Abstract:
A protective device adapted to be attached to a bicycle for protecting a rear derailleur includes a mounting member structured for attachment to the bicycle in close proximity to the rear derailleur. A shock absorbing member extends from the mounting member and is dimensioned so as to be positioned between the bicycle frame and the rear derailleur.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention is directed to bicycles and, more particularly, to a protective device for attachment to a bicycle for protecting a rear derailleur.  
           [0002]    A typical bicycle has a frame comprising a head tube that rotatably supports a front fork and handlebar assembly, a top tube extending rearwardly from the head tube, a down tube extending downwardly at an angle from the head tube, a generally vertical seat tube having an upper portion connected to the rear end of the top tube, a bottom bracket connecting the lower portion of the seat tube and the rear end of the down tube, a pair of seatstays (tubes) extending rearwardly and downwardly from the upper portion of the seat tube, a pair of chainstays (tubes) extending rearwardly from the bottom bracket, and a pair of dropout members, each dropout member connecting the rear end of a seatstay to the rear end of a corresponding chainstay. A front wheel is rotatably supported by the front fork through a front wheel axle, and a rear wheel is rotatably mounted to the pair of dropout members through a rear wheel axle. Left and right of crank arms, each supporting a pedal, are attached to opposite ends of a crank axle which, in turn, is rotatably supported within the bottom bracket. Multiple front sprockets usually are mounted to the right crank arm coaxially with the crank axle, and multiple rear sprockets are mounted coaxially with and rotate with the rear wheel. A chain engages one of the front sprockets and one of the rear sprockets so that the rear wheel is driven in response to rotation of the crank arms. A front derailleur moves the chain among the plurality of front sprockets, and a rear derailleur moves the chain among the plurality of rear sprockets.  
           [0003]    The rear derailleur often is rotatably mounted to the dropout member in close proximity to the rear sprockets. A spring typically biases the rear derailleur in a clockwise direction when viewed from the right side of the bicycle, and the actual rotational position of the rear derailleur changes depending on which front and rear sprockets are engaged by the chain. During vigorous riding over rough terrain, jarring motion can cause the derailleur to rotate counterclockwise and strike the nearby chainstay. This causes undesirable noise and risks damage to the derailleur.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is directed to a protective device adapted to be attached to a bicycle for protecting a rear derailleur. In one embodiment of the present invention, a mounting member is structured for attachment to the bicycle in close proximity to the rear derailleur. A shock absorbing member extends from the mounting member and is dimensioned so as to be positioned between the bicycle frame and the rear derailleur. When riding over rough terrain, the rear derailleur will strike the shock absorbing member rather than the chainstay, thus eliminating risk of damage to the rear derailleur.  
           [0005]    The protective device may take many different forms. For example, and not to be limited thereto, the protective device may comprise an upper wall for positioning at an upper surface of the bicycle frame, a first side wall for positioning at a first side surface of the bicycle frame, and a shock absorbing member attached to the first side wall in some manner. If desired, the shock absorbing member may define an opening, and a fastener may extend through the opening for attaching the shock absorbing member to the first side wall. If the mounting member has a second side wall, then the shock absorbing member may be disposed between the first side wall and the second side wall, likewise with or without a fastener. The mounting member may include a bottom wall structured for positioning beneath a bottom surface of the bicycle frame, wherein the shock absorbing member is attached to the bottom wall in any suitable manner. If desired, the shock absorbing member may define an opening, wherein the bottom wall extends through the opening. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a side view of a rear portion of a bicycle illustrating a particular embodiment of a protective device according to the present invention for a bicycle rear derailleur;  
         [0007]    [0007]FIG. 2 is a view taken along line II-II in FIG. 1;  
         [0008]    [0008]FIG. 3 is a view taken along line III-III in FIG. 1; and  
         [0009]    FIGS.  4 - 7  are views taken along line III-III in FIG. 1 showing alternative embodiments of a protective device according to the present invention for a bicycle rear derailleur.  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0010]    [0010]FIG. 1 is a side view of a rear portion of a bicycle  10  illustrating a particular embodiment of a protective device  14  according to the present invention. As shown in FIG. 1, bicycle  10  includes a chainstay  18  connected to a seatstay  22  through a dropout member  26 . As is well known, the illustrated chainstay  18 , seatstay  22  and dropout member  26  are one of a pair of such members that rotatably support a rear wheel (not shown) through an axle  30 . A base member  34  of a rear derailleur  38  is rotatably mounted to dropout member  26  through a pivot shaft  42  in a known manner. Link members  46  and  50  are pivotably mounted to base member  34  through pivot pins  51  and  52 , respectively, and to a movable member  54  through pivot pins  55  and  56 , respectively. A chain guide  58  is pivotably mounted to movable member  54  through a pivot shaft (not shown). Chain guide  58  includes a guide pulley  62  and a tension pulley  66  for guiding a chain  70  among a plurality of rear sprockets  74  (shown schematically). A coil spring (not shown) typically is mounted around pivot shaft  42  for biasing base member  34  in a clockwise direction, and another coil spring (not shown) typically is mounted around the pivot shaft connecting chain guide  58  to movable member  54  for biasing chain guide  58  in a clockwise direction.  
         [0011]    Protective device  14  comprises an elongated mounting member  80  with a first end  84  and a second end  88 . A shock absorbing member  92  extends downwardly from the first end  84  of mounting member  80  and is dimensioned so as to be positioned between movable member  54  and/or chain guide  58  and chainstay  18 . A chain guard  96  extends upwardly from the second end  88  of mounting member  80 .  
         [0012]    In this embodiment, chain guard  96  prevents chain  70  from contacting the rear wheel  100  (FIG. 2) in a manner shown in U.S. Pat. No. 4,786,071. As shown in FIG. 2, mounting member  80  has a curved upper wall  104  for attaching to the curved upper surface  108  of chainstay  18  through an adhesive or some other means. Chain guard  96  extends upwardly and inwardly at an incline toward rear wheel  100 , and it includes a chain guide surface  112  that is typically located laterally inwardly and below chain  70  when protective device  14  is attached to chainstay  18 . Chain guide surface  112  deflects chain  70  outwardly whenever chain  70  moves inwardly and/or downwardly to prevent chain  70  from being caught by rear wheel  100 .  
         [0013]    [0013]FIG. 3 is a view taken along line III-III in FIG. 1. As shown in FIG. 3, upper wall  104  of mounting member  80  at first end  84  is positioned at the upper (e.g., top) surface  108  of chainstay  18 , a side wall  112  of mounting member  80  is positioned at a side surface  116  of chainstay  18 , and a bottom wall  120  of mounting member  80  is positioned below a bottom surface  124  of chainstay  18 . In this embodiment, chain guard  96 , upper wall  104 , side wall  112  and bottom wall  120  of mounting member  80  are formed as one piece from a material such as a synthetic resin or a metal plate, but of course the various structures may be formed by separate components and from different materials attached or bonded together by any suitable means.  
         [0014]    In this embodiment, shock absorbing member  92  has a substantially completely solid cross section, and it includes an upper portion  130  attached to bottom wall  120  through an adhesive or some other means, an intermediate portion  134  disposed below the upper portion  130 , and a lower portion  138  disposed below the intermediate portion  134 . Intermediate portion  134  has a width W 1  less than a width W 2  of the upper portion  130  and a width W 3  of the lower portion  138 . Shock absorbing member  92  may comprise a resilient material such as rubber or some other material capable of absorbing forces from movable member  54  and/or chain guide  58 . In general, shock absorbing member  92  may be a unitary structure or a structure formed from multiple components that move in such a manner to absorb forces from rear derailleur  38 . Such forces could be absorbed by compression, deflection, telescoping and so on, whether or not the original shape of shock absorbing member  92  is restored after the shock is absorbed, and even by destruction of shock absorbing member  92 . The decreased width of intermediate portion  134  facilitates compression and deflection in this embodiment.  
         [0015]    [0015]FIG. 4 is a view taken along line III-III in FIG. 1 showing a protective device  14   a  that represents an alternative embodiment of the present invention. In this embodiment, first end  84   a  includes an upper wall  150  positioned at the upper surface  108  of chainstay  18  and a side wall  154  positioned at the side surface  116  of chainstay  18 . A shock absorbing member  158  is disposed at a lower portion  154   a  of side wall  154  such that upper wall  150 , side wall  154  and shock absorbing member  158  are formed as one piece from the same material such as rubber. Of course, shock absorbing member  158  may be a separate component attached to side wall  154  by an adhesive or by some other suitable manner, and it may be formed from a material different from the other components as in the first embodiment. As in the first embodiment, shock absorbing member  158  includes an upper portion  162 , an intermediate portion  166  disposed below the upper portion  162 , and a lower portion  170  disposed below the intermediate portion  166 . Intermediate portion  166  also has a width W 1  less than a width W 2  of the upper portion  162  and a width W 3  of the lower portion  170 . However, in this embodiment, upper portion  162  has a hollow portion  174 , and lower portion  170  has a hollow portion  178  to give shock absorbing member  158  the shape of a FIG. 8. These hollow portions  174  and  178  further facilitate compression of shock absorbing member  158 .  
         [0016]    [0016]FIG. 5 is a view taken along line III-III in FIG. 1 showing a protective device  14   b  that represents another alternative embodiment of the present invention. In this embodiment, first end  84   b  includes an upper wall  180  positioned at the upper surface  108  of chainstay  18 , an upper side wall  184  positioned at the side surface  116  of chainstay  18 , a bottom wall  188  positioned below the bottom surface  124  of chainstay  18 , a lower side wall  192  extending downwardly from the left edge  196  of bottom wall  188 , a lower side wall  200  extending downwardly from the right edge  204  of bottom wall  188 , and retaining projections  208  and  212  extending towards each other from the bottom edges  216  and  220  of lower side walls  192  and  200 , respectively. A shock absorbing member  224  formed of rubber or some other resilient material having the overall shape of a square has retaining grooves  228  and  232  that engage retaining projections  208  and  212 , respectively, so that shock absorbing member is retained to bottom wall  188  and lower side walls  192  and  200 .  
         [0017]    [0017]FIG. 6 is a view taken along line III-III in FIG. 1 showing a protective device  14   c  that represents another alternative embodiment of the present invention. In this embodiment, first end  84   c  includes an upper wall  220  positioned at the upper surface  108  of chainstay  18 , a side wall  224  positioned at the side surface  116  of chainstay  18 , and a side wall  228  positioned at a side surface  118  of chainstay  18 . A portion  224   a  of side wall  224  having an opening  232  and a portion  228   a  of side wall  228  having an opening  236  both extend below the bottom surface  124  of chainstay  18 . A shock absorbing member  240  formed of rubber or some other resilient material having the shape of a rectangle is disposed between portions  224   a  and  228   a.  Shock absorbing member  240  has an opening  244  that aligns with openings  232  and  236  so that a fastener such as a screw  248  can extend through openings  232 ,  236  and  244  and mesh with a nut  252  to retain shock absorbing member  240  to side walls  224  and  228 .  
         [0018]    [0018]FIG. 7 is a view taken along line III-III in FIG. 1 showing a protective device  14   d  that represents another alternative embodiment of the present invention. In this embodiment, mounting member  80  does not have an elongated shape, and chain guard  96  is omitted. Instead, mounting member  80  includes an upper wall  270  positioned at the upper surface  108  of chainstay  18 , a side wall  274  comprising side wall sections  274   a  and  274   b  connected together by a connector  278  and positioned at the side surface  116  of chainstay  18 , a side wall  282  positioned at the side surface  118  of chainstay  18 , and a bottom wall  286  positioned below bottom surface  124  of chainstay  18 . A shock absorbing member  290  formed of rubber or some other resilient material having the shape of a rectangle is disposed below bottom surface  124  of chainstay  18 . Bottom wall  286  extends through an opening  294  in shock absorbing member  290  to retain shock absorbing member  290  to bottom surface  124  of chainstay  18 . Mounting member  80  may be formed very simply from a zip tie.  
         [0019]    While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. For example, the size, shape, location or orientation of the various components may be changed as desired. Mounting member  80  may be attached to dropout member  26  or be positioned in any convenient manner that accomplishes a desired shock absorbing function. Components that are shown directly connected or contacting each other may be spaced apart or may have intermediate structures disposed between them. The functions of one element may be performed by two, and vice versa. The structures and functions of one embodiment may be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature that is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the scope of the invention should not be limited by the specific structures disclosed or the apparent initial focus on a particular structure or feature.