     As shown in  FIG. 3 , the chain ring protector  10  of the present invention can be used concurrently with a conventional chain ring-mounted protector  106 . In such case, the chain ring protector  10  remains fixed to the lower bracket sleeve  12  to protect the chain ring  54  from impacts arising from contact with objects positioned toward the inside surface of the chain ring  54 . 
     It can be appreciated that a plurality of chain rings  54 a-c ( FIG. 3 ) can be positioned on the lower bracket spindle shaft  28 . In such case, the guard  62  is preferably positioned to extend beyond the outer radius  102  of the largest chain ring  54 c ( FIG. 3 ) on the shaft  28  as shown in  FIG. 3 . 
     Referring to  FIG. 2 , if desired, an anti-rotation mount  110  can be secured to the guard mounting holes  70 d-i on the mounting bracket  60 . The anti-rotation mount  110  extends from the mounting bracket  60  toward the frame  16  and is preferably wedged adjacent to one or two frame members  112  extending from the lower bracket sleeve  12 . Preferably, the anti-rotation mount  110  includes a notched recess  114  sized to operably engage the frame members  112 . The large number of guard mounting holes  70 c-i along the substantially circular outer edge  76  allow the anti-rotation mount  110  to be effectively installed on a wide variety of frame styles and sizes. An installer mounts the anti-rotation mount  110  with bolts  111  extending through one or more of the mounting holes  70 c-i on the mounting bracket  60 . The installer simply selects the particular mounting holes  70 c-i ( FIG. 2  shows mounting holes  70 f and  70 g being used) that best fit that particular frame. 
     When the chain ring protector  10  is installed on the bicycle  14 , the chain ring  54  is protected from inadvertent impacts with an object  11 . The mounting bracket also assists with preventing the chain from inadvertently falling off the chain ring. Moreover, the chain ring protector  10  is operably secured directly to the lower bracket sleeve  12 , one of the strongest elements of the frame  16 . In addition, no portion of the chain ring protector  10  contacts or otherwise engages the chain ring  54  so it will not likely also damage the chain ring  54  in the process of protecting it. Accordingly, should the chain ring protector  10  become damaged during use, it can be easily replaced without removing the mounting bracket  60  from the lower bracket sleeve  12 . Since the chain ring protector is secured primarily in place on the lower bracket sleeve using a conventional lower bracket spindle, which is already needed to enable operation of the bicycle, the need for additional mounting hardware beyond the mounting bracket is greatly reduced over the structure disclosed in U.S. Pat. No. 5,067,930 to Morales. 
     In view of the wide variety of embodiments to which the principles of the invention can be applied, it should be apparent that the detailed embodiments are illustrative only and should not be taken as limiting the scope of the invention. For example, and as best shown in  FIGS. 5A &amp; 5B , two chain rings protectors  10 ,  10 ′ can be installed on a lower bracket sleeve  12 . One chain ring protector  10  is positioned between the lower bracket sleeve  12  and chain ring  54  as previously described. The other chain ring protector  10 ′ is operably secured to the opposite end of the lower bracket sleeve  12  as shown. Preferably, the opposite end of the lower bracket sleeve  12  includes a threaded portion  120  with a mating threaded mount (not shown) having a lip (not shown) for engaging the mounting bracket  60  of the second chain ring protector  10 ′. If desired and as shown in  FIG. 5B , the anti-rotation mount  110  can extend between the two mounting brackets, thereby securing them in place on the bicycle  14 . 
     Accordingly, the claimed invention includes all such modifications as may come within the scope of the following claims and equivalents thereto.

Technology Classification (CPC): 1