Patent Publication Number: US-9415830-B1

Title: Bicycle rim brake

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention generally relates to a bicycle rim brake. More specifically, the present invention relates to a bicycle rim brake that includes a hydraulic actuation device for applying an actuating force to move first and second brake arms to a braking position. 
     2. Background Information 
     Bicycles are typically provided with at least one brake device for stopping. Currently, a wide variety of bicycle brake devices are available. One popular type of bicycle brake device is a rim brake. Rim brakes are configured to apply a braking force to the wheel of a bicycle by pinching the rim of the wheel with a pair of brake shoes attached to a pair of brake arms. Rim brakes are available in several configurations. For example, rim brakes include a side pull type, a center pull type and a dual-pivot. Examples of rim brakes are disclosed in U.S. Pat. No. 7,677,365, which is assigned to Shimano Inc. These rim brakes are operated using a Bowden cable. More recently, hydraulically operated rim brakes have been proposed. 
     SUMMARY 
     Generally, the present disclosure is directed to various features of a bicycle rim brake. In one feature, a bicycle rim brake is provided in which a hydraulic actuation device is provided with two pistons for actuating the brake arms. 
     In view of the state of the known technology and in accordance with a first aspect of the present disclosure, a bicycle rim brake is provided that basically comprises a first brake arm, a second brake arm and a hydraulic actuation device. The first brake arm has a first coupling portion, a first actuated portion and a first mounting portion. The first coupling portion includes a first mounting fastener that is configured to be mounted to a bicycle and that defines a first pivot axis of the first brake arm. The first mounting portion is configured to mount a first friction member and extends from the first coupling portion. The second brake arm has a second coupling portion, a second actuated portion and a second mounting portion. The second coupling portion includes a second mounting fastener that is configured to be mounted to a bicycle and that defines a second pivot axis of the first brake arm. The second mounting portion is configured to mount a second friction member and extends from the second coupling portion. The hydraulic actuation device includes a cylinder housing defining a hydraulic chamber, a first piston movably disposed in the hydraulic chamber and operatively coupled to the first actuated portion of the first brake arm, and a second piston movably disposed in the hydraulic chamber and operatively coupled to the second actuated portion of the second brake arm. 
     In accordance with a second aspect of the present invention, the bicycle rim brake according to the first aspect is configured so that the first actuated portion and the first mounting portion are disposed on opposite sides of the first coupling portion, and the second actuated portion and the second mounting portion are disposed on opposite sides of the second coupling portion. 
     In accordance with a third aspect of the present invention, the bicycle rim brake according to the first aspect is configured so that the hydraulic chamber includes a first chamber having the first piston disposed therein, a second chamber having the second piston disposed therein, and a third chamber provided between the first and second chambers. 
     In accordance with a fourth aspect of the present invention, the bicycle rim brake according to the third aspect is configured so that the third chamber has a smaller diameter than the first and second chambers. 
     In accordance with a fifth aspect of the present invention, the bicycle rim brake according to the first aspect is configured so that the cylinder housing includes an inlet bore fluidly communicating with the hydraulic chamber at a location between the first and second pistons. 
     In accordance with a sixth aspect of the present invention, the bicycle rim brake according to the fifth aspect is configured so that the first and second pistons are movable along an actuation axis of the hydraulic chamber, and the inlet bore has a center longitudinal axis that is perpendicularly arranged with respect to the actuation axis of the hydraulic chamber. 
     In accordance with a seventh aspect of the present invention, the bicycle rim brake according to the first aspect further comprises a first connecting rod having a first end portion connected to the first piston and a second end portion connected to the first actuated portion; and a second connecting rod having a first end portion connected to the second piston and a second end portion connected to the second actuated portion. 
     In accordance with an eighth aspect of the present invention, the bicycle rim brake according to the seventh aspect is configured so that the first end portion of the first connecting rod is configured to be pivotally coupled to the first piston, and the first end portion of the second connecting rod is configured to be pivotally coupled to the second piston. 
     In accordance with a ninth aspect of the present invention, the bicycle rim brake according to the first aspect further comprises a support member coupled to the first and second coupling portions and maintains the first and second pivot axes at a prescribed distance apart from each other. 
     In accordance with a tenth aspect of the present invention, the bicycle rim brake according to the ninth aspect is configured so that the hydraulic actuation device is mounted on the support member. 
     In accordance with an eleventh aspect of the present invention, the bicycle rim brake according to the first aspect further comprises a first return spring biasing the first brake arm about the first pivot axis towards the first piston. 
     In accordance with a twelfth aspect of the present invention, the bicycle rim brake according to the eleventh aspect further comprises a first adjustment member arranged to adjust a biasing force of the first return spring. 
     In accordance with a thirteenth aspect of the present invention, the bicycle rim brake according to the eleventh aspect further comprises a second return spring biasing the second brake arm about the second pivot axis towards the second piston. 
     In accordance with a fourteenth aspect of the present invention, the bicycle rim brake according to the thirteenth aspect further comprises a second adjustment member arranged to adjust a biasing force of the second return spring. 
     Also other objects, features, aspects and advantages of the disclosed bicycle rim brake will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses one embodiment of the bicycle rim brake. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the attached drawings which form a part of this original disclosure: 
         FIG. 1  is a front elevational view of a portion of a bicycle equipped with a bicycle rim brake in accordance with a first embodiment, with the bicycle rim brake being in a non-braking position or resting position; 
         FIG. 2  is a front perspective view of the bicycle rim brake illustrated in  FIG. 1  with the bicycle rim brake being in the non-braking position; 
         FIG. 3  is a rear perspective view of the bicycle rim brake illustrated in  FIGS. 1 and 2  with the bicycle rim brake being in the non-braking position; 
         FIG. 4  is a rear elevational view of the bicycle rim brake illustrated in  FIGS. 1 to 3  with the bicycle rim brake being in the non-braking position; 
         FIG. 5  is a side elevational view of the bicycle rim brake illustrated in  FIGS. 1 to 4  with the bicycle rim brake being in the non-braking position; 
         FIG. 6  is a front elevational view of the bicycle rim brake illustrated in  FIGS. 1 to 5  with a portion of the support member of the bicycle rim brake broken away to reveal the spring arrangement; 
         FIG. 7  is a partially exploded perspective view of the bicycle rim brake illustrated in  FIGS. 1 to 6 ; 
         FIG. 8  is another partially exploded perspective view of selected parts of the bicycle rim brake illustrated in  FIGS. 1 to 6 ; 
         FIG. 9  is another partially exploded perspective view of selected parts of the bicycle rim brake illustrated in  FIGS. 1 to 6  as viewed from the rear side of the bicycle rim brake; 
         FIG. 10  is another partially exploded perspective view of selected parts of the bicycle rim brake illustrated in  FIGS. 1 to 6  as viewed from the front side of the bicycle rim brake; 
         FIG. 11  is a front elevational view of the bicycle rim brake illustrated in  FIGS. 1 to 6  with portions of the hydraulic actuation device shown in longitudinal cross section; 
         FIG. 12  is a cross sectional view of a portion of the hydraulic actuation device of the bicycle rim brake illustrated in  FIGS. 1 to 6  showing one of the sealing members in a non-actuated position; 
         FIG. 13  is a cross sectional view of the portion of the hydraulic actuation device illustrated in  FIG. 12 , but with the piston and the sealing member in actuated positions; 
         FIG. 14  is an enlarged cross sectional profile of a portion of one of the sealing members of the hydraulic actuation device of the bicycle rim brake illustrated in  FIGS. 1 to 6 ; 
         FIG. 15  is a rear elevational view of the bicycle rim brake illustrated in  FIGS. 1 to 6  with the first and second brake arms held in a position for removing the hydraulic actuation device; 
         FIG. 16  is a side elevational view of the support member and the holder of the bicycle rim brake illustrated in  FIGS. 1 to 6  with the cylinder housing of the hydraulic actuation device shown in cross section and the cylinder housing of the hydraulic actuation device partially remove from the holder of the bicycle rim brake; and 
         FIG. 17  is a rear elevational view of the bicycle rim brake illustrated in  FIGS. 1 to 6  with the first and second brake arms held in the position for removing the hydraulic actuation device and the hydraulic actuation device removed from the holder of the bicycle rim brake. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the bicycle field from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     Referring initially to  FIG. 1 , a portion of a bicycle  1  having a front fork  2  is illustrated that is equipped with a bicycle rim brake  12  in accordance with a first embodiment. The bicycle rim brake  12  is installed on the front fork  2  such that the bicycle rim brake  12  straddles a bicycle rim R of a front wheel W. Of course, it will be apparent to those skilled in the bicycle field from this disclosure that the bicycle rim brake  12  can be used in conjunction with a rear bicycle wheel. 
     The bicycle rim brake  12  basically comprises a first brake arm  14 , a second brake arm  16  and a hydraulic actuation device  18 . In the first embodiment, the bicycle rim brake  12  is hydraulically actuated by a conventional hydraulic actuation device (e.g., a brake lever), which is not shown. The bicycle rim brake  12  further comprises a support member  20 . The first and second brake arms  14  and  16  are pivotally supported on the support member  20 . In particular, the first brake arm  14  is pivotally supported on the support member  20  by a first mounting fastener  22  that is configured to be mounted to the front fork  2  of the bicycle  1 . The first mounting fastener  22  defines a first pivot axis P 1  of the first brake arm  14 . Similarly, the second brake arm  16  is pivotally supported on the support member  20  by a second mounting fastener  24  that is configured to be mounted to the front fork  2  of the bicycle  1 . The second mounting fastener  24  defines a second pivot axis P 2  of the first brake arm  14 . 
     As seen from  FIGS. 2, 3 and 6 , the hydraulic actuation device  18  is mounted on the support member  20 . The hydraulic actuation device  18  is fluidly connected to a first end of a hydraulic hose H. The hydraulic hose H further has a second end (not shown) connected to a conventional hydraulic actuating device (not shown). During a braking operation, hydraulic fluid is forced into the hydraulic actuation device  18  causing the hydraulic actuation device  18  to push the first and second brake arms  14  and  16  for applying a braking force to the bicycle rim R. 
     The hydraulic actuation device  18  is operatively coupled between the first and second brake arms  14  and  16 , and arranged to pivot the first and second brake arms  14  and  16  about the first and second pivot axes P 1  and P 2 , respectively. Thus, actuation of the hydraulic actuation device  18  causes the first and second brake arms  14  and  16  to move from a non-braking position or resting position to a braking position or actuated position as the first and second brake arms  14  and  16  pivot about the first and second pivot axes P 1  and P 2 , respectively. The pivotal movements of the first and second brake arms  14  and  16  about the first and second pivot axes P 1  and P 2 , respectively, apply a braking force to the bicycle wheel W by pinching the bicycle rim R of the bicycle wheel W. 
     Now, the first and second brake arms  14  and  16  will be discussed in more detail. The first and second brake arms  14  and  16  are each a rigid member made of a suitable rigid material that is typically used for bicycle brake arms. For example, the first and second brake arms  14  and  16  can be a cold-forged aluminum arm or a carbon fiber reinforced arm. As seen from the view in  FIG. 1 , the first brake arm  14  pivots about the first pivot axis P 1  in a counterclockwise direction to contact the bicycle rim R, while the second brake arm  16  pivots about the second pivot axis P 2  in a clockwise direction to contact the bicycle rim R. Thus, the first brake arm  14  pivots about the first pivot axis P 1  in a clockwise direction to move away from the bicycle rim R, while the second brake arm  16  pivots about the second pivot axis P 2  in a counterclockwise direction to move away from the bicycle rim R. 
     As seen in  FIGS. 3 and 4 , the first brake arm  14  basically has a first coupling portion  14   a , a first actuated portion  14   b  and a first mounting portion  14   c . The first actuated portion  14   b  and the first mounting portion  14   c  are disposed on opposite sides of the first coupling portion  14   a . The first coupling portion  14   a  includes the first mounting fastener  22  that is configured to be mounted to the bicycle  1 . Thus, the first coupling portion  14   a  is configured to pivot about the first pivot axis P 1 . The first actuated portion  14   b  extends from the first coupling portion  14   a , and is operatively coupled to the hydraulic actuation device  18 . The first mounting portion  14   c  extends from the first coupling portion  14   a , and is configured to mount a first friction member  26 . In the first embodiment, as seen in  FIG. 3 , the first mounting portion  14   c  includes a slot (elongated opening) for adjustably attaching the first friction member  26 . In the first embodiment, the first friction member  26  is a conventional brake shoe that is detachably attached to the first mounting portion  14   b  in a conventional manner. Basically, the first friction member  26  includes a brake pad holder  26   a  and a brake pad or shoe  26   b . The brake pad holder  26   a  supports the brake pad  26   b , and is attached in the slot formed in the first mounting portion  14   c  by a mounting bolt  26   c . The brake pad  26   b  of the first friction member  26  contacts one side of the bicycle rim R during a braking operation. 
     Similarly, the second brake arm  16  basically has a second coupling portion  16   a , a second actuated portion  16   b  and a second mounting portion  16   c . The second actuated portion  16   b  and the second mounting portion  16   c  are disposed on opposite sides of the second coupling portion  16   a . The second coupling portion  16   a  includes the second mounting fastener  24  that is configured to be mounted to the bicycle  1 . Thus, the second coupling portion  16   a  is configured to pivot about the second pivot axis P 2 . The second mounting portion  16   c  extends from the second coupling portion  16   a , and is configured to mount a second friction member  28 . In the first embodiment, as seen in  FIG. 2 , the second mounting portion  16   c  includes a slot (elongated opening) for adjustably attaching the second friction member  28 . In the first embodiment, the second friction member  28  is a conventional brake shoe that is detachably attached to the second mounting portion  16   b  in a conventional manner. Basically, the second friction member  28  includes a brake pad holder  28   a  and a brake pad or shoe  28   b . The brake pad holder  28   a  supports the brake pad  28   b , and is attached in a slot formed in the second mounting portion  16   c  by a mounting bolt  28   c . The brake pad  28   b  of the second friction member  28  contacts the other side of the bicycle rim R during a braking operation. 
     In the first embodiment, each of the first coupling portion  14   a  and the second coupling portion  16   a  is preferably provided with a bushing and/or bearing structure for pivotally supporting the first and second brake arms  14  and  16  on the first and second fasteners  22  and  24 . Here, the first coupling portion  14   a  further includes a first brake arm supporting unit  30  for rotatably supporting the first brake arm  14  on the first fastener  22 . Similarly, the second coupling portion  16   a  further includes a second brake arm supporting unit  32  for rotatably supporting the second brake arm  16  on the second fastener  24 . In the first embodiment, the first and second brake arm supporting units  30  and  32  are each constructed as disclosed in U.S. Patent Application Publication No. 2013-0341129, which is assigned to Shimano, Inc. 
     Referring to  FIGS. 5, 6 and 8 , the first and second brake arms  14  and  16  are each biased to their non-braking positions, which constitute resting positions of the first and second brake arms  14  and  16 . In more detail, the bicycle rim brake  12  comprises a first return spring  34  and a second return spring  36 . The first return spring  34  biases the first brake arm  14  about the first pivot axis P 1  towards the non-braking position. The second return spring  36  biases the second brake arm  16  about the second pivot axis P 2  towards the non-braking position. The first return spring  34  has a first end portion  34   a  and a second end portion  34   b . The first end portion  34   a  of the first return spring  34  is mounted in an opening in the first brake arm  14 , while the second end portion  34   b  is hooked onto the support member  20 . Similarly, the second return spring  36  has a first end portion  36   a  and a second end portion  36   b . The first end portion  36   a  of the second return spring  36  is mounted in an opening in the second brake arm  16 , while the second end portion  36   b  is hooked onto the support member  20 . 
     Still referring to  FIGS. 5, 6 and 8 , the support member  20  includes a cross member  40 . The cross member  40  of the support member  20  is coupled to the first and second coupling portions  14   a  and  16   a , and maintains the first and second pivot axes P 1  and P 2  at a prescribed distance D apart from each other as seen in  FIG. 6 . The cross member  40  has a first opening  40   a  for receiving the first mounting fastener  22  therethrough, and a second opening  40   b  for receiving the second mounting fastener  24  therethrough. 
     The support member  20  further includes a holder  42 . The holder  42  is supported on the rear side of the cross member  40 . Here, a screw  44  is provided to attach the holder  42  to the cross member  40 . The cross member  40  and the holder  42  are each a rigid member that is made of a suitable rigid material such that as aluminum or carbon fiber. In the first embodiment, the cross member  40  and the holder  42  are separate pieces. However, the cross member  40  and the holder  42  can be formed as a one-piece member of a single unitary material. 
     As explained below, the holder  42  is configured to support the hydraulic actuation device  18  on the first and second brake arms  14  and  16  via the cross member  40  with a toolless connection so that the hydraulic actuation device  18  can be removed and reinstalled from the holder  42 . In this way, the hydraulic actuation device  18  can be removed from the holder  42  and then reinstalled without detaching the first and second brake arms  14  and  16  from the front fork  2 . 
     As seen in  FIGS. 6 and 8 , a mounting boss  46  extends from the rear side of the cross member  40  into a mounting opening  42   a  of the holder  42 . The mounting boss  46  has a threaded bore  46   a . The screw  44  is screwed into the threaded bore  46   a  for attaching the holder  42  to the cross member  40 . Also an anti-rotation protrusion  48  extends from the rear side of the cross member  40  and engages an anti-rotation opening  42   b  of the holder  42 . The holder  42  includes a recess  42   c  that receives the hydraulic actuation device  18 . As explained below, the hydraulic actuation device  18  is snap-fitted into and out of the recess  42   c  for installing and detaching the hydraulic actuation device  18  with respect the first and second brake arms  14  and  16 . 
     As seen in  FIGS. 6 and 8 , the rear side of the cross member  40  has a first spring attachment projection  50  and a second spring attachment projection  52 . The first spring attachment projection  50  is a headed pin for attaching the second end portion  34   b  of the first return spring  34 . In the first embodiment, the biasing forces of the first and second return springs  34  and  36  are adjustable. Specifically, the first spring attachment projection  50  is provided with a threaded hole  50   a . The threaded hole  50   a  threadedly receives a first adjustment member  54  that is arranged to adjust a biasing force of the first return spring  34 . The second spring attachment projection  52  is a headed pin for attaching the second end portion  36   b  of the second return spring  36 . The second spring attachment projection  52  is provided with a threaded hole  52   a . The threaded hole  52   a  threadedly receives a second adjustment member  56  that is arranged to adjust a biasing force of the second return spring  38  independently of the first adjustment member  54 . In the first embodiment, the first and second adjustment members  54  and  56  are set screws. By independently screwing in or unscrewing the first and second adjustment members  54  and  56  a user can independently adjust the biasing forces of the first and second return springs  34  and  36 . However, the first and second adjustment members  54  and  56  can have other configurations such as cams that independently rotate on the first and second spring attachment projections  50  and  52  for change the position of the first and second end portions  34   b  and  36   b  of the first and second return springs  34  and  36 . 
     Now, the hydraulic actuation device  18  will be described in more detail. Basically, the hydraulic actuation device  18  is supported on the support member  20 , and is operatively coupled to the first and second actuated portions  14   b  and  16   b  of the first and second brake arms  14  and  16 . The hydraulic hose H is connected between a conventional hydraulic actuating device (e.g., a brake lever), which is not shown, and the hydraulic actuation device  18 . The hydraulic hose H supplies hydraulic fluid to the hydraulic actuation device  18  in response to operation of the conventional hydraulic actuating device (e.g., a brake lever). 
     As seen in  FIG. 11 , the hydraulic actuation device  18  includes a cylinder housing  60 , a first piston  61  and a second piston  62 . The cylinder housing  60  defines a hydraulic chamber  64 . The first piston  61  is movably disposed in the hydraulic chamber  64 . The hydraulic chamber  64  includes a first chamber  64   a , a second chamber  64   b  and a third chamber  64   c . The first chamber  64   a  has the first piston  61  disposed therein. The second chamber  64   b  has the second piston  62  disposed therein. The third chamber  64   c  is provided between the first and second chambers  64   a  and  64   b . The third chamber  64   c  has smaller diameter than the first and second chambers  64   a  and  64   b . With this arrangement, the hydraulic hose H supplies hydraulic fluid to the third chamber  64   c  to simultaneously actuate the first and second pistons  61  and  62 . 
     The exterior dimensions of the cylinder housing  60  are such that the cylinder housing  60  snaps into and out of the recess  42   c  of the holder  42 . In this way, the hydraulic actuation device  18  can be removed and reinstalled with respect to the first and second brake arms  14  and  16  without a tool. In particular, the holder  42  is configured to have elasticity such that the cylinder housing  60  is snap-fitted into the recess of the holder  42 . In other words, the exterior of the cylinder housing  60  is dimensioned slightly larger than the opening of the recess  42   c  of the holder  42 . As a result, the holder  42  elastically deformed as the cylinder housing  60  of the hydraulic actuation device  18  is push into the recess  42   c  of the holder  42  or pulled out of the recess  42   c  of the holder  42 . In this way, the recess  42   c  of the holder  42  receives the cylinder housing  60  of the hydraulic actuation device  18 , and is retained in the recess  42   c  of the holder  42 . 
     The first piston  61  is movably disposed in the hydraulic chamber  64 . The first piston  61  is operatively coupled to the first actuated portion  14   b  of the first brake arm  14 . In particular, the hydraulic actuation device  18  includes a first connecting rod  66  that connects the first actuated portion  14   b  of the first brake arm  14  to the first piston  61 . Thus, the first actuated portion  14   b  of the first brake arm  14  is operatively coupled to the first piston  61  via the first connecting rod  66 . The second piston  62  is movably disposed in the hydraulic chamber  64 . The second piston  62  is operatively coupled to the second actuated portion  16   b  of the second brake arm  16 . In particular, the hydraulic actuation device  18  includes a second connecting rod  68  that connects the first actuated portion  16   b  of the second brake arm  16  to the second piston  62 . Thus, the second actuated portion  16   b  of the second brake arm  16  is operatively coupled to the second piston  62  via the second connecting rod  68 . 
     As mentioned above, the first return spring  34  biases the first brake arm  14  about the first pivot axis P 1  towards the first piston  61 . Thus, the first connecting rod  66  applies a pushing force on the first piston  61  as a result of the biasing force of the first return spring  30  acting on the first brake arm  14 . As also mentioned above, the second return spring  36  biases the second brake arm  16  about the second pivot axis P 2  towards the second piston  62 . Thus, the second connecting rod  68  applies a pushing force on the second piston  62  as a result of the biasing force of the second return spring  32  acting on the second brake arm  16 . 
     As seen in  FIGS. 9 to 11 , the first connecting rod  66  has a first end portion  66   a  that is connected to the first piston  61  and a second end portion  66   b  that is connected to the first actuated portion  14   b . The first end portion  66   a  of the first connecting rod  66  is configured to be pivotally and detachably coupled to the first piston  61 . In the first embodiment, the first end portion  66   a  of the first connecting rod  66  includes a partially spherical part or ball that is received in a recess or socket  61   a  of the first piston  61 . The first connecting rod  66  is pivotally connected to the first brake arm  14 . The first connecting rod  66  includes a first pivot pin  70  that is disposed in a first socket  14   b   1  of the first actuated portion  14   b  of the first brake arm  14 . The first connecting rod  66  is adjustably connected to the first brake arm  14 . In the first embodiment, the second end portion  66   b  of the first connecting rod  66  is threaded. The second end portion  66   b  is screwed into a threaded hole  70   a  of the first pivot pin  70  for adjustably coupling the first connecting rod  66  to the first brake arm  14 . The end of the second end portion  66   b  has a tool receiving recess for rotating the first connecting rod  66  to adjust the resting position of the first brake arm  14 . In this way, the first connecting rod  66  is configured to remain attached to the first brake arm  14  in a state where the hydraulic actuation device  18  is removed. 
     As seen in  FIGS. 9 to 11 , the second connecting rod  68  has a first end portion  68   a  that is connected to the second piston  62  and a second end portion  68   b  that is connected to the second actuated portion  16   b . The second connecting rod  68  is pivotally connected to the second brake arm  16 . The first end portion  68   a  of the second connecting rod  68  is configured to be pivotally and detachably coupled to the second piston  62 . In the first embodiment, the first end portion  68   a  of the second connecting rod  68  includes a partially spherical part or ball that is received in a recess or socket  61   a  of the second piston  62 . The second connecting rod  68  includes a second pivot pin  72  that is disposed in a second socket  16   b   1  of the second actuated portion  16   b  of the second brake arm  16 . The second connecting rod  68  is adjustably connected to the second brake arm  16 . In the first embodiment, the second end portion  68   b  of the second connecting rod  68  is threaded. The second end portion  68   b  is screwed into a threaded hole  72   a  of the second pivot pin  72  for adjustably coupling the second connecting rod  68  to the second brake arm  16 . The end of the second end portion  68   b  has a tool receiving recess for rotating the second connecting rod  68  to adjust the resting position of the second brake arm  16 . In this way, the second connecting rod  68  is configured to remain attached to the second brake arm  16  in a state where the hydraulic actuation device  18  is removed. 
     As seen in  FIGS. 11 and 16 , the cylinder housing  60  includes an inlet bore  74  fluidly communicating with the hydraulic chamber  64  at a location between the first and second pistons  61  and  62 . In particular, the inlet bore  74  fluidly communicates with the third chamber  64   c  of the hydraulic chamber  64  to supply hydraulic fluid thereto for moving the first and second pistons  61  and  62  within the first and second chamber  64   a  and  64   b  of the hydraulic chamber  64 . The first and second pistons  61  and  62  are movable along an actuation axis A 1  of the hydraulic chamber  64 . The inlet bore  74  has a center longitudinal axis A 2  that is perpendicularly arranged with respect to the actuation axis A 1  of the hydraulic chamber  64 . 
     As seen in  FIGS. 11 to 14 , the hydraulic actuation device  18  includes a first sealing member  81  that is provided on the cylinder housing  60  so as to at least partially support the first piston  61  in the hydraulic chamber  64 . As seen in  FIG. 11 , the hydraulic actuation device  18  includes a second sealing member  82  that is provided on the cylinder housing  60  so as to at least partially support the second piston  62  in the hydraulic chamber  64 . The first and second sealing members  81  and  82  are identical in the first embodiment. The cylinder housing  60  has a first annular recess  60   a  and a second annular recess  60   b . The first sealing member  81  is disposed in the first annular recess  60   a  and protrudes from the first annular recess  60   a  so as to support the first piston  61 . The second sealing member  82  is disposed in the second annular recess  60   b  and protrudes from the second annular recess  60   b  so as to support the second piston  62 . The first and second annular recesses  60   a  and  60   b  are identical, except that they are mirror images in the first embodiment. The first and second annular recesses  60   a  and  60   b  are provided with sufficient axial dimensions so that the first and second sealing members  81  and  82  can deflect in the axial direction along the actuation axis A 1  during movement of the first and second pistons  61  and  62  before contacting the cylinder housing  60 . The first annular recess  60   a  has a trapezoidaly shaped cross-sectional profile which has a first outer surface  60   a   1  that expands in diameter as the first outer surface  60   a   1  approaches toward the first actuated portion  14   b  of the first brake arm  14 . The second annular recess  60   b  has a trapezoidaly shaped cross-sectional profile which has a second outer surface  60   b   1  that expands in diameter as the second outer surface  60   b   1  approaches toward the second actuated portion  16   b  of the second brake arm  16 . Thus, the first and second outer surfaces  60   a   1  and  60   b   1  are angled with respect to the actuation axis A 1  such that the outer diameters of the first and second annular recesses  60   a  and  60   b  increases the farther that the first and second annular recesses  60   a  and  60   b  are from the center longitudinal axis A 2  of the inlet bore  74 . The phrase “trapezoidal shaped cross-sectional profile” as used herein with respect to the first and second annular recesses  60   a  and  60   b  refers to an overall shape of each recess as being trapezoidal with two parallel and two nonparallel sides, and in which the corners can be rounded and/or cutoff at an angle as well as one or more of the sides be non-planar. 
     The first sealing member  81  is made of a flexible, resilient or elastic material such as a rubber material suitable for hydraulic applications. The second sealing member  82  is made of an elastic material that is the same as the first sealing member  81 . The first and second sealing members  81  and  82  create seals between the cylinder housing  60  and the first and second pistons  61  and  62  to prevent hydraulic fluid from leaking out of the hydraulic chamber  64  past the first and second pistons  61  and  62 . The first sealing member  81  is an O-ring having a rectangularly shaped cross-sectional profile with a cylindrical inner surface  81   a  contacting the first piston  61 . The second sealing member  82  is an O-ring having a rectangularly shaped cross-sectional profile with a cylindrical inner surface  82   a  contacting the second piston  62 . The phrase “cross-sectional profile” as used herein with respect to the first and second sealing members  81  and  82  refers to just a transverse cross section of a segment of the sealing members as shown in cross section in  FIGS. 12 to 14 . The phrase “cross-sectional profile” as used herein with respect to the first and second sealing members  81  and  82  does not refers a transverse cross section of the entire sealing member. The phrase “rectangularly shaped” as used herein with respect to the first and second sealing members  81  and  82  refers to an overall shape that is rectangular having four planar sides with opposite sides being parallel, and in which the corners can be rounded and/or cutoff at an angle. 
     Referring to  FIGS. 12 to 14 , the first and second sealing members  81  and  82  are configured to provide an automatic adjustment of the brake pad clearances between the bicycle rim R and the brake pads  26   b  and  28   b  after actuation of the bicycle rim brake  12 . In particular, after actuation when the brake lever returns to a rest position, the first and second sealing members  81  and  82  return the first and second pistons  61  and  62  back to their initial positions thereby providing a running clearance between the bicycle rim R and the brake pads  26   b  and  28   b . More specifically, when the first piston  61  is moved axially in the hydraulic chamber  64  along the actuation axis A 1  from a resting position ( FIG. 12 ) to an actuated position ( FIG. 13 ), the first sealing member  81  is deflected in the axial direction as seen in  FIG. 13 . In the actuated position of  FIG. 13 , the first sealing member  81  is temporarily deformed. The resulting deformation of the first sealing member  81  results in the first sealing member  81  applying a piston restoring force on the first piston  61 . Thus, once the hydraulic pressure is reduced in the hydraulic chamber  64 , the first sealing member  81  will act on the first piston  61  to return the first piston  61  to the resting position as seen in  FIG. 12 . 
     Before any wear occurs in the brake pads  26   b  and  28   b , movement of the first piston  61  causes the first sealing member  81  to deflect but the first piston  61  does not slide on the first sealing member  81 . Upon wear occurring in the brake pads  26   b  and  28   b , actuation of the first piston  61  will result in the first sealing member  81  to be first deflected and then the first piston  61  will slide on the first sealing member  81  to counteract the wear in the brake pads  26   b  and  28   b . Thus, a new resting position is established when the first sealing member  81  acts on the first piston  61  to return the first piston  61  to the resting position. The second sealing member  82  operates in the same way as the first sealing member  81 . 
     In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts unless otherwise stated. 
     As used herein, the following directional terms “frame facing side”, “non-frame facing side”, “forward”, “rearward”, “front”, “rear”, “up”, “down”, “above”, “below”, “upward”, “downward”, “top”, “bottom”, “side”, “vertical”, “horizontal”, “perpendicular” and “transverse” as well as any other similar directional terms refer to those directions of a bicycle in an upright, riding position and equipped with the bicycle rim brake. Accordingly, these directional terms, as utilized to describe the bicycle rim brake should be interpreted relative to a bicycle in an upright riding position on a horizontal surface and that is equipped with the bicycle rim brake. The terms “left” and “right” are used to indicate the “right” when referencing from the right side as viewed from the rear of the bicycle, and the “left” when referencing from the left side as viewed from the rear of the bicycle. 
     Also it will be understood that although the terms “first” and “second” may be used herein to describe various components these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, for example, a first component discussed above could be termed a second component and vice versa without departing from the teachings of the present invention. The term “attached” or “attaching”, as used herein, encompasses configurations in which an element is directly secured to another element by affixing the element directly to the other element; configurations in which the element is indirectly secured to the other element by affixing the element to the intermediate member(s) which in turn are affixed to the other element; and configurations in which one element is integral with another element, i.e. one element is essentially part of the other element. This definition also applies to words of similar meaning, for example, “joined”, “connected”, “coupled”, “mounted”, “bonded”, “fixed” and their derivatives. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean an amount of deviation of the modified term such that the end result is not significantly changed. 
     While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, unless specifically stated otherwise, the size, shape, location or orientation of the various components can be changed as needed and/or desired so long as the changes do not substantially affect their intended function. Unless specifically stated otherwise, components that are shown directly connected or contacting each other can have intermediate structures disposed between them so long as the changes do not substantially affect their intended function. The functions of one element can be performed by two, and vice versa unless specifically stated otherwise. The structures and functions of one embodiment can 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 which 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 foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.