Method and apparatus for positioning a bicycle derailleur chain guide

Abstract: A bicycle derailleur of the type wherein a movable derailleur member (9) moves relative to another member (24, 26, 27) for positioning the chain guide (1) relative to a first sprocket and a second sprocket. An indicating member (37) is disposed on one of the movable derailleur member (9) or the other member, and an indicium (36, 38) is disposed on the other one of the movable member or the other member. A relative position between the indicating member (37) and the indicium (36, 38) indicates a position of the chain guide (1) relative to the first sprocket and the second sprocket. Thus, the derailleur may be adjusted to a desired position by moving the chain guide (1) so that the indicating member is set to a desired position relative to the indicium.

Description: BACKGROUND OF THE INVENTION The present invention relates to a chain guide positioning mechanism for a bicycle shifter. More specifically, it relates to a chain guide positioning mechanism for a derailleur that is used to change the engagement position of a chain that engages with a front or rear sprocket. A plurality of front chain wheels with different numbers of teeth are usually located at the front of a bicycle to allow a speed change. A chain is run from the front chain wheel to the rear sprocket consisting of a plurality of gears with different numbers of teeth, with a speed change being realized through the difference in engagement between the two. To change the engagement of the chain on the front chain wheel (for example) in order to make a speed change, the chain must be moved parallel and lined up with the position of the front chain wheel by a part called a front derailleur. If this parallel movement is not performed at the proper position, the engagement of the chain cannot be changed. The front derailleur is driven and positioned at the engagement change position according to the selected speed via a cable and by means of a shift lever mechanism attached to the handlebar. In the case of a three-gear front chain wheel, assembly and adjustment are performed in the following sequence. First, the front derailleur is fixed to the frame position, and a cable is run between the front derailleur and the shift lever mechanism located on the handlebar. Thereafter, the shift lever of the shift lever mechanism is moved to the low position, and the chain guide of the front derailleur is positioned at the location of the low gear of the front chain wheel. The position of the chain guide is adjusted by turning the low stopper bolt on the front derailleur so that the low gear position is attained, and the adjustment bolt of the cable adjustment unit of the shift lever mechanism is turned so that the tension of the inner cable is adjusted to its optimal setting. The shift lever of the shift lever mechanism is then moved to the top position, and the chain guide is also driven to the top gear. Thereafter, the top stopper bolt of the front derailleur is adjusted so that the position of this chain guide is optimized. Such derailleurs are designed so that the chain guide is supposed to be positioned at the location of the middle gear when the shift lever is moved to the middle position, but in actual practice the optimal position is not attained because of the relationship of the tension on the inner cable. Consequently, the adjuster of the cable adjustment unit must again be turned so that the chain guide will come to the location of the middle gear in order to adjust the tension on the inner cable. As a result, considerable time and skill is required for the assembly and adjusment of the chain guide positioning mechanism of a conventional bicycle derailleur. SUMMARY OF THE INVENTION The present invention is directed to a method and apparatus for positioning a bicycle derailleur chain guide which greatly simplifies assembly and adjustment of the derailleur mechanism. The specific position of the chain guide may be checked visually, and adjustment takes place in a manner which allows positioning of the chain guide to be performed quickly even by relatively unskilled workers. A first aspect of the invention comprises a chain guide positioning apparatus for a bicycle derailleur, the bicycle derailleur being adapted to be mounted on a bicycle frame which has a lower component extending horizontally substantially perpendicularly to the main axis of the bicycle, the bicycle derailleur being of the type wherein a movable derailleur member moves relative to another member for positioning a chain guide relative to a first sprocket and a second sprocket, comprises an indicating member disposed on one of the movable derailleur member or the other member; and an indicium disposed on the other one of the movable member or the other member; wherein a relative position between the indicating member and the indicium indicates a position of the chain guide relative to the first sprocket and the second sprocket; characterized in that: said other member is fixed to a mounting member, wherein the mounting member is adapted to mount the derailleur to said lower component of the bicycle frame. EP-A-067729 discloses a bicycle derailleur wherein a supporting member corresponding to said other member is mounted on a main tube of the bicycle member and wherein movement of the derailleur member relative to the supporting member is guided by a pin-and-slot arrangement. The position of the pin relative to the slot varies with the position of the chain guide relative to the sprockets. A second aspect of the invention comprises a method of positioning a chain guide for a bicycle derailleur, the bicycle derailleur being adapted to be mounted on a bicycle frame which has a lower component extending horizontally substantially perpendicularly to a main axis of the bicycle, the bicycle derailleur being of the type wherein a movable derailleur member moves relative to another member for positioning the chain guide relative to a first sprocket and a second sprocket, the derailleur having an indicating member disposed on one of the movable derailleur member or the other member and an indicium disposed on the other one of the movable member or the other member, the method comprising the steps of: indicating a position of the chain guide relative to the first sprocket and the second sprocket by the relative positions of the indicating member and the indicium; characterized in that the method further comprises the step of: fixing said other member to a mounting member, wherein the mounting member is adapted to mount the derailleur to said lower component of the bicycle frame. A third aspect of the invention comprises a method of adjusting a bicycle chain for a bicycle derailleur, the derailleur being of the type wherein a movable derailleur member moves relative to another member for positioning the chain guide relative to a first sprocket, a second sprocket and a third sprocket disposed between the first and second sprockets, the derailleur having an indicating member disposed on one of the movable derailleur member or the other member and an indicium disposed on the other one of the movable member or the other member, and wherein a shift lever is mounted on the bicycle, a cable is mounted between the shift lever and the derailleur for causing the chain guide to move in response to movement of the shift lever, and an adjusting mechanism is provided for adjusting the tension on the cable, characterized in that the method comprises the steps of: positioning the chain guide at a selected position relative to the third sprocket, the positioning step including adjusting the tension on the cable to cause the chain guide to move; and ceasing to adjust the tension on the cable when the indicating member aligns with the indicium. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a rear view of a particular embodiment of a front derailleur which incorporates a positioning apparatus according to the present invention; Figure 2 is a side view of the derailleur shown in Figure 1 showing a cable connection to a shift lever; Figure 3 is a top view of the derailleur shown in Figure 1; Figure 4 is a side view of the chain guide used with the derailleur shown in Figure 1; Figure 5 is a view of the derailleur taken along line V-V in Figure 3; and Figure 6 is a view taken along line VI-VI in Figure 2. DETAILED DESCRIPTION OF THE EMBODIMENTS As shown in the figures, a chain guide 1 has a groove with a U-shaped cross section, as shown in Figure 5, and is used to guide the chain by bringing it into contact with this groove surface during a shift. A lining 17 made of a synthetic resin with good lubricity is applied by a known method to the groove surface so that the chain will slide smoothly. The chain guide 1 chiefly comprises two guide plates 2 and 3. The upper portions of these guide plates 2 and 3 are integrally linked by an upper linking component 4 . This upper portion has an opening 5 formed in it. The chain (not shown) goes through this opening 5 , so that the chain is guided smoothly during a shift. At the lower end of the chain guide 1 , the guide plate 3 is bent into an L shape to form a lower linking component 6 . This end is fixed to the guide plate 2 by a screw 7 . The chain guide 1 is made of steel, the surface of which is plated with chrome so as to improve wear resistance. A movable link 9 and a link pin attachment component 10 are integrally arranged and fixed in parallel to the fore and aft positions of the chain guide 1 (see Figures 3 and 5). The movable link component 9 corresponds to the movable link that makes up part of the four-joint linking mechanism. The movable link 9 and the link pin attachment component 10 have three link pin support holes 12 made in them (see Figures 4 and 5), and are rotatably supported. Specifically, there are two holes in the movable link 9 and one in the link pin attachment component 10 . A movable link pin 13 is rotatably inserted into the link pin support hole 12 at one end of the movable link 9 . An L link 15 is further rotatably provided to the movable link 9 via a bushing 14 . The movable link 9 , the bushing 14 , and the L link 15 are rotatably linked and supported by the link pin 13 , and this linked and supported portion makes up one joint of the four-joint linking mechanism. A movable link pin 11 is inserted into the link pin support hole 12 and runs between the link pin attachment component 10 and the movable link 9 . The upper portion of a movable vertical link 16 is rotatably supported by this movable link pin 11 . A fixing flange 22 and a semicircular clamp ring 23 are fixed and supported by a horizontally arranged bottom bracket 20 that is part of the bicycle frame, and by a vertical frame that is integrally welded to this bottom bracket. The fixing flange 22 and the semicircular clamp ring 23 are used to fix a fixing link (member) 24 that is part of the four-joint linking mechanism to the bicycle frame. The semicircular clamp ring 23 is in contact with and encircles approximately one-half of the periphery of the vertical frame 21 , and is fixed to the fixing flange 22 . The fixing link 24 is fixed to the fixing flange 22 by a bolt 25 . The fixing flange 22 is fixed to the bottom bracket 20 by a nut, which means that the fixing link 24 is fixed to the fixing flange 22 . Parallel fixing flanges 26 are integrally formed at the upper portion of the fixing link 24 . A fixing link pin 27 runs between the fixing flanges 26 . The lower end of the movable vertical link 16 is rotatably supported by the fixing link pin 27 . Furthermore, one end of a fixing link 28 is fixed to one of the fixing flanges 26 . One end of the L link 15 is rotatably supported by the fixing link 28 . The other end of the L link 15 is rotatably supported by the movable link pin 13 . A coil spring 29 is arranged around the outside of the fixing link 28 , and the coil spring 29 constantly energizes the L link 15 in one direction, i.e., it energizes the chain guide 1 to the low side. As a result, the movable link pin 13 , the L link 15 , the movable link 9 , the movable link pin 11 , the movable vertical link 16 , the fixing flanges 26 , the fixing link pin 27 , the fixing link 24 , and the fixing link 28 make up a parallel four-joint linking mechanism. The L link 15 drives the parallel four-joint linking mechanism, moves the chain guide 1 parallel during a shift, and drives the chain. A cable fixing bolt unit 8 is arranged at one end of the L link 15 . The cable fixing bolt unit 8 is used to fix one end of a cable 43 that is operated by the shift lever 41 in order to make a shift with the shift lever 41 of the shift lever mechanism 40 fixed to the handlebar. The tension on the cable 43 is adjusted by an adjustment bolt 42 . The chain guide 1 is energized to the fixing link 24 side by the coil spring 29 of the fixing link 28 . This position is the position at which the cable 43 is not pulled by the shift lever 41 , and is the position at which the chain is guided by the chain guide to the position of the smallest diameter of the triple front chain wheel (not shown). This position is the low position in a shift operation, and this low position is determined when the side face of the guide plate 2 of the chain guide 1 hits the low stopper 30 provided to the side end of the fixing flanges 26 . The top position of the chain guide 1 is defined by the top stopper 31 that integrally extends to the fixing link 24 . The top stopper 31 hits the outer side face of the guide plate 3 of the chain guide 1 with its stopper surface 32 , and guides and restricts the chain to the position of the largest diameter of the triple front chain wheel. A graduated display 36 is scribed into the movable link 9 . The graduated display 36 is used when the chain is guided by the chain guide 1 to the middle position, ie., to the position of the middle diameter of the triple front chain wheel. Meanwhile, the lower end of the indicator needle 37 (made from a sheeting material) is fixed to the fixing link pin 27 , so the indicator needle 37 does not move. The locus display 38 made fore and aft of the graduated display 36 indicates the locus of the tip of the indicator needle 37 . The system is designed such that the chain guide 1 will be in the middle position when the indicator needle 37 and the graduated display 36 line up. The method for adjusting the above-mentioned chain guide positioning mechanism will now be described. First, the shift lever mechanism 40 , the chain guide positioning mechanism, the cable 43 , and various other parts are attached to the handlebar and the frame by specified methods. The procedure for these attachments is the same as in the past The following adjustment procedure is then undertaken. (1) The shift lever 41 on the handlebar is moved to the middle position. (2) The adjustment bolt 42 of the cable adjustment unit of the shift lever 41 is turned to adjust the cable 43 to the proper tension and line up the indicator needle 37 with the graduated display 36 . (3) The shift lever 41 is moved to the top position and the low position, the operation is checked, and the adjustment is complete. Once the middle position has been adjusted properly, since the middle position is located halfway between the top and low positions, the top and low positions are determined by design. Also, since the low and top positions of the chain guide 1 are defined by the low stopper 30 and the top stopper 31 , the chain guide 1 is positioned properly. 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 above practical example dealt with a three-speed type of front chain wheel, but the present invention may also be applied to a two-gear type with only top and low gears. Also, the above practical example involved a top stopper 31 in the form of an arm that extended in an L shape, but the stroke may also be adjusted by arranging the adjustment bolt over the movable link 9 as in the past. A low stopper 30 was described but the portion where the fixing link 24 hits the side face of the guide plate 2 , which is mechanically determined even without the provision of the low stopper 30 , may instead serve as the low stopper. Of course, the teachings of the present invention also could be applied to a rear derailleur. Thus, the scope of the invention should not be limited by the specific structures disclosed. Instead, the true scope of the invention should be determined by the following claims. Furthermore, although labelling symbols are used in the claims in order to facilitate reference to the figures, the present invention is not intended to be limited to the constructions in the appended figures by such labelling.

Claims: A chain guide positioning apparatus for a bicycle derailleur, the bicycle derailleur being adapted to be mounted on a bicycle frame (21) which has a lower component (20) extending horizontally substantially perpendicularly to a main axis of the bicycle, the bicycle derailleur being of the type wherein a movable derailleur member (9) moves relative to another member (24, 26, 27) for positioning a chain guide (1) relative to a first sprocket and a second sprocket, and comprising: an indicating member (37) disposed on one of the movable derailleur member (9) or the other member (24, 26, 27); and an indicium (36, 38) disposed on the other one of the movable member (9) or the other member (24, 26, 27); wherein a relative position between the indicating member (37) and the indicium (36, 38) indicates a position of the chain guide (1) relative to the first sprocket and the second sprocket; characterised in that : said another member (24, 26, 27) is fixed to a mounting member (22), wherein the mounting member (22) is adapted to mount the derailleur to said lower component (20) of the bicycle frame. An apparatus as claimed in Claim 1, wherein the bicycle derailleur is of the type wherein the movable derailleur member (9) moves relative to the other member (24, 26, 27) for positioning the chain guide (1) relative to a third sprocket, the third sprocket being disposed between the first sprocket and the second sprocket, and wherein the relative position between the indicating member (37) and the indicium (36, 38) indicates a position of the chain guide (1) relative to the third sprocket. An apparatus as claimed in either preceding Claim, wherein the other member (24, 26, 27) comprises a non-moving fixed member. An apparatus as claimed in any preceding Claim wherein the means for mounting the derailleur relative to the frame (21) of the bicycle further includes additional locating means (23) adapted to engage said frame (21) at a point above said lower component (20). An apparatus as claimed in either of Claims 3 or 4, wherein the indicating member (37) comprises a projecting member coupled to the fixed member, and wherein the indicium (36, 38) comprises a marking disposed on the movable derailleur member (9). An apparatus as claimed in any preceding Claim wherein the derailleur comprises: a first link (15) pivotally coupled to the mounting member (22); a second link (9) coupled to the first link (15) and to the chain guide (1) for moving the chain guide (1) in response to pivoting of the first link (15). An apparatus as claimed in Claim 6 wherein the indicium (36, 38) is disposed on the second link (9). An apparatus as claimed in either of Claims 6 or 7, wherein the indicating member (37) comprises an indicating projection coupled to the fixed member, and wherein the indicium (36, 38) comprises a marking disposed on the second link (9). An apparatus as claimed in any one of Claims 6 to 8, wherein the second link (9) moves the chain guide (1) laterally relative to the bicycle frame (21), and wherein the derailleur further includes : a first positioning member (30) for positioning the chain guide (1) at the first sprocket; and a second positioning member (31) for positioning the chain guide at the second sprocket. An apparatus as claimed in Claim 9, wherein the chain guide (1) comprises: an inner guide plate (2) coupled to the second link (9); an outer guide plate (3) coupled to the inner guide plate (2) for defining an opening (5) through which a drive chain may pass; wherein the first positioning member (30) is coupled to the mounting member (22) for limiting inward lateral movement of the chain guide (1); and wherein the second positioning member (31) is coupled to the mounting member (22) for limiting outward lateral movement of the chain guide (1). An apparatus as claimed in Claim 10, wherein the first positioning member (30) is disposed for abutting against the chain guide (1) when the chain guide (1) is positioned at the first sprocket, and wherein the second positioning member (31) is disposed for abutting against the chain guide (1) when the chain guide (1) is positioned at the second sprocket. An apparatus as claimed in either one of Claims 10 or 11, wherein the first positioning member (30) is disposed for abutting against a laterally inner side surface of the inner guide plate (2) when the chain guide (1) is positioned at the first sprocket, and wherein the second positioning member (31) is disposed for abutting against a laterally outer side surface of the outer guide plate (3) when the chain guide (1) is positioned at the second sprocket. An apparatus as claimed in any one of Claims 4 to 12, further comprising: a shift lever (41) for mounting to the bicycle; a cable (43) connected between the shift lever (41) and the first link (15); and a cable adjustment unit (42) used to adjust the tension on the cable (43). A method of positioning a chain guide (1) for a bicycle derailleur, the bicycle derailleur being adapted to be mounted on a bicycle frame (21) which has a lower component (20) extending horizontally substantially perpendicularly to a main axis of the bicycle, the bicycle derailleur being of the type wherein a movable derailleur member (9) moves relative to another member (24, 26, 27) for positioning the chain guide (1) relative to a first sprocket and a second sprocket, the derailleur having an indicating member (37) disposed on one of the movable derailleur member (9) or the other member (24, 26, 27) and an indicium (26, 38) disposed on the other one of the movable member (9) or the other member (24, 26, 27), the method comprising the step of: indicating a position of the chain guide (1) relative to the first sprocket and the second sprocket by the relative positions of the indicating member (37) and the indicium (36, 38); characterised in that the method further comprises the step of : fixing said another member (24, 26, 27) to a mounting member (22), wherein the mounting member (22) is adapted to mount the derailleur to said lower component (20) of the bicycle frame. A method as claimed in Claim 14, wherein the bicycle derailleur is of the type wherein the movable derailleur member (9) moves relative to the other member (24, 26, 27) for positioning the chain guide (1) relative to a third sprocket, the third sprocket being disposed between the first sprocket and the second sprocket, and wherein the indicating step further comprises the step of: indicating a position of the chain guide (1) relative to the third sprocket by the relative positions of the indicating member (37) and the indicium (36, 38). A method as claimed in either one of Claims 14 or 15, wherein a shift lever (41) is mounted on the bicycle, a cable (43) is mounted between the shift lever (41) and the derailleur for causing the chain guide (1) to move in response to movement of the shift lever (41), and an adjustment mechanism (42) is provided for adjusting the tension on the cable (43), and wherein the method further comprises the step of: adjusting the tension on the cable (43) to cause the chain guide (1) to move; and ceasing to adjust the tension on the cable (43) when the indicating member (37) and the indicium (36, 38) are at a predetermined relative position. A method as claimed in Claim 15, wherein a shift lever (41) is mounted on the bicycle, a cable (43) is mounted between the shift lever (41) and the derailleur for causing the chain guide (1) to move in response to movement of the shift lever (41), and an adjustment mechanism (42) is provided for adjusting the tension on the cable (43), and wherein the method further comprises the step of: positioning the chain guide (1) at a selected position relative to the third sprocket, the positioning step including: adjusting the tension on the cable (43) to cause the chain guide (1) to move; and ceasing to adjust the tension on the cable (43) when the indicating member (37) and the indicium (36, 38) are at a predetermined relative position. A method of adjusting a chain guide (1) for a bicycle derailleur, the derailleur being of the type wherein a movable derailleur member (9) moves relative to another member (24, 26, 27) for positioning the chain guide (1) relative to a first sprocket, a second sprocket and a third sprocket disposed between the first sprocket and the second sprocket, the derailleur having an indicating member (37) disposed on one of the movable derailleur member (9) or the other member (24, 26, 27) and an indicium (36, 38) disposed on the other one of the movable member (9) or the other member (24, 26, 27), and wherein a shift lever (41) is mounted on the bicycle, a cable (43) is mounted between the shift lever (41) and the derailleur for causing the chain guide (1) to move in response to movement of the shift lever (41), and an adjustment mechanism (42) is provided for adjusting the tension on the cable (43), characterized in that the method comprises the steps of: positioning the chain guide (1) at a selected position relative to the third sprocket, the positioning step including: adjusting the tension on the cable (43) to cause the chain guide (1) to move; and ceasing to adjust the tension on the cable (43) when the indicating member (37) aligns with the indicium (36, 38). A method as claimed in either of Claims 17 or 18, wherein the shift lever (41) is capable of movement between a first position and a second position, and wherein the method further comprises the step of: moving the shift lever (41) to a position intermediate the first position and the second position before adjusting the tension on the cable (43).

Inventors: MIZUNO TOSHIO, TERADA MASAO, MIZUNO, TOSHIO, TERADA, MASAO, Mizuno, Toshio, c/o Shimano Inc., Terada, Masao, c/o Shimano Inc.
Applicants: SHIMANO KK, SHIMANO INC.
Application year: 1995
Main classification: B62M9
IPC codes: B62M25, B62M9