GB2496671A - Height adjustment device for a cycle handlebar - Google Patents

Abstract

A height adjustment device has a collar 3 for locating around a region of a support tube, such as a steerer tube 2, an elongate extension shaft 1 slidably mounted at the collar 3 to which a handlebar stem (50, figure 4) may be mounted. The extension shaft 1 is slidable via an actuator mechanism that is controlled by a remote trigger, and is capable of axially extending from the support tube 2 and collar 3 to raise the height of the handlebar. The extension shaft 1 may be biased towards one end of its travel by means of a gas spring 10. Also disclosed is a device for adjusting the headset, comprising a turn-down nut 33 threadingly engaged with the collar 3 and adapted to engage the upper headset bearing 32. A castellated outer periphery (37, figure 7) is engaged by a locking pin (35, figure 7) when bearing adjustment is complete.

Description

HEIGHT ADJUSTMENT MECHANISM FOR A CYCLE

The present invention relates to a height adjustment mechanism for a handlebar of a cycle.

Sd that a bicycle maybe matched to the rider it is beneficial that a number of parts of the bicycle are adjustable in their position on the bicycle frame. In particular the seat and the handlebars are moved to suit the size of the rider and their reach from seat, pedals and handlebar. The adjustments are commonly carried out for a rider when static; however this is a compromise given that when a bicycle is in use the needs of the rider may be variable during the ride. This is most evident with the application of Mountain Bikes when the terrain, attitude and velocity of the bicycle mean that the rider chooses to move about relative to the frame and thus the handlebar is fixed and therefore physically limiting.

The provision for an in-ride dynamically adjustable seat height has been enabled with the advent of locking spring-damper seat posts, such as that disclosed by WALSH AUSTIN A US 2011187166 (Al) -Bicycle Seat Height Adjusting Assembly -wherein the sprung load from the spring-damper up onto the seat is actuated remotely and conveniently. A further adjustable seat height device is disclosed in US 2011/0257848. However the provision for a dynamically adjustable handlebar height adopting the mechanics of this solution is yet to be disclosed. Any solution must be mechanically suitable to comply with the forces imposed upon it in practice and also in compliance with prevalent standards. The European Standard EN 14766 stipulates lateral and forward bending and torsion loads from the handlebar to stem and steerer tube. The axially constrained spring-damper solutions disclosed for use on seat height have not been applicable for use on handlebar height because of the lesser mechanical demands for the saddle to withstand, hence the use of a slot and key to maintain alignment that is adequate for the seat height adjusting assembly is not for the prevailing standards and service duty required of a dynamically adjustable handlebar height mechanism.

The provision for a dynamically adjustable handlebar height has been shown with hinged stems, such as that disclosed by the "EZ Ride" system, patent status unknown. This device shows a hinging stem having a parallelogram type structure. Such a structure is of benefit because the preferred angled attitude of the handlebar remains unaltered during the articulation of the stem.

A hinging stem moves through an arc, thus when the handlebar is at fill height the centreline of the handlebar may pass very close to the axis of the steer tube, the converse being true for when the handle bar is down and the stem is horizontal and thus the handlebar is moved forwards of the pivot point of the front wheel by the radius of the are traversed by the hinging stem. A drawback of this variation of handlebar centreline to steerer tube eentreline is that it imposes a variance in the torque requirement to turn the bicycle front wheel and hence a variable sensation of feel and response.

A further drawback of the hinging stem is that the hinging and the parallelogram system impose bulky features additional to a conventional stem to steerer tube fitment in the zone of the stem directly iii front of the rider.

Another system of handlebar height adjustment is provided by the "Easy-Up" marketed by Satori, patent DE20200501 5145W. The "Easy-Up" provides an extension tube which fits telescopically within the steerer tube, this extension tube slides within a coupling clamped to the top of the steerer tube and the handlebar stem is bolted instead to the top of the extension tube. 1-leight is adjusted by sliding the extension tube up or down and then using an over-centre clamp to squeeze the coupling onto the extension tube to lock it in position.

A groove in the extension tube and a false woodruff key in the coupling inhibit any rotation as the extension tube is being moved up or down between adjustments. This layout retains the same fore and aft relative location of the handlebar to the axis of the steerer tube, however the "Easy-Up" does not provide in-ride dynamically adjustable handlebar height and the clamp on the coupling must be engaged at all times to comply with EN14766.

The present invention provides a conveniently operated height adjustable assembly for a handlebar stem or saddle that may be adjustable dynamically as a user rides the cycle.

According to a first aspect of the present invention there is provided a handlebar height adjustment device for adjusting the height of a handlebar of a cycle, the device comprising a collar for locating externally around a region of a support tube to which the device is attachable, the collar having a first clamp to secure the collar to the support tube at a first position; an elongate extension shaft slidably mounted within the collar and being coaxially aligned with the support tube such that the extension shaft can slide axially relative to the collar and support tube; a second clamp to secure internally to a second position of the support tube and to provide an anchorage from which the extension shaft can slide; an actuator mechanism capable of being housed internally within the support tube andlor the extension shaft and operable to cause the extension shaft to slide axially relative to the collar and support tube; and a remote trigger positionable remotely and externally of the support tube and/or the extension shaft, the remote trigger being provided in communication with the actuator mechanism to control the axial sliding movement of the extension shaft relative to the collar and the support tube; wherein the extension shaft over a region of its length has an outer surface cross sectional profile that is non-circular and/or comprises a plurality of discontinuities in the outer surface.

The trigger may be provided in communication with the actuator mechanism via any suitable interconnection including a cable, a tube or conduit allowing the flow of a fluid or remote wireless type connections in which there is no physical connection between the two components.

Optionally, the communicationlconnection between trigger and the actuator mechanism may comprise any one of the following: a wire cable such as a Bowden type cable which has wire sheathed within a cable, the wire making a flexible yet physical link between the trigger and the actuator mechanism; a hydraulic cable which has a nominally incompressible fluid retained within a sealed cable to transmit force between the trigger and the actuator mechanism; pneumatic cable which has a gas retained within a sealed cable to transmit force between the trigger and the actuator mechanism; an electric cable where the trigger (a lever) operates a switch used to make (or break) electrical signal to a solenoid valve or similar that acts upon or provides the function of actuating the mechanism within the steerer tube and/or extension shaft; a light cable wherein the trigger (a lever) operates an optical switch used to make (or break or modulate) optical signal from transmitter to receiver via fibre optic cable such that the receiver can convert the signal to an output signal that may operate a solenoid valve or similar that then acts upon or provides the ifinction of actuating the mechanism within the steerer tube and/or extension shaft; a remote transmit and receive wherein a signal, such as infrared, radio or other electromagnetic radiation, or sound is generated wherein its transmission on or off or its modulation is provided by the trigger (a lever) such that a receiver can convert the signal to an output signal that may operate a solenoid valve or similar that then acts upon or provides the function of actuating the mechanism within the steerer tube and/or extension shaft.

Reference within this specification to support tube includes a steerer tube and/or a tube supported or permanently or temporarily attached to the steerer tube.

Reference within this specification to the actuator mechanism encompassed those components that enable the extension shaft to move axially relative to the collar and the support tube and also to those components that lock the extension tube axially relative to the collar and the support tube between adjustments. Advantageously and to reduce the weight of the present device, the lock component that prevents axially movement of the extension tube is a valve and the hydraulic/pneumatic fluid housed within the actuator mechanism.

Preferably, the actuator mechanism comprises a pneumatic and/or hydraulic piston arrangement. Preferably, the piston arrangement comprises a lock valve to prevent flow of a fluid within the arrangement and to lock axially the extension shaft relative to the support tube. Preferably, the arrangement comprises a lock pin moveably mounted within the support tube and/or the extension shaft, the moveable lock pin configured to control flow of fluid within the actuator mechanism. The valve and pin form a part of the actuator mechanism that is configured to lock sliding movement of the extension shaft relative to the support tube. Importantly the lock component(s)/actuator(s) of the actuator mechanism is located internally within the support tube and/or extension shaft and is controlled by the trigger. As will be appreciated the internal lock component(s) may comprise all mariner of components specific to the type of actuator mechanism employed.

Preferably, the device further comprises an adjustable brace mounted towards to one end of the collar and capable of extending axially away from the collar. Preferably, the device further comprises a lock pin externally mounted at the collar and slidably moveable to engage the brace and prevent the brace from moving axially at the collar. Optionally, the brace comprises external castellations and the lock pin is configured to engage the castellations and prevent the brace being rotated relative to the collar.

Preferably, the device further comprises a bush mounted internally of the collar to sit between the extension shaft and the collar, the bush comprising axially extending grooves formed at an internal facing surface.

Optionally, the device further comprises a bias actuator mounted within the support tube and/or the extension tube to bias axially the extension shaft in one direction relative to the support tube.

Optionally, the trigger is a lever, button or switch. Preferably, the trigger comprises a mount to mount the trigger at a handlebar.

In one embodiment, the device is comprised of an Extension Shaft at the top of which is a Grip Sleeve to which the rider bolts on the pre-existing handlebar stem. At the bottom of the Extension Shaft is fixed a Cylindrical Bush that performs as a plain bearing when the Extension Shaft is located within the steerer tube. The Extension Shaft is guided by a Female Bush which is sited within the Coupling that clamps to the top of the steerer tube.

A pair of Adjusters is included in the Coupling; these also pass through the Female Bush and run against offset sides of the Extension Shaft. The Adjusters have bearing faces made of low friction material, such as PTFE, that when bearing upon the sides of the Extension Shaft take up any clearance in the fit of the Extension Shaft to the Female Bush. The preferred design of Extension Shaft is a splined shaft, the number of splines; their length and the material of manufacture, such as Aluminium Bronze are such that the bending and torsion loads in practice and those as required by EN14766 maybe satisfactorily withstood. For the Extension Shaft to Female Bush design to be mechanically fit for use the materials of construction and the area under shear stress must be adequate, the preferred material for the Extension Shaft is Aluminium A6061 T6 with a hard anodised finish and a PTFE low friction coating treatment, this provides sufficient strength for the bending loads when the shaft is at full extension, is a low mass metal to keep the overall weight of the assembly down. However it is insufficiently strong material for a single keyway of length and depth limited by the physical constraints of fitment within the I and 118th inch Steerer Tube and the Collar mounted to it, hence the solution is to have multiple areas about the circumference of the shaft under shear, the preferred design being a splined shaft having a cross sectional castellated external surface. An Extension Shaft to Female Bush may alternatively provide multiple shear areas by use of a ribbed and grooved shaft that mates into a matching bush, such as shaft having semi-circular grooves paired to a re-circulating ball bush or the function of a bush that is provided solely through matching circular rods. Alternatively the Extension Shaft to Female Bush may provide sufficient area under shear to be mechanically suitable by having a non-round shaft, such as a hexagon, fitting to a matching non-round bore in the Female Bush.

According to the subject invention, the extension shaft is configured to provide multiple regions where loading and shear forces can be transmitted to the support tube via the adjustment device. Accordingly, the extension shaft comprises a non-circular outer surface cross sectional profile andlor has a plurality of diseontinuities in the outer surface. The term discontinuities' refers to gaps, slots, ridges, ribs, recesses, troughs, indentations, projections in the outer surface of the extension shaft to act against and abut an alternate and opposed gaps, slots, ridges, ribs, recesses, troughs, indentations, projections formed at the collar and in particular a mounting bush extending between the collar and the extension shaft. An example of this is an extension shaft with a castellated cross sectional profile and where the mounting collar or preferably the bush comprises a corresponding castellated profile such that the surfaces of the shaft set of rib and troughs can interlock with the opposed surfaces of the bush set of ribs and troughs acting to suitably transfer the loading and shear forces during use.

Preferably, the outer surface cross sectional profile of the extension shaft is castellated such that the eitcnsion shaft comprises axially extending ribs separated by axially extending troughs. Optionally, the outer surface cross sectional profile of the extension shaft is polygonal, oval or comprises a plurality of inwardly and outwardly extending curved regions. Optionally, the extension shaft comprises a plurality of elongate slots extending axially along a region of the extension shaft to create gaps in the outer surface of the extension shaft.

Preferably, the bush comprises an internal facing surface cross sectional profile that is castellated and configured to mate with the castellated profile of the extension shaft such that the castellations interlock. Optionally, the bush comprises an inner facing surface cross sectional profile that is polygonal, oval or comprises a plurality of inwardly and outwardly extending curved regions to correspond and mate with the outer surface cross sectional profile of the extension shaft. Optionally, the bush comprises a plurality of projections to be received within each of the plurality of slots of the extension shaft.

Optionally, the discontinuities extend over substantially the frill length of the extension shaft. Optionally, the present device does not comprise a bush and the internal facing surface of the collar is internally profiled as described with reference to the bush.

The Extension Shaft and the stem and handlebar, are driven up within the steerer tube by use of a Spring-Damper, preferably a Gas Spring unit. The preferred orientation of the Gas Spring has the Rod beneath the body of the Gas Spring; the bottom of this Rod is mechanically gripped to the internal diameter of the base of the steerer tube by use of a Steerer Tube Grip component. The preferred design of Steerer Tube Grip is of taper clamp design, a commonly used alternative to the "Star Fangled Nut" that is used to tighten Head Sets. The Gas Spring body fits concentrically within the Extension Shaft and they are fixed together at the top of the assembly.

The Gas Spring is a locking type, this having a Locking Valve feature within the gas spring that may be actuated remotely. Actuation of the Locking Valve is commonly through the Rod, this being hollow thus enabling an Actuator Connection at its exposed end. The preferred actuator type is a lever that articulates using wire or hydraulic cable a Locking Valve Pin that moves via the hollow bore of the Rod raising or lowering the Locking Valve. When the Locking Valve is raised hydraulic fluid may pass from one side of the Locking Valve to the other, thus the Gas Spring unlocks enabling movement of the Gas Spring body relative to it's rod under internal gas pressure. The preferred orientation of the Gas Spring causes the handlebar to be pushed upward when the gas spring is unlocked.

When the rider wants to lower the handlebar the Gas Spring is unlocked and the rider pushes down on the handlebar against the load of the Gas Spring, re-engaging the lock when the desired height is reached. When the rider wishes to raise the handle bar the reverse operation is done. The locking characteristic of the Gas Spring fixes the handlebar vertical position between operations of the lever.

The Head Set of the bicycle has the Top Bearing and Bottom Bearing clamped across so that bearing clearance and play are minimised. The conventional practice is to use a "Star Fangled" nut that grips to the internal diameter of the Steerer Tube and when tightened pulls down on the Steerer Tube, moving the Coupling towards the Top Bearing Cover, so reducing the Top Bearing Clearance. For the present invention this function may be achieved by firstly bolting tightly the Coupling to the Steerer Tube with the bearing clearance as small as is practical and then using a Turn-down Nut that is fine-threaded to the base of the coupling to screw down against the Top Bearing. To prevent the Turn-down Nut from unscrewing when the bicycle is in use the Turn-down Nut is then fixed in place by use of a Lock Pin that passes through co-linear guide holes in the coupling to latch against Latching Grooves in the circumference of the Turn-down Nut. Should the bearing clearance increase in use then it is a simple matter of pulling up the Locking Pin, turning further the Turn-down Nut until the fit is again tight and then re-locking in place the Locking Pin.

The range of Height Adjustment of the present invention is infinite, between zero and the limitation of the stroke of the Gas Spring. For the example according to the preferred embodiment described herein the stroke of the Gas Spring is 80mm and found to be sufficient within the needs of the rider and the mechanical constraints of standard EN14766. --9-

Objectives of the present invention enable the infinite adjustment of the handlebar height within the known stroke of the assembly such that the rider may in a convenient manner make height changes whilst riding the bike.

The above and other benefits of the present invention will now be described inmore detail, by way of example only, with reference to the accompanying drawings in which; Fig.I is a partial front view of the present invention inserted into the head set and forks of a bicycle.

Fig.2 is a partial section view denoted by A-A in Fig.l.

Fig 3 is an exploded isometric view of the present invention.

Fig 4 is an isometric view and schematic with Stem and Lever of the present invention.

Figs. 5 and 6 are side views of the present invention fully down and fully extended.

Fig.7 is a three dimensional view of the Coupling.

Fig.8 is a partial section view of the Coupling.

Fig. 9 is a partial section of an alternative embodiment of the present invention.

Detailed Description of the Preferred Embodiment:

Referring to Figs. 1, 2 and 3 and according to one embodiment, the height adjustment device comprises an Extension Shaft 1, a Female Bush 2, a Coupling 3, a Spring-Damper 4 and a Locking Valve 5. 10..

The Spring-Damper 4 for the preferred embodiment is a Gas Spring 10. A Gas Spring contains a pressurised gas that is the source of the spring load. Gas Springs are commercially available in many configurations, for the preferred embodiment the type is a rigid locking Gas Spring where the Gas Spring 10 comprises a Gas Spring Body 11, a Rod 12, a Locking Valve 5, a Locking Valve Pin 13, a Gas Chamber 14, a Piston 15 and Hydraulic Fluid 16.

The Gas Spring Body 11 contains pressurised gas in a Gas Chamber 14 that exerts load upon an axially mobile Piston 15. The Piston 15 seals between its perimeter and the internal diameter of the Gas Spring Body 11 by use of a trapped 0 Ring, Quad Ring or similar sealing piston ring. Given the axial mobility of the Piston 15 the compressed gas load on the Piston 15 is transferred onto the Hydraulic Fluid 16 that is beneath it and separates the pressurised gas from direct contact with the Hydraulic Fluid 16. The load on the Hydraulic Fluid 16 in turn exerts pressure upon the Rod Head 18 which may move axially and seals to the internal diameter of the Gas Spring Body 11 by use of a trapped 0 Ring, Quad Ring or similar sealing piston ring. The Rod 12 passes out of the base of the Gas Spring Body 11, via a Sealing Gland 28, to atmosphere and thus a load balance exists between any forces additionally exerted externally upon the Rod 12 and the pneumatic to hydraulic loads internally. With no additional external forces the consequence of the internal pneumatic pressure is to cause the Rod 12 to be pushed away from the Gas Spring Body 11. Close down of Locking Valve 5 prevents the Hydraulic Fluid 16 above the Rod Head 18 from physical communication with the hydraulic fluid beneath it, this closure of passage stops any fluid flow and so hydraulically locks in place the Rod Head 18.

The Gas Spring 10 is sized to fit concentrically within the Extension Shaft ito which the Gas Spring Body 11 is fixedly attached, this attachment being made by screwing a Threaded Boss 17 at the top of the Gas Spring Body 11 into the Top Cap 20 which also screws into a thread portion at the top of the Extension Shaft 1.

The Rod 12 is fixedly attached to the Steerer Tube 6 of the bicycle Forks 7 by use of the Steerer Tube Grip 21. The Steerer Tube Grip 21 is of the taper clamp design having wedge shaped Cheeks 23 that are forced outwards when the Bevelled Plate 24 is screwed towards the Upper Plate 25 by the Rod 12 being screwed into the Steerer Tube Grip 21, thus gripping the internal diameter of the Steerer Tube 6.

The cycle to which the present device is mounted comprises Handlebars 40 and a Stem 50.

The Stem 50 has a clamp that is sized to grip and retain the Handlebars 40 and a second clamp originally sized to grip to the Steerer Tube 6; this is commonly 1 and 1/8th inch diameter. The Stem 50 attachment point and thus Handlebars 40 are affixed to the top of the Extension Shaft I by clamping via the Grip Sleeve 22 that is sandwiched between Stem and the Extension Shaft 1. The Grip Sleeve 22 is a longitudinally slit tube of internal diameter size to be a transition fit to the outside diameter of the Extension Shaft I and of outside diameter nominally the same value as the Steer Tube 6, the Stem is clamped to the Grip Sleeve 22 and because this is slit it in turn reduces in diameter and grips to the Extension Shaft 1. The Extension Shaft 1 is a splined shaft and the Female Bush 2 is a matching splined bush. For this embodiment a 25 x 21 x 6 splines to European Standard D1N5463 was used, this sizing providing sufficient stressed area and volume when using Aluminium Bronze C104 material for the Female Bush 2 of length 20mm and Aluminium A606 1 T6, tensile strength 1 7OMIPa, for the Extension Shaft 1 to comply with European standard EN 14766 To take up any clearances in the fit of Extension Shaft 1 to Female Bush 2 there are two offset Adjusters 23 used, the Adjusters 23 are grub screws with insert Noses 26 made of low friction material, such as PTFE. The Adjusters 23 are screwed in through tapped Holes 27 in the sides of the Coupling 3 and Female Bush 2 and bear upon the sides of the Extension Shaft 1. At the base of the Extension Shaft 1 fits Cylindrical Bush 29 that is retained in place by Spring Clip 39. The Cylindrical Bush 29 is of sintered bronze and provides a plain bearing running fit to the internal diameter of the Steerer Tube 6 enabling smooth linear movement of the Extension Shaft 1, the Spring Clip 39 fits into a machined grooved slot at the base of the Extension Shaft 1.

In use, the Rod 12 is free to move axially within the Gas Spring 10 and the consequence of the internal gas pressure is to cause the Rod 12 to be pushed away from the Gas Spring Body 11, however with the base of the Rod 12 is fixedly attached to the Steerer Tube 6 the resultant action is to force up the Gas Spring Body 11 which in turn being fixedly attached to the Extension Shaft 1 causes this the Extension Shaft ito move upwards. Movement of the Extension Shaft 1 results in movement of the co-attached Stem 50 and Handlebars 40.

When the user wishes to stop axial movement of the handlebars this is done by closure of the Locking Valve 5. The locked position can be at any position within the range of movement of the Rod 12, referring to Figs. 5 and 6.

The bicycle rider may carry out the actuation of the Locking Valve 5 by use of a Lever 60 that is conveniently remote from the Gas Spring 10. Movement of the remote lever causes a Wire 61 within a Bowden type Cable 62 via attachment at the Actuator Connection 19 to move a Locking Valve Pin 13 within the hollow bore of the Rod 12 and thus raising or lowering the Locking Valve 5. When the Locking Valve 5 is raised hydraulic fluid may pass from one side of the Locking Valve 5 to the other, the Gas Spring 10 hydraulically unlocks enabling movement of the Gas Spring Body 11 relative to it's rod under internal gas pressure and any external loads. When the (las Spring 10 is unlocked and no external forces applied to the Rod 12 then the handlebar is pushed upward by the internal gas pressure. When the rider wants to lower the handlebar the Gas Spring 10 is unlocked and the rider pushes down on the handlebar with a force against and in excess of the load of the Gas Spring 10. When raising or lowering the handlebar at the instant the desired height is reached actuation of the Locking Valve 5 is ceased and the Locking Valve 5 closes.

With Reference to Figs. 7 and 8. when installing the present device to the bicycle the Top Bearing Clearance 31 of the Head Set 30 of the bicycle is to be minimised by moving the Coupling 3 close the Top Bearing Cover 32 and so reducing the play and arriving at the correct fit of the bearing set. To achieve this the first action of the user is to clamp the Coupling 3 to the Steerer Tube 6 by bolting across Clamping Flange 34 with the Top Bearing Clearance 31 as small as is practical, this is then further reduced using a Turn-down Nut 33 that is fine-threaded to the base of the Coupling 3 to screw down against the Top Bearing Cover 32. Rotation anti-clockwise of the Turn-down Nut 33 causes it to move downwards, a full rotation moving it by one pitch of the thread. Because the Coupling 3 has been clamped to the Steerer Tube 6 downward movement of the Turn-down Nut 33 causes load down upon the Top Bearing Cover 32 and concurrently pull up of base of the Steerer Tube 6 on the Bottom Bearing 38 and hence closure of any existing play in the bearings of the Head To prevent the Turn-down Nut 33 from unscrewing when the bicycle is in use the Turn-down Nut 33 is fixed in place by use of a Locking Pin 35 that passes through co-linear Guide Holes 36 in the Coupling 3 to latch against Latching Grooves 37 in the circumference of the Turn-down Nut 33. Should the Top Bearing Clearance 31 increase after use of the bicycle then it is a simple matter of pulling up the Locking Pin 35, turning further anti-clockwise the Turn-down Nut 33 until the fit is again tight and then re-locking in place the Locking Pin 35.

Fig. 9 illustrates an alternative embodiment of the Spring-Damper 4 and associated locking mechanism described with reference to Figs, 1 to 8. According to the ftirther embodiment the Spring-Damper 4 function is provided by a Compression Spring 70, a Gear Wheel 71, a Gear Wheel Block 72, Rack 73, Locking Gear Pin 74, Rack Clamp 75, Extension Shaft 1B, and a Grip Sleeve 22B.

The Rack 73 is fixedly attached to the Steerer Tube 6 by Rack Clamp 75; this clamp may be composed of the similar parts to the Steerer Tube Grip 21 of Fig. 2. The Extension Shaft lB and hence stem and handlebars clamped to it via Grip Sleeve 2211, are pushed upwards by Conipression Spring 70 pressing between the base of the Gear Wheel Block 72 that is fixedly attached to the internal diameter of the Extension Shaft 1 B and the Rack Clamp 75.

A Gear Wheel 71 is free to rotate in Gear Wheel Block 72 and rums in enmeshed gear against the teeth of the Rack 71. The mechanical friction of the Gear Wheel 71, in both rotation and enmeshment against the rack 73, provides damping against the Compression Spring 70. The height to which the handlebar rises or is pushed down may be locked by engagement of the Locking Gear Pin 74 into the teeth of the Gear Wheel 71.

Another alternative embodiment would be for the Extension Shaft I to be used in lieu of the Gas Spring Body 11, with the necessary Sealing Gland 28, Piston 15 and other Gas Spring parts including compressed gas and hydraulic fluid transferred into the Extension Shaft 1 and sized to suit.

Claims (1)

1. <claim-text>Claims: 1. A handlebar height adjustment device for adjusting the height of a handlebar of a cycle, the device comprising: a collar for locating externally around a region of a support tube to which the device is attachable, the collar having a first clamp to secure the collar to the support tube at a first position; an elongate extension shaft slidably mounted within the collar and being coaxially aligned with the support tube such that the extension shaft can slide axially relative to the collar and support tube; a second clamp to secure internally to a second position of the support tube and to provide an anchorage from which the extension shaft can slide; an actuator mechanism capable of being housed internally within the support tube and/or the extension shaft and operable to cause the extension shaft to slide axially relative to the collar and support tube; and a remote trigger positionable remotely and externally of the support tube and/or the extension shaft, the remote trigger being provided in communication with the actuator mechanism to control the axial sliding movement of the extension shaft relative to the collar and the support tube; wherein the extension shaft over a region of its length has an outer surface cross sectional profile that is non-circular and/or comprises a plurality of discontinuities in the outer surface.</claim-text> <claim-text>2. The device as claimed in claim 1 wherein the actuator mechanism comprises a pneumatic and/or hydraulic piston arrangement.</claim-text> <claim-text>3. The device as claimed in claim 2 wherein the piston arrangement comprises a lock valve to prevent flow of a fluid within the arrangement and to lock axially the extension shaft relative to the support tube.</claim-text> <claim-text>4. The device as claimed in claim 2 or 3 wherein the arrangement comprises a lock pin moveably mounted within the support tube and/or the extension shaft, the moveable lock pin configured to control flow of fluid within the actuator mechanism.</claim-text> <claim-text>5. The device as claimed in any preceding claim further comprising a bush mounted internally of the collar to sit between the extension shaft and the collar.</claim-text> <claim-text>6. The device as claimed in any preceding claim wherein the outer surface cross sectional profile of the extension shaft is castellated such that the extension shaft comprises axially extending ribs separated by axially extending troughs.</claim-text> <claim-text>7. The device as claimed in any one of claims 1 to 5 wherein the outer surface cross sectional profile of the extension shaft is polygonal, oval or comprises a plurality of inwardly and outwardly extending curved regions.</claim-text> <claim-text>8. The device as claimed in any one of claims Ito 5 wherein the extension shaft comprises a plurality of elongate slots extending axially along a region of the extension shaft to create gaps in the outer surface of the extension shaft.</claim-text> <claim-text>9. The device as claimed in claim 5 and 6 wherein the bush comprises an internal facing surface cross sectional profile that is castellated and configured to mate with the castellated profile of the extension shaft such that the castellations interlock.</claim-text> <claim-text>10. The device as claimed in claims and 7 wherein the bush comprises an inner facing surface cross sectional profile that is polygonal, oval or comprises a plurality of inwardly and outwardly extending curved regions to correspond and mate with the outer surface cross sectional profile of the extension shaft.</claim-text> <claim-text>11. The device as claimed in claim 5 and 10 wherein the bush comprises a plurality of projections to be received within each of the plurality of slots of the extension shaft.</claim-text> <claim-text>12. The device as claimed in any preceding claim further comprising an adjustable brace mounted towards to one end of the collar and capable of extending axially away from the collar.</claim-text> <claim-text>13. The device as claimed in claim 12 wherein the brace comprises internally facing screw threads operatively engaged with screw threads formed on an external facing surface of the collar.</claim-text> <claim-text>14. The device as claimed in claim 12 or 13 further comprising a lock pin externally mounted at the collar and slidably moveable to engage the brace and prevent the brace from moving axially at the collar.</claim-text> <claim-text>15. The device as claimed in claim 14 wherein the brace comprises external castellations and the lock pin is configured to engage the castellations and prevent the brace being rotated relative to the collar.</claim-text> <claim-text>16. The device as claimed in any preceding claim further comprising a bias actuator mounted within the support tube and/or the extension tube to bias axially the extension shaft in one direction relative to the support tube.</claim-text> <claim-text>17. The device as claimed in any preceding claim wherein the trigger is a lever, button or switch.</claim-text> <claim-text>18. The device as claimed in claim 17 wherein the trigger comprises a mount to mount the trigger at a handlebar.</claim-text>