GB2169065A - Indexing mechanisms and controls embodying the same - Google Patents

Abstract

An indexing mechanism for use in a trigger control for a bicycle or like change speed hub wherein an indexing member (19) Fig. 2, is selectively engageable with the periphery of the indexing wheel (11) to effect angular adjustment thereof, the indexing member (19) being pivotally mounted on a control plate (18) arranged coaxially with the indexing wheel (11) so as to extend radially therefrom and being capable of limited angular motion relative to the control plate (18) before engagement of a nose (23) of the indexing member with the indexing wheel (11). A stepwise release means Fig. 4; controlling incremental motion of the trigger control has two parallel arrays of detents on either side of the indexing member 19, with detent of one array laterally offset in relation to the alter array. Spaced lugs 37 and 38 on the release mechanism selectively cooperate with respective arrays of detents. <IMAGE>

Description

SPECIFICATION Index mechanisms and controls embodying the same The invention concerns indexing mechanisms, and has particular, though not exclusive, reference to such mechanisms, for use in gear selection means for bicycle and like change speed hubs.

The object of the invention is to provide an indexing mechanism of application to the context of a gear selection means for controlling the setting of a bicycle or like multi-speed hub.

According to the present invention there is proposed, in or for a trigger control for a bicycle and like change speed gear, an indexing mechanism comprising an indexing wheel, a carrier plate mounted coaxially with the said indexing wheel for angular motion relative thereto, an indexing member carried by the control plate and movably mounted thereon for adjustment angularly thereof, and selectively cooperable drive formations on the indexing wheel and indexing member, respectively, the drive formations being mutually engageable on adjustment of the indexing member from a datum position relative to the control plate in an appropriate sense and being adapted, upon continued movement in the same sense to transmit a drive motion to the indexing wheel, the mechanism further comprising return means biasing the indexing member to the said datum position relative to the control plate when displaced therefrom.

According to a preferred feature of the invention the indexing lever is pivotally secured to the control plate as a generally radial extension thereto, being pivotable about an axis parallel to the rotational axis of the control plate, and the selectively cooperable drive formations comprise a formation on the indexing member for selective engagement with one of a plurality of cooperable formations on the indexing wheel.

According to a further preferred feature the indexing lever is operable to adjust the angular disposition of the indexing wheel in either direction of movement thereof.

According to the present invention there is also proposed a stepwise release means for the indexing mechanism of a bicycle or like change speed gear trigger control, which indexing mechanism includes an indexing body adjustable in increments in a first direction against resilient restraint means, the release means comprising plural arrays of detent formations arranged in adjacent parallel disposition on the indexing body, at least one of the individual detents of one array being in laterally offset disposition in relation to the corresponding detent of another array, a release member, spaced lugs on the release member, each for selective cooperation with a respective one of the said arrays, a restraint means resiliently resisting motion of the release member.

The invention will now be described further, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a plan view of a first form of trigger control for a bicycle or like multi-speed hub embodying the invention; Fig. 2 is an underaside plan view of the arrangement shown in Fig. 1, parts having been removed in the interests of clarity; Fig. 3 is a scrap view, drawn to a larger scale, of a part of the structure shown in Fig.

2; Figs. 4 and 4a are diagrammatic perspective view and corresponding scrap view of the return mechanism of the arrangement shown in Figs. 1 and 2; Fig. 5 is a plan view of a single lever control for a bicycle or like five-speed hub embodying the invention; Fig. 6 is a plan view, partly in section, and drawn to a different scale, of a part of the structure shown in Fig. 5; Fig. 7 is a side elevation of the arrangement shown in Fig. 5; Fig. 8 is an underneath plan view of the control shown in Figs. 5 and 7; Fig. 9 is a view corresponding to Fig. 8, with parts omitted in the interests of ciarity; and Fig. 10 is a section on line X-X of Fig. 9.

Referring now to the drawings, and in particular to Figs. 1 to 4 thereof, a trigger mechanism for the linear adjustment of the control cable of a bicycle or like three-speed hub comprises an indexing wheel 11 rotatably mounted in a generally rectangular casing 12 and having an aperture 13 and slot 14 therein to receive the nipple 15 and the end region 16, respectively, of the control cable 17. An elongate carrier plate 18 is mounted coaxially with the wheel for angular adjustment relative thereto, the plate extending beyond the periphery of the wheel and pivotally supporting an indexing member 19 at its remote end and as an extension thereto.Drive formations 21, 22 are provided on the periphery of the indexing wheel 11 for selective engagement by a cooperable drive formation 23 on indexing member 19, for use in effecting angular displacement of the indexing wheel against the restraint of a return spring 24 connected between such wheel and the casing 12, all in a manner hereafter to be disclosed.

The mechanism further includes a second return spring 25 between the carrier plate 18 and the casing, the spring 25 resisting motion of the carrier plate 18 in an adjustment direction of the mechanism.

Drive formations 21, 22 comprise contact surfaces arranged in angularly spaced radial disposition at the periphery of the indexing wheel 11, whilst cooperable drive formation 23 comprises a nose extending from the indexing member 19 in the peripheral direction of the indexing wheel 11 and in closely spaced opposed relationship thereto. A fixed abutment member 26 is provided at one end of a slot 27 in the side wall of the casing 30 through which the indexing member extends, the slot extending through approximately 110" of arc. Member 26 is positioned adjacent the periphery of the indexing wheel 11 and at that side of the indexing member 19 remote from drive formation 23, member 26 being at the same or a similar radial distance from the axis of the carrier plate 18 as is a pivot pin 28 which secures the indexing member 19 to the indexing wheel 11.Return spring 25 operates to return the carrier plate 18 to a datum position defined by abutment member 26 after displacement from such position.

The operation of the mechanism thus far described is such that on movement of indexing member 19 in the direction of arrow A in Fig. 2, such member pivots in clockwise direction about pin 28 and thus moves the nose which defines drive formation 23 towards to the periphery of the indexing wheel.

Continued such pivotal motion of the indexing member 19 will bring drive formation 23 into contact with the periphery of indexing wheel 11, thus preventing further relative pivotal motion between indexing member 19 and carrier plate 18. Continued movement of the indexing member 19 will cause the carrier plate 18 and indexing member 19 to move in unison about the centre of the indexing wheel and against the restraint of return spring 25 to bring drive formation 23 into full depth engagement with the contact surface which constitutes drive formation 22. Still further angular movement of indexing member 19 in an appropriate amount will move the indexing wheel 11 against the restraint of spring 24 and will thus shift the control cable 17 longitudinally to effect the necessary gear adjustment.

The indexing wheel will be automatically retained in its adjusted position by suitable means hereafter to be described, and the indexing member 19 and carrier plate 18 will be returned to an initial position in contact with abutment 26 by return spring 25.

The relative disposition of parts shown in Fig. 2 is consistent with the selection of the intermediate gear of the three-speed hub to which cable 17 is connected, adjustment to such position from low gear having previously been effected by engagement of drive formation 23 with drive formation 21 and rotational adjustment of the indexing wheel 11 by movement of indexing member 19 in like manner to that previously described.

It will be apparent from the drawing that initial pivotal motion of the indexing member about pin 28 will initiate movement of the carrier plate 18 by reaction between abutment 26 and that part of the indexing member adjacent thereto, but the primary movement at this stage is the relative pivotal movement between the carrier plate and indexing member such as brings drive formation 23 into position for engagement with drive formation 21 or 22.

The geometry of the structure is such that a lost motion exists as between movement of the nose, or drive formation, 23 of the indexing member and its engagement with the cooperating drive formations 21, 22.

Retention of the indexing wheel in an adjusted position and its selective release from such position is effected by a stepwise release means 32.

Referring now to Figs. 4 and 4a, the stepwise release means 32 comprises upper and lower arrays 33, 34 of detent formations at an edge 35 of the indexing wheel 11 and a spring-loaded release member 36 bridging said edge and having opposed, inwardly facing ratchets 37, 38 each for selective engagement with a respective one of the said arrays.

The upper array 33 of detent formations comprises a cut-away 39 in the peripheral region of the indexing wheel 11 and a radial ratchet tooth 41 intermediate the angular extent of such region, the ratchet tooth 41 having an upright front operating face 42 and an inclined rear or camming face 43. A further operating face 44 is provided in the cut-away region 39 at that side of the ratchet tooth 41 remote from the upright operating face 42 thereof.

The lower array 34 comprises a further cutaway 45 in the periphery of the indexing wheel 11, such further cut-away being of similar, though slightly greater, arcuate extent to region 39 and in angular alignment therewith.

Two ratchet teeth 46, 47 are provided in cutaway 45, such teeth having respective upright radial operating faces 48, 49 and respective rear camming faces 51, 52. A further upright radial operating face 53 is provided at that end of cut-away 45 remote from operating face 48, face 53 being in angularly offset disposition relative to operating face 44 of array 33.

Operating face 42 of ratchet tooth 41 lies intermediate faces 48, 49 of teeth 46, 47 in the peripheral direction of the indexing wheel, whilst the ends of the cut-aways 39, 45 remote from operating faces 44, 53 respectively are in axial alignment.

Release member 36 consists of a generally rectangular body 54 having a quadrant shaped cut-out 50 in the wall thereof of a radius corresponding to that of the indexing wheel 11, the vertical extent of the cut out being such as freely to receive the periphery of the wheel 11 into engagement therewith. The underside of the body 54 is formed with a step 55 at that corner thereof diagonally opposite cut out 50 to provide a seating for a return spring 56, the top of the body being stepped to define a peripheral shoulder 57 to engage the underside of the top 58 of the casing 30 within which the mechanism is housed, there being an aperture 59 in such casing through which the reduced dimension part 61 of the top of the body extends.

Ratchets 37, 38 extend inwardly of the body from the upper and lower surfaces of the cut-out 50 therein, said ratchets being in alignment and being directed radially of such cut out. The adjacent parallel edges 62, 63 of ratchets 37, 38 sre separated by a distance in excess of the thickness of the indexing wheel in the region of aligned cut aways 39, 45 but less than such thickness plus the height of the ratchet teeth 41, 46, 47.

In the assembled condition of the trigger mechanism body 54 is engaged with the periphery of the indexing wheel 11 with ratchets 37, 38 in position for engagement with the upper and lower arrays 33, 34 respectively.

In use, and with release member 36 loaded outwardly of the casing 30 by return spring 56, ratchet 38 is engaged with the lower array of detent formations at an angular position therein appropriate to the gear selection as determined by the last operation of indexing member 19, being held in surface contact with the relevant radial operating face 48, 49, 53 by return spring 24 acting on the indexing wheel. It is to be observed that, in the use condition of the mechanism, cable tension serves also to urge ratchet 38 into surface contact with the relevant operating face, and the primary purpose of return spring 24 is to position indexing wheel 11 prior to cable fitment.

Assuming the ratchet 38 to be engaged with radial operating face 48, movement of the release member 36 against the restraint of return spring 56 will move the ratchet 38 across face 48 and out of engagement therewith, the indexing wheel thus being free to rotate under the effect of return spring 24 or the tension in cable 17 when fitted. However, as ratchet 38 moves out of engagement with the lower array 34, the opposing ratchet 37 moves into the path of movement of radial operating face 42 of the upper array 33, thus limiting the range of angular movement of the indexing wheel. On release of member 36, such member moves upwardly under the effect of return spring 56, ratchet 37 disengaging from operating face but ratchet 38 moving into the path of movement of operating face 49 to prevent further angular movement of the indexing wheel.

On a subsequent actuation of the release member 36, ratchet 38 is brought into engagement with radial face 53 in anaiogous manner.

Thus it will be seen that gear adjustment in either sense can be effected, adjustment in one direction being controlled by operation of indexing member 19 and in the other direction by operation of release member 36, the adjustment in each case being an increment appropriate to the extent of longitudinal displacement of the control cable necessary to shift the moving parts of the change speed gear hub a relevant amount.

A second embodiment of the invention is illustrated in Figs. 5 to 10, the arrangement shown therein being intended for the control of a 5-speed bicycle or like hub through a single lever, notwithstanding that two control cables are utilised in effecting adjustment of the hub.

Thus referring now to Figs. 5 to 10 of the drawings, a single lever trigger control for a 5-speed hub comprises an indexing wheel arrangement 66 angularly adjustable in increments about the rotational axis therof, springloaded location means 67 operable on the periphery thereof and adapted to hold the same in adjusted position, an edge cam 68 arranged coaxially with the indexing wheel arrangement 66 and rotatable therewith under the control thereof, superimposed cable levers 69, 71 positioned in alignment with the cam 68 and having respective cam followers 72, 73 thereon for co-operative engagement with the cam surfaces 74, 75 of the edge cam 68, a trigger mechanism 76 cooperable with the indexing wheel arrangement 66 and adapted, upon actuation, to effect incremental angular adjustment of said arrangement 66 and of the edge cam 68 rotatable therewith, and a housing 77 within which the aforesaid structure is mounted.

The indexing wheel arrangement 66 comprises spaced toothed wheels 78, 79 mounted on a square shaft, the outer face of wheel 78 being stepped, as at 81, for engagement with an aperture 82 in the top of the housing 77 for rotatably mounting wheel 78 therein. The inner face of wheel 78 has a central blind bore 83 of square cross-section to receive an indexing shaft 84 of like crosssection into engagement therewith. A collar 85 is provided about the blind bore, the outer periphery of the collar being of cylindrical form. Wheel 79 has a central aperture 86 of square section for engagement with the indexing shaft and that face of the wheel adjacent wheel 78 is of planar form and seats on the top of collar 85. The opposite face of wheel 79 likewise has a collar 87 about the through hole 86 therein, such collar also having a cylindrical outer periphery.

The respective peripheries of toothed wheel 78, 79 are of like form, save in that the teeth on wheel 78 do not extend to the outer face thereof.

Edge cam 68, which cam will be described in greater detail hereafter, is of generally circular form, and has an axial through hole 88 of square cross-section, again for engagement with the indexing shaft 84. Cam 68 seats against collar 87 when engaged with indexing shaft 84.

At its upper end indexing member 84 includes a cylindrical extension 89 for rotatable engagement with a seating in the removable base 91 of the housing 77. Indexing shaft 84 further includes a rib 92 extending longitudinally of one side face thereof, there being complementary grooves in blind bore 83 in toothed wheel 78, aperture 86 in toothed wheel 79 and through hole 88 in edge cam 68 to ensure appropriate relative angular dispositions of the wheels and cam on assembly of the trigger control.

Location means 67 comprises a detent member 92 movable longitudinally of a correspondingly shaped recess 93 formed in the housing 77, the nose 94 of the detent member being of semi-circular form and being dimensioned for complementary engagement with the toothed peripheries of the superimposed indexing wheels 78, 79 under the influence of a compression spring 95 interposed between the detent member 92 and the inside surface 96 of the wall of the housing.

Housing 77 is of generally rectangular, moulded form, and comprises a top 97 and a side wall structure 98 integral therewith, the housing further including the removable base 91 aforesaid.

Top 97 includes aperture 82 in which the stepped outer face of toothed wheel 78 is seated and is itself of stepped form at one side thereof, there being a slot 99 in the side wall between the stepped levels of top 97 for a purpose hereafter to be made apparent.

The toothed wheels 78, 79 lie in lateral register with slot 99, whilst cable levers 69, 71 are accommodated in the space at the underside of the downwardly stepped portion of the housing top, being pivotally mounted therein on a common pin 101 engaged in seating (not shown) in the housing top 97 and a seating 103 in the removable base 91.

Trigger mechanism 76, which mechanism is best shown in Fig. 6, comprises a trigger member 104 of elongate, generally isosceles triangular form pivotally connected with a trigger plate 105 pivotally connected in alignment therewith, there being resilient means 106 intermediate member 104 and plate 105 resisting angular movement therebetween. Trigger member 104 is symmetrical about a line passing through the apex thereof, and that end face thereof which receives the trigger plate 105 into pivotal connection therewith is of profiled form to provide forwardly facing spaced detents 107, 108 arranged one at each side of the said centre line.As is shown in Fig. 6, the trigger member is of hollow form to receive the resilient means 106 aforesaid, said resilient means comprising an elongate body of a resilient plastics material of which one end seats in the apex of the trian gular cavity in the trigger member and of which the other end terminates in a bifurcated connection 109 to receive the end of the trigger plate 105, the contacting parts of the resilient means 106 and the trigger plate 105 being so formed as to provide a positive and non-pivotal connection thereat.

Trigger plate 105 has a washer-like central section 111 for engagement between the toothed wheels 78, 79 and location by collar 85 on wheel 78 and a radial extension 112 of which the extremity engages the bifurcated connection 109 provided on resilient means 106. At a position angularly spaced from ex terision 112 the trigger plate includes a lug 113 to receive the ends of a torsion spring 114 in the manner shown in Fig. 9, such lug, in the assembled condition of the control and in the rest condition of the structure (as is shown in fig. 9) overlying a lug formed integrally with the housing and in the angle between the top of such housing and the wall thereof.

As is apparent from a consideration of Fig.

9, trigger mechanism 76 is positioned in the housing and relative to the toothed wheels 78, 79 with the detents 107, 108 thereof in adjacent spaced relationship with respect to the teeth of such wheels the mechanism being pivotal about the axis of such wheels and, on such pivotal motion of the mechanism the detents will move in the peripheral direction of the toothed wheels.

If the trigger member 104 is pivoted relative to the trigger plate the appropriate detent 107, 108 according to the direction of pivotal motion will move towards the teeth on the toothed wheels and into engagement therewith.

Thus, by effecting pivotal motion of the trigger member 104 about the trigger plate 105 in an appropriate sense, thus to bring the relevant detent into engagement with the periphery of the wheels, before rotation of the trigger mechanism 76 about the axis of the toothed wheels 77, 78, a subsequent rotational motion of the trigger mechanism will cause the wheels to be indexed by an amount determined by the extent of the further movement of the trigger member, detent member 92 being displaced against the restraint of the related compression spring 95. On release of the trigger member 104 such member will return to a position of alignment with the trigger plate 105 under the influence of resilient means 106, whilst trigger mechanism 76 will return to its datum position due to torsion spring 114.

As is apparent, trigger mechanism 104 is operable in either direction, and thus the toothed wheels can likewise be indexed in either direction.

in order to provide a limit to the extent of angular movement of the toothed wheels 78, 79, two of the teeth on the toothed wheels are backed-off, as at 115, 116 such that detents 107, 108 are not drivingly engageable therewith thus providing a means for ensuring the selection sequencies 2-1-2 and 4-5-4.

Indexing motion of the toothed wheels 78, 79 is translated into longitudinal adjustment of cables 117, 118 respectively connected with cable levers 69, 71 through edge cam 68, rotation of such wheels causing rotation of the indexing shaft and thus angular adjustment of the edge cam.

By providing appropriate cam profiles 119, 121 on the edge cam for respective cooperation with cam follower lugs 72, 73 on cable levers 69, 71 respectively, the angular position of the levers can be adjusted and the cables connected therewith adjusted accordingly, thus to control the change speed gear to which the control is applied.

Suitable guide channels to receive the cables 117, 118 are provided in a block formed integrally with the housing base, the ends of the cable levers 69, 71 being formed to receive the cable nipples in conventional manner, the housing base being provided with a cable and cable nipple entry slot 126 for cable attachment.

The outer face of toothed wheel 78 and the adjacent surface of the housing top 97 are provided with indicator means showing the gear selected, such means being illustrated in Fig. 5 and being seen to comprise a radial recess 127 in the face of the toothed wheel and legends 128 appropriate to the individual gears adjacent the periphery of that part of the toothed wheel which extends through the housing top.

Finally, the housing base 91 is provided with a mating part of a universal mounting clip arrangement adapted to allow of the fixing of the trigger control in any requisite position on the bicycles.

As can best be seen from Fig. 8, the clip arrangement 129 comprises an annulus 131 having a radial slot 132 in the outer face thereof to receive a radially disposed mounting clip 133, the inner periphery of the annulus being serrated, as at 134, for cooperative engagement with a complementary formation 135 provided integrally with the housing base and at the outer face therof. The clip arrangement is secured by a bolt 136 engaged with the housing base 91.

The invention is not restricted to the embodiments hereinbefore described, since alternatives will readily present themselves to one skilled in the art.

Thus, for example, whilst the indexing mechanism hereinproposed is disclosed specifically in the context of trigger controls for such as bicycle 3 or 5-speed change-gear hubs, such mechanism may well be of advantageous application in connection with multispeed gear hubs having other than 3 or 5 gear selections or indeed in other contexts.

Furthermore' the mechanism is not limited to arrangements wherein the indexing is along an arcuate path, since modifications will readily present themselves to one skilled in the art such as would render the same of application to linear indexing.

Similarly, the step-wise release mechanism may be readily adapted for linear operation.

Claims (22)

1. In or for a trigger control for a bicycle and like change speed gear, an indexing mechanism comprising an indexing wheel a control plate mounted coaxially with the said indexing wheel for angular motion relative thereto, an indexing member carried by the control plate and movably mounted thereon for adjustment angularly thereof, and selectively cooperable drive formations on the indexing wheel and indexing member, respectively, the drive formations being mutually engageable on adjustment of the indexing member from a datum position relative to the control plate in an appropriate sense and being adapted, upon continued movement in the same sense to transmit a drive motion to the indexing wheel, the mechanism further comprising return means biasing the indexing member to the said datum position relative to the control plate when displaced therefrom.

2. The indexing mechanism as claimed in claim 1, wherein the indexing lever is pivotally secured to the control plate as a gener ally radial extension thereto, being pivotable about an axis parallel to the rotational a xis of the control plate,and the selectively cooperable drive formations comprise a formation on the indexing member for selective engagement with one of a plurality of cooperable formations on the indexing wheel.

3. The indexing mechanism as claimed in claim 1 or 2, wherein the drive formations on the indexing wheel are provided on the periphery thereof.

4. The indexing mechanism as claimed in any one of the preceding claims, further including resilient means resisting displacement of the control plate from a datum position thereof.

5. The indexing mechanism as claimed in any one of the preceding claims, wherein the return means biasing the indexing member to the datum position relative to the control plate includes a fixed abutment member engageable by the indexing member.

6. The indexing means as claimed in any one of claims 1 to 4, wherein the return means biasing the indexing member to the datum position includes a resilient means provided between the indexing member and control plate.

7. The indexing means as claimed in claim 6, wherein the resilient means extends radially of the control plate and is disposed within the indexing member, said resilient means being operable to resist relative movement between the control plate and indexing member in each of two opposite directions.

8. The indexing mechanism as claimed in any one of claims 1 to 5, wherein the indexing wheel is adjustable in increments in a first direction against resilient restraint means, and further including release means operable for the controlled movement of the indexing wheel in a second direction opposite to said first direction, the release means comprising plural arrays of detent formations arranged in adjacent parallel disposition on the indexing wheel, at least one of the individual detents of one array being in laterally offset disposition in relation to the spaced lugs on the release member corresponding detent of another array, a release member each for selective cooperation with a respective one of the said arrays, and a restraint means resiliently resisting motion of the release member.

9. The indexing mechanism as claimed in claim 8, wherein the plural arrays of detent formations are provided at the periphery of the indexing wheel, these being an array at each respective face of said wheel.

10. The indexing mechanism as claimed in claim 9, wherein the spaced lugs are arranged in opposed disposition and are separated by a distance such as will ensure engagement with one or other detent formation at all times.

11. A trigger control for a bicycle and like change speed hub including an indexing mechanism as claimed in any one of the preceding claims 1 to 5.

12. A trigger control as claimed in claim 11, wherein the indexing wheel is adjustable in increments in a first direction against resilient restraint means, and further including release means operable for the controlled movement of the indexing wheel in a second direction opposite to said first direction, the release means comprising plural arrays of detent formations arranged in adjacent parallel disposition on the indexing wheel, at least one of the individual detents of one array being in laterally offset dispostion in relation to the corresponding detent of another array, a release member, spaced lugs on the release member, each for selective cooperation with a respective one of the said arrays, and a restraint means resiliently resisting motion of the release member.

13. A trigger control as claimed in claim 12, wherein the plural arrays of detent formations are provided at the periphery of the indexing wheel, there being an array at each respective face of said wheel.

14. A trigger control as claimed in any one of claims 11 to 13 including a housing within which the indexing mechanism is mounted for angular motion therein, the indexing member extending outwardly from such housing through an elongate slot in the periphery thereof and the resilient means biassing the indexing member to the datum position comprising a spring extending between and connected with the control plate and the said housing.

15. A trigger control as claimed in any one of claims 11 to 14 further including return means resisting displacement of the indexing wheel from a datum position, said return means comprising a spring extending between and connected with the indexing wheel and said housing.

16. A trigger control as claimed in claim 12, wherein the release member is mounted in the housing for reciprocatory motion against the restraint of a resilient means.

17. A trigger control as claimed in claim 11, wherein the indexing wheel is selectively adjustable in increments in either direction of rotation thereof, the control further including spring loaded location means engageable and cooperable with the indexing wheel to retain such wheel in a adjusted angular disposition.

18. A trigger control as claimed in claim 17, further including cam means arranged coaxially with the indexing wheel for rotation therewith and plural cam followers pivotally mounted for oscillatory movement about a common axis arranged in spaced parallel dispostion relative to the rotational axis of the indexing wheel, the cam followers each being connectable with a respective gear control cable, the cam means providing separate cam profiles for the respective cam followers, the cam profiles being so adapted and and arranged to provide for predetermined sequential displacement of the gear control cables, according to the incremental angular adjustment of the indexing wheel and gear change requirements.

19. A stepwise release means for the indexing mechanism of a bicycle or like change speed gear trigger control, which indexing mechanism includes an indexing body adjustble in increments in a first direction against resilient restraint means, the release means comprising plural arrays of detent formations arranged in adjacent parallel disposition on the indexing body, at least one of the individual detents of one array being in laterally offset disposition in relation to the corresponding detent of another array, a release member, spaced lugs on the release member, each for selective cooperation with a respective one of the said arrays and a restraintmeans resisting motion to the release member.

20. In or for a trigger control for a bicycle or like change speed gear, an indexing mechanism substantially as hereinbefore described with reference to and as illustrated in Fig. 3 or 6 of the accompanying drawings.

21. A trigger control for a bicycle or like change speed gear substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 4 or in Figs. 5 to 10 of the accompanying drawings.

22. A stepwise release means for the indexing mechanism of a bicycle or like change speed gear trigger control, substantially as herein before described with reference to and as illustrated in Fig. 4 of the accompanying drawings.