Patent Publication Number: US-2003230160-A1

Title: Barend mounted twist shifter with integrated brake actuator for bicycle

Description:
PRIORITY CLAIM  
     [0001] The present US Application claims priority to the U.S. Provisional Application for a “Barend Mounted Twist Shifter with Integrated Brake Actuator for Bicycle”, Application No. 60/367,435, filed Mar. 20, 2002, which is hereby incorporated by reference. 
    
    
     
       FIELD OF INVENTION  
       [0002] The present invention relates to handlebar-mounted devices with integrated twist shifter and brake actuator.  
       BACKGROUND OF INVENTION  
       [0003] A bicycle may feature barends that are mounted at the peripheral ends of a handlebar. Such barends are commonly utilized to provide an ergonomic and comfortable position of the bike rider&#39;s hands. Barends conventionally are somewhat perpendicular orientated relative to a protrusion direction of the handlebar. The barends point with their outside diameter and their tips substantially in the steering direction. To the contrary, brake levers and shifters are still centrally placed at the laterally protruding portion of the handlebar close to the bicycle&#39;s steering column. Thus, even though barend extensions provide a comfortable grip contact with the handlebar, they have limited utility since hand positions have to be changed every time that braking or shifting is performed. Therefore, a need exists for a device that provides shifting and brake actuation at the barends.  
       [0004] Twist shifters provide a means for transforming a rotating hand motion around the handlebar into a derailleur actuation. Prior art shifting devices are actuated via a gripdrum that is mounted rotatable around the handlebar. A derailleur is commonly remotely actuated from the frontal portion of the bicycle via a pulling cable that is guided in a pulling force opposing fashion in a flexible tubular housing. A performance critical factor of the shifter-cable-derailleur assembly is the amount of cable pull initiated by actuating the gripdrum. In common prior art twist shifters, the gripdrum is rotationally rigidly combined with a spool at which the cable end is attached and around which the cable coils when the gripdrum is rotated.  
       [0005] A derailleur is commonly spring loaded, which is necessary to keep the cable under tension and to perform a downshifting when the shifter cable is released. During up shifting, when the cable is pulled, the spring load of the derailleur and friction in the mechanism needs to be overcome by the operating bike rider. Because of debris that usually accumulates in the joints and sliding parts of the shifter-cable-derailleur assembly, the required cable pull force may increase drastically. To keep the actuating torque at the gripdrum to a minimum, it is desirable to have the spool diameter as small as possible. A miniaturization of the spool diameter is limited by the handlebar&#39;s outside diameter, which in turn is defined by strength and stiffness requirements of the handlebar. Attempts have been made in the prior art to overcome this limitation by introducing additional transmission elements in the twist shifter. Unfortunately, additional transmission elements make the twist shifter heavier, less reliable and more costly to fabricate. Hence, there exists a need for a twist shifter that provides a direct cable pull via a spool rotatable connected to a gripdrum that rotates around a profile onto which a bike rider may hold on during bike riding. In addition, the desired minimal diameter of the twist shifter&#39;s spool should not be limited by that profile&#39;s outside diameter as is the case with prior art twist shifters. The present invention addresses this need.  
       [0006] Twist shifters have to provide a relatively large angular movement range of the gripdrum to accommodate for the ever-increasing number of required gear shifting positions. Unfortunately, a human&#39;s wrist has only a limited flexibility. A ratchet mechanism combined with the gripdrum may solve that problem. Unfortunately, in prior art twist shifters, the design space for such ratchet mechanism is significantly compromised by the handlebar around which the twist shifter is assembled. The available design space is further limited in handlebar direction by a common presence of a brake lever clamped onto the handlebar next to the twist shifter. Therefore, there exists a need for a twist shifter that may utilize a ratchet mechanism without limitations imposed by the handlebar and/or an adjacently clamped brake actuator. The present invention addresses this need.  
       SUMMARY OF INVENTION  
       [0007] A twist shifter is introduced that is configured for attaching and operating at a barend&#39;s tip. In that way, the bike rider may actuate a derailleur of the bicycle without taking his/her hands from the barends. The twist shifter may be combined with a brake actuator to provide brake actuation together with derailleur actuation in an ergonomic fashion.  
       [0008] The barend&#39;s tips are conventionally open ended and have to comply with relatively low strength and stiffness requirements. The twist shifter of the present invention takes advantage of this fact in various embodiments. In a preferred embodiment, the twist shifter is clamped on the inside of a hollow barend through the barend&#39;s open tip. The spool may thereby rotate around the internal clamping feature, thus making its minimum diameter highly independent from the barend&#39;s outside diameter.  
       [0009] In another embodiment, a ratchet mechanism is integrated in the twist shifter with a thumb perch actuated ratchet release. Since the twist shifter design is not hampered by the handlebar protruding all the way through the shifter, the ratchet mechanism may be freely designed adjacent the barend&#39;s tip and extending within the outside diameter of the barend.  
       [0010] The twist shifter may be configured to fit onto standardized barends. The twist shifter may be also configured in combination with a barend, which may be fabricated with specific features on its tips that may serve for attaching and/or as functional parts of the twist shifter. The barends themselves may be integral part of a handlebar or may be together with the inventive shifter be an independent unit readily attachable at the peripheral ends of the handlebar.  
       [0011] In accordance with the invention, a shifting device is provided. The shifting device comprises a housing configured for positioning at a tip of a profile and for attaching to said profile and a gripdrum rotatable combined with said housing for a rotatable access of said gripdrum around an outside diameter of said profile during said positioning of said housing, The device further comprises a spool in a functional connection with said gripdrum and rotatable embedded in said housing for pulling a derailleur actuating cable, said spool having a bushing diameter being smaller than said outside diameter.  
       [0012] In accordance with another aspect of the invention, a combined shifting and braking actuator is provided. The combined shifting and braking actuator comprises a shifting device and a brake actuator combined with a housing of the shifting device such that a brake lever is ergonomically accessed by a hand operating the grip drum of the shifting device. The shifting device further comprises a housing configured for positioning at a tip of a profile and for attaching to said profile, a gripdrum rotatable combined with said housing for a rotatable access of said gripdrum around an outside diameter of said profile during said positioning of said housing, and a spool in a functional connection with said gripdrum and rotatable embedded in said housing for pulling a derailleur actuating cable, said spool having a bushing diameter being smaller than said outside diameter.  
     
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
     [0013]FIG. 1 shows a shaded view of a bicycle&#39;s front portion including a handlebar with peripherally attached barend extensions wherein each barend has a barend mounted twist shifter and brake actuator in accordance with the invention.  
     [0014]FIG. 2 shows a perspective view of a first embodiment of a twist shifter with integrated brake actuator mounted on a tubular section representing a barend extension.  
     [0015]FIG. 3 shows more details of the first embodiment of the invention, without the gripdrum and the tubular section shown, wherein the device is configured for clamping to the inside of the barend extension.  
     [0016]FIG. 4 shows a second perspective view of the inventive device without the gripdrum and tubular section shown wherein an exemplary spool with an integrated spring is visible.  
     [0017]FIG. 5 illustrates a second embodiment of the twist shifter with an integrated brake actuator wherein the barend extension is an integral part of the inventive device.  
     [0018]FIG. 6 shows a further embodiment of the present invention, including a thumb perch that operates as a shifter release of a shifting ratchet.  
     [0019]FIG. 7 shows another embodiment of the twist shifter with integrated brake actuator with an inverted spool direction of the shifter cable.  
     [0020]FIG. 8 shows the second embodiment of the twist shifter with integrated brake actuator together with an inverted spool direction of the shifter cable.  
     [0021]FIG. 9 shows a schematic perspective view of a first exemplary internal shifting mechanism.  
     [0022]FIG. 10 shows a schematic perspective view of a second exemplary internal shifting mechanism. 
    
    
     DESCRIPTION OF THE INVENTION  
     [0023] As illustrated in FIG. 1, a bicycle  101  has a well-known handlebar  102  with barends  103  attached on to each end of the handlebar  102  as is well known. The barends  103  may also be an integral part of the handlebar  102 . The hands  104  of a person riding the bicycle  101  may rest on the barends  103  as exemplarily depicted in FIG. 1. A device  105 , which provide for a preferred combined shifting and brake actuating functions, is placed at each end of the barends  103 . Each device  105  may preferably include a rotating gripdrum  206  (see FIGS.  2 - 8 ) that provides the shifting function as described below and a brake lever  207  (see FIGS.  2 - 8 ) that provides the brake actuation function as described below. The gripdrum  206  and the brake lever  207  are configured and positioned for ergonomic and comfortable access and operation in a hand position as exemplarily depicted in FIG. 1 so that the rider may perform both the shifting operations and brake actuation operations while his/her hands remain on the barends. Cable housings  108 ,  109  protrude from each of the devices  105  and internally guide cables to a brake (not shown) and a derailleur (not shown) in a well-known fashion.  
     [0024] Now referring to FIG. 2, the main components of the device  105  are described. A housing structure  201  is shaped to hold a brake lever  207  that rotates about an axle  212 , encapsulate a well known shifting mechanism, retain the ends of the cable housings  108 ,  109 , and guide a shifter cable  404  (see FIGS. 4, 5) and a brake cable (not shown) in a well known fashion towards the cable housings  108 ,  109 . The housing structure  201  may optionally include adjustment screws  210 ,  211 , which are well known for adjusting brake and shifter motion.  
     [0025] The shifting operation is performed by rotating the gripdrum  206  around the barend  103 . For that purpose, the barend  103  has a straight cylindrical portion along the length of the gripdrum  206 . The cylindrical portion is mainly defined by its outside diameter. The gripdrum  206  is in a functional connection to a cable spool  401 ,  902 ,  1002  (see FIGS. 4, 5,  9 ,  10  below) of an internal shifting mechanism embedded inside the housing structure  201 , the inventive aspects of which are described in more detail with reference to FIGS. 4, 5. A functional connection may include a monolithic connection, a snap connection and or a ratchet mechanism as described in more detail below. The integration of the shifting mechanism and the brake actuator inside the housing structure  201  provides for a close positioning of the gripdrum  206  relative to the axle or pivot pin  212  around which the brake lever  207  pivots. As a result, the hands  104  of a rider may be placed close to the pivot pin  212  such that the brake lever  207  is comfortably accessed. The integrated shifter and brake actuator provides additionally for compact and lightweight design. The integrated shifter and brake actuator in accordance with the invention permits a bicycle rider to rest his hands  104  on the barends  103  and operate the bicycle&#39;s brakes and derailleur simultaneously.  
     [0026] The placement of the device  105  at the end of a barend  103  provides for particular design advantages unattainable with prior art shifting devices mounted at the well-known central portion of the handlebar  102 . Firstly, as shown in FIG. 3, the clamping of the device  105  may be accomplished inside of the barend  103 . In particular, the housing structure  201  may include an internal clamping mechanism  301  that, for example, transforms an axial force of a screw into a radial clamping force onto an inside diameter of a hollow barend  103  which may be carried out by any clamping mechanism including well known clamping mechanisms. For example, the clamping mechanism  301  may include a first portion  301   a  and a second portion  301   b  wherein the tightening of a screw (not shown) offsets the first portion from the second portion as shown which increases the effective diameter of the clamping mechanism. Thus, the device  105  with the internal clamping mechanism  301  is inserted into the barend and then the clamping mechanism  301  is tightened to secure the device  105  onto the barend. In the prior art, twist shifters are commonly clamped on the handlebar&#39;s circumference wherein a clamp embedded in the prior art shifter housing typically accomplishes this task. To the contrary, the present clamping mechanism  301  corresponds to the inside contour of the barend  103 . Since the clamping feature is put into the inside of the barend  103 , the housing structure  201  may be kept at a smaller width and/or scale than prior art shifter devices.  
     [0027] A second particular advantage of the present invention is that the shifting mechanism may be designed without dimensional constraints imposed by the outside diameter of the handle bar  102  and/or the barend  103 . These dimensional constraints, such as a particular diameter of the spool, are well-known in prior art twist shifters in which the shifting mechanism is designed to fit around the handlebar  102 . In particular, the rotation of the shifter is transmitted on the shifter cable via a well-known spool whereby the shifter cable is attached such that the cable wraps around the spool when the gripdrum is rotated. The diameter of the spool mainly influences the amount of torque that needs to be induced on the gripdrum for performing a shifting operation with a required cable pull force. Thus, a smaller spool diameter requires less torque to be induced on the gripdrum as may be well appreciated by anyone skilled in the art. In prior art cases, where the spool rotates around the handlebar, the diameter of the spool and hence the shifting torque reduction is limited by the handlebar&#39;s outside diameter. In the present invention, the device  105  is placed at the end of the barends  103  providing a bushing diameter of a spool  401 ,  902 ,  1002  (See FIGS. 4, 9 and  10 ) that may be smaller than the barend&#39;s  103  outside diameter. Preferably, the spool  401 ,  902 ,  1002  may rotate around a reduced diameter of the barend  103  or directly around the body of the clamping mechanism  301  as described below in more detail. The body of the clamping mechanism  301  may be accordingly configured with a continuously round shape and/or other well-known features and/or configurations for providing a well known bushing for the spool  401 ,  902 ,  1002 .  
     [0028]FIG. 4 illustrates a preferred embodiment in which the spool  401  rotates directly around the clamping mechanism  301 . In particular, the shifter cable  404  is held with its end and resting on the circumference of the spool  401 . When the spool  401  is rotated via the gripdrum  206  in a cable pull direction, the cable  404  wraps around the spool  401  and a pulling force is induced on the cable and transmitted onto a derailleur (not shown). When the spool  401  is rotated via the gripdrum  206  in a cable release direction, the cable  404  uncoils from the spool  401  and the tension of the cable is released and pulled back by the spring loaded derailleur, which then performs a shifting operation in a direction opposite to that during cable pulling. When the device  105  is inserted into a barend and secured into position, the end of the barend abuts the spool  401  so that the spool  401  is able to rotate.  
     [0029] The shifter cable  404  exits the enclosure of the housing structure  201  and is internally guided through the adjustment screw  211  into the cable housing  108  as is well-known for twist shifters. The spool  401  is rotating around the clamping mechanism, which is smaller than the outside diameter of the handlebar  102 . As a result, the required shifting torque is lower than in prior twist shifters having a spool rotating around the handlebar  102 . The clamping mechanism  301  may feature alignment shoulders (not shown) that position the device  105  on the barends  103  such that sufficient space remains for a free rotation of the spool  401 . Moreover, the spool  401  may have an open cross section allowing it to be enlarged in diameter during its assembly. Thus, the portion of the clamping mechanism  301  along which the spool  401  rotates may be further reduced in diameter.  
     [0030] The spool  401  may be fabricated from sheet metal such that a spring feature  402  may be provided together with the spool  401  as a single monolithic structure. The spring feature  402  snaps into a plurality of positioning grooves  403  located within the inner circumference of the housing structure  201 . The grooves  403  are positioned in correspondence with required cable pull distances for shifting to different particular gears as is well known and the outer diameter of the spool  401 . The spool  401  has a first shoulder  411 , which is actuated by a compressive force exerted by the rotated gripdrum  206 . The compressive force is exerted on the shoulder  411  during up shifting where the shifter cable is pulled. The spring  402  has a second shoulder  412 , which is pressed via a portion of the gripdrum  206  (not shown) during down shifting, during which the shifter cable is released. The second shoulder  412  is placed in a fashion such that the spring  402  is forced out of a groove  403  when the second shoulder  412  is pressed. As a result, the torque required for down shifting has to be merely at a level sufficient to lift the spring  402  out of its groove  403 . The spring  402  may be designed to provide a resistive torque against inadvertent down shifting while snapped in one of the grooves  403 .  
     [0031] As illustrated in FIG. 5, the scope of the present invention includes embodiments in which a modified barend  501  is specifically configured to operate with the device  105 . In particular, since the tip of the barends  103  need to provide relatively little strength and/or stiffness compared to the more central handlebar portions where conventional prior art twist shifters are commonly attached, the tip may be recessed in diameter and/or particularly shaped in a fashion diverging from the main tubular section shape. In that way, the barend tip have a slightly reduced diameter as shown and may fixedly hold the spool  401  and/or may provide a well-known interface for attaching the housing structure  201 . The modified barend  501  may be a separate part to be attached on the handlebar  102  or it may be integral part of a correspondingly shaped handlebar  102 . In the embodiments with the modified barend, no clamping mechanism  301  may be required.  
     [0032]FIG. 6 depicts a second embodiment of the present invention in which a well-known ratchet mechanism is provided. Such a well-known ratchet mechanism includes a first feature for transmitting a torque from a first lever on a modified spool while rotating in a first direction; a second feature for holding the modified spool in its rotational orientation against the cable force, while the first lever is released; and a third feature for releasing the spool in an angular amount that corresponds to a single shifting step of the attached derailleur. The third feature is commonly executed as a second lever. Conventional ratchet mechanisms have a main axis of revolution around which both first and second lever pivot.  
     [0033] In the second embodiment, the position of the device  605  at the tip of the barend  103  may be advantageously utilized for integrating a well-known ratchet mechanism adjacent to the tip of the barend  103 . The ratchet&#39;s main axis of revolution is thereby preferably brought into an orientation that is substantially concentric to a cylindrical tip of barend  103 . The first lever is replaced by the gripdrum  206  and the independently rotating thumb perch  601  replaces the second lever. The ratchet mechanism for converts a repeating back and forth rotation of the gripdrum  206  into a cable pulling rotation of the spool  401 ,  902 ,  1002 . A one-directional rotation blocking mechanism may block a free rotation of the spool  401 ,  902 ,  1002  in the cable releasing direction while allowing for a free rotation of the spool  401 ,  902 ,  1002  in the cable pulling direction. A release mechanism may release the blocking of the rotation blocker such that the spool  401 ,  902 ,  1002  may rotate into cable releasing direction while the release mechanism is actuated. The thumb perch  601  is part of the release mechanism for ergonomically actuating it by the thumb of the hand operating the shifter  605 . The ratchet mechanism may extending within the outside diameter of the barend  103  since it may be placed adjacent the tip of the barend  103 .  
     [0034] FIGS.  7 - 10  depict embodiments of the present invention, in which the pull direction of the spool  902 ,  1002  (see FIGS. 9, 10) is defined in a fashion such that a rotation in the direction of the index finger of a rider results in a pull on the shifter cable  404 . This has two advantages in combination with the barend position of the devices  705 ,  805 . First, a housing neck  702 ,  802  protrudes roughly tangentially and laterally from the upper portion of a cylindrical portion of the housing  701 ,  801 . The cylindrical portion is preferably concentric to the outside diameter of the barend  103 . The position of the neck  702 ,  802  corresponds ergonomically to a groove between the thumb and the index finger of the hands of a rider. As a result, a more reliable holding position on the barends  103  may be maintained, since the neck  702 ,  802  prevents the hands from accidentally slipping off the barends  103 .  
     [0035] A second advantage is established in combination with a third embodiment of the invention as depicted in FIG. 8. There, an actuator housing  806  is rigidly combined with the gripdrum  206 , such that the entire brake actuator, including an actuator housing  806  and a lever  207  rotate together with the gripdrum  206 . Thus, the torque necessary to initiate a gear shifting operation may be transmitted thereby from one of the hands onto the gripdrum  206  and/or the brake lever  207 . The shifting torque results in a force on the brake lever  207  that is along the pivot axis of the lever  207  defined by the axle  212  such that the brake lever  207  may not be unintentionally moved during shifting. Having an inverted cable pull direction provides for an independently initiated braking and shifting in a substantially unchanged holding position of the hand and fingers on the barend  103 .  
     [0036] In the third embodiment, a ratchet mechanism is utilized as described under FIG. 6, such that the brake actuator  207  is rotated only in a relatively small angular range compared to that of the first embodiment with a continuously rotating gripdrum  206 . The shifter housing  801  remains rigidly connected to the barend  103 . A thumb perch  803  may extend laterally from the shifter housing  801  in a region beneath the neck  802  where it can be pushed by the thumb in a fashion that corresponds to a natural holding position on the barend  103 . In order to decouple the rotational movement of the brake actuator  207  from the cable housing  805 , a rotating joint may be optionally included in the adjustment screw  804 .  
     [0037]FIGS. 9 and 10 schematically illustrate exemplary configurations of some internal shifter components as they may be utilized in the first embodiment of the invention. In FIG. 9, a spool structure  902  rotates around a central portion  906 , which may be part of the central fixture  301 , or a modified barend  501 , or the shifter housing  901 . The spool structure  902  has a spool groove  907  into which the shifter cable  404  is positioned while the spool structure  902  is rotated by pressing on the shoulder  911 . A substantially rigid pawl  905  hinges in the spool structure  902  and is pushed by an elastic member  904 , such as a spring, against the groove profile  903 . During up shifting, a pressure is exerted on a shoulder  911  high enough to overcome the preload of the shifter cable  404  and to force the pawl  905  against the elastic member  904  out of a snap position defined by one of the groove profile&#39;s  903  grooves. During down shifting, a pressure is exerted on a shoulder  912  of the pawl initiating a rotation of the pawl  905 . Once the pawl  905  is rotated out of it&#39;s snap position, the spool structure  902  is rotated by the remaining pressure on the shoulder  912  and/or the preload of the shifter cable  404  or is rotated by a dedicated down shifting spring member (not shown).  
     [0038] Since no clamping mechanism needs to be integrated inside the housing  901  and since the diameter of the central portion  906  may be kept relatively small compared to that of a conventional handlebar, all described functional shifter parts  902 ,  903 ,  904 ,  905 ,  906 ,  907 ,  911 ,  912  may be configured such that the shifter cable  404  is spooling within the height of the groove profile  903  rather than adjacent as commonly practiced in the prior art. The result is a highly compact shifting mechanism and a shifter housing  901  the cylindrical portion of which has an outer diameter of up too less than 40 mm.  
     [0039]FIG. 10 shows another embodiment in which a modified pawl  1005  is combined with a spool structure  1002  into a monolithic structure made from a material that is sufficiently stiff such that the pawl  1005  may operate with sufficient stiffness. The material is also sufficiently elastic such that it can deflect elastically in the interface between pawl  1005  and spool structure  1002  during rotation of the pawl  1005 . Such material may be for example a polyethylene. The shifter cable  404  is guided through the interface such that the enlarged cable end  405  holds itself on the opposing end and against the pulling force of the cable  404 . The spool structure  1002  has an arc like shape that provides for a simple assembly thereof. The spool structure  1002  wraps sufficiently around the central portion  1006  to snugly contact it in all shifting positions. A shoulder  1011  operates as described for shoulder  911  in FIG. 9. A shoulder  1012  operates as described for shoulder  912  in FIG. 9.  
     [0040] The highly compact design of the spool structure  1002  provides also for a cable spooling within the groove height as described under FIG. 9. In addition, the minimal space consumption of the spool structure  1002  provides sufficient space for other well-known elements of a shifting mechanism within the cylindrical portion of the shifter housing  1001 . Such additional elements may be part of a ratchet mechanism as described for the second and third embodiments. Also, a structural element  1007  may be integrated that bridges directly between the central portion  1006  and the housing  1001  of the brake actuator, which assists in optimizing the stiffness of the entire device  705 . Further more, the axle  212  may be brought within the outside contour of the barend  103  and into closest proximity to the central portion  1006 . This assists additionally in optimizing the geometric arrangement of the hand operated moving parts, such that shifting and braking may by performed in a comfortably and ergonomically optimized while holding on the barends  103 .  
     [0041] The scope of the invention includes embodiments, in which the devices  105 ,  605 ,  705  or  805  are provided without brake actuator. The scope of the invention includes embodiments, in which the devices  105 ,  605 ,  705  or  805  are integral part of a barend readily attachable to the peripheral ends of a handlebar  102 . The scope of the invention includes embodiments, in which the devices  105 ,  605 ,  705  or  805  are integral part of a modified handle bar having tips and outside diameter of an adjacent cylindrical section pointing substantially into steering direction when mounted on a bicycle  101 .  
     [0042] Accordingly, the scope of the invention described in the specification above is set forth by the following claims and their legal equivalent.