AU721044B2

AU721044B2 - Shock damping bicycle handlebar stem

Info

Publication number: AU721044B2
Application number: AU75489/96A
Authority: AU
Inventors: Barry Aarons
Original assignee: FIXTRONICS Pty Ltd
Current assignee: FIXTRONICS Pty Ltd
Priority date: 1995-12-19
Filing date: 1996-12-19
Publication date: 2000-06-22
Anticipated expiration: 2016-12-19
Also published as: AU7548996A

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

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a a oo *ooo Name of Applicant: Actual Inventor: Fixtronics Pty Ltd Barry Aarons Address for Service: OBERINS ARTHUR ROBINSON HEDDERWICKS Patent and Trade Mark Attorneys 530 Collins Street Melbourne, Victoria, 3000, Australia Invention Title: Shock damping bicycle handlebar stem The following statement is a full description of this invention, including the best method of performing it known to me: 1 rja/docs/300301168 SHOCK DAMPING BICYCLE HANDLEBAR STEM The present invention relates to bicycle handlebar stems and more particularly to shock damping bicycle handlebar stems.

Conventional bicycle handlebar stems rigidly link the handlebars to the fork and front wheel so that shocks induced by the surface being overridden are transmitted to the body of the cyclist particularly, the upper body with minimal attenuation by compression of the front tyre. The exposure of the cyclist's body to repetitive shock during rides over extended periods and/or over uneven surfaces can hasten the onset of fatigue and, at the worst, induce pain or discomfort.

There have been various arrangements proposed to provide shock damping handlebars to minimise the frequency and/or amplitude of shock transmitted from bicycle to cyclist through the handlebars. Previously proposed arrangements have typically comprised a linkage between the handlebars and the fork post that allows the handlebars to pivot and some type of resilient element to damp the pivoting motion. A 15 particular disadvantage of pivoting linkage arrangements is that front wheel shocks induce rotation of the handlebars about the pivot axis. The rearward component of this pivoting motion is unnatural and ergonomically undesirable as it introduces additional stresses on the cyclist's body. In additional to being cumbersome, complex and costly to manufacture, many of the previously proposed arrangements have been specifically :0 designed to allow the handlebars to have only a limited degree of movement so as to preserve the precision and immediacy of the command of the handlebars over the wheel, minimise roll of the handlebars about the longitudinal axis of the bicycle frame, and minimise the ergonomically adverse effects of the pivoting motion. Consequently, the degree of shock damping these arrangements have been able to provide is limited.

Thus, previously proposed shock damping handlebar arrangements have proved to be of little value for reducing the shocks to which cyclists are exposed through the handlebars.

According to a first aspect of the present invention, there is provided a shockdamping handlebar stem for a bicycle, comprising damping means for resiliently interconnecting a fork post and a handlebar support member, said damping means being constructed and arranged to permit downward and upward movement of said handlebar support member relative to said fork post in response to shock encountered while the bicycle is in use such that downward movement of said handlebar support member is damped and occurs in a linear path.

The linear path of movement of said handlebar support member may be such that downward movement of said handlebar support support member is inclined away from said fork post and upward movement of said handlebar support member occurs in a linear path inclined toward said fork post.

According to a first embodiment of the first aspect of the present invention, there is provided a shock damping bicycle handlebar stem, comprising damping means for resiliently interconnecting a fork post and a handlebar support member preferably, a handlebar clamp said damping means comprising an outer tube connected to the fork post and an inner member connected to the handlebar clamp, said inner member being coaxially mounted inside, and adapted to telescope with respect to, said outer tube while under pretension by a spring such that downward telescopic movement occurs in 15 a linear path.

The downward telescopic movement of the inner member may be inclined away from said fork post. Preferably, the outer tube of damping means is inclined to the fork post at an angle in the range of 5 to 20 degrees such that the lower end of the outer tube is forward of the upper end of the outer tube. The inclination of the outer tube of the damping means in this preferred embodiment is intended to confine the range of o .movement of the handlebars during shock damping within natural limits by specifically °°ooo inhibiting any ergonomically undesirable rearward component of motion.

When a bicycle with this arrangement is subjected to a front wheel shock the cyclist's natural motion will cause the handlebars to be pushed downward which in turn will cause the handlebar clamp to move downward in a linear path that is inclined away from the fork post. During the downward motion the inner member connected to the handlebar clamp slides telescopically in the outer tube and compresses the pretensioned spring which absorbs a portion of the downward force imposed upon the arrangement to damp and slow the downward movement of the handlebars. When the cyclist releases downward force on the handlebars, the compressed pretensioned spring exerts a reactive upward force on the inner member connected to the handlebar clamp that urges the handlebars upward to return to their initial position- According to a second embodiment of the first aspect of the present invention, there is provided a shock damping bicycle handlebar stem, comprising damping means for resiliently interconnecting a fork post and a handlebar support member preferably, a handlebar clamp said damping means comprising an outer tube connected to the fork post and an inner member connected to the handlebar clamp, said inner member being coaxially mounted inside, and adapted to telescope with respect to, said outer member such that downward telescopic movement occurs in a linear path, said damping means further comprising a pretensioned spring and an elastomeric member to damp downward movement of said handlebar clamp. Preferably, said spring is coiled around the outer surface of, and mounted coaxially with respect to, said elastomeric element.

The downward telescopic movement of the inner member may be inclined away from said fork post. Preferably, the outer tube of damping means is inclined to the fork 15 post at an angle in the range of 5 to 20 degrees such that the lower end of the outer tube is forward of the upper end of the outer tube.

When a bicycle with this arrangement is subjected to a front wheel shock the cyclist's natural motion will cause the handlebars to be pushed downward which in turn will cause the handlebar clamp to move downward in a linear path that is inclined away from the fork post. During the downward motion the inner member connected to the handlebar clamp slides telescopically in the outer tube and compresses the pretensioned spring and the said elastomeric member, each of which absorbs a portion of the downward force imposed upon the arrangement to damp and slow the downward movement of the handlebars. When the cyclist releases downward force on the handlebars, the compressed pretensioned spring exerts a reactive upward force on the inner member connected to the handlebar clamp that urges the handlebars upward to return to their initial position.

Acording to a third embodiment of the first aspect of the present invention, in addition to the features descibed in relation to the first and/or second embodiments of the first aspect of the present invention, said spring is wound such that the coil density per unit length of the spring (ie. the pitch of the spring) decreases with distance from the top (or alternatively, the bottom) of the spring. Such a "progressive spring", which is well known to those who use springs, allows the effective stiffness of the spring to increase as it is compressed beyond a certain minimum distance by the downward movement of the said inner member. This change in stiffness occurs since, once the stated minimum distance of travel is reached or surpassed, the coils that were closest together when the handlebar support member was in a static position become compressed so as to come into contact with one another such that those coils can compress no further. Since the operatively compressible part of the spring will thereafter comprise only the coils of the spring that are not in contact with one another, the reduced length of the operatively compressible part of the spring causes an effective increase in the stiffness of the entire spring.

According to a second aspect of the present invention, there is provided a shock damping handlebar stem for a bicycle, comprising damping means for resiliently interconnecting a fork post and a handlebar support member, said damping means being 15 constructed and arranged to permit downward and upward movement of said handlebar support member relative to said fork post in response to shock encountered while the bicycle is in use such that downward movement of said handlebar support member is damped, said damping means further comprising an elastomeric element to damp upward movement of said handlebar support member by compression of said elastomeric element, said elastomeric element being arranged such that it is not compressed when said handlebar support member is in a static position. In substitution

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for, or preferably in addition to, said elastomeric element, said damping means may further comprise a spring to damp upward movement of said handlebar support member by compression of said spring, said spring being arranged such that it is not compressed when said handlebar support member is in a static position. Preferably, said spring is coiled around the outer surface of, and mounted coaxially with respect to, said elastomeric element.

According to an embodiment of the first and second aspects of the present invention, there is provided a shock damping bicycle handlebar stem, comprising damping means for resiliently interconnecting a fork post and a handlebar clamp, said damping means comprising an outer tube connected to the fork post and an inner member connected to the handlebar clamp, said inner member being coaxially mounted inside, and adapted to telescope with respect to, said outer tube while under pretension by a spring such that downward telescopic movement occurs in a linear path, said damping means further comprising an elastomeric element coaxially mounted inside said outer tube above said inner member to damp upward telescopic movement of said inner member by compression of said elastomeric element, said elastomeric element being arranged such that it is not under compression by the inner member when the inner member is in its initial or static position. Such an arrangement is preferred so that the elastomeric element is not degraded over time due to creep caused by compression of the elastomeric element by the inner member in its static position.

The downward telescopic movement of the inner member may be inclined away from said fork post. Preferably, the outer tube of damping means is inclined to the fork post at an angle in the range of 5 to 20 degrees such that the lower end of the outer tube is forward of the upper end of the outer tube.

15 When the cyclist releases downward force on the handlebars, the compressed pretensioned spring exerts a reactive upward force on the inner member connected to .the handlebar clamp that urges the handlebars upward to return to their initial position.

The elastomeric element acts as a damper to absorb a portion of the upward force imposed upon the arrangement by the return of the handlebars to their initial position.

It is thought that the inclusion of an elastomeric element and/ or a spring to damp the return of the inner tube to its initial position minimises the total shock to which the handlebars are exposed during the full range of operation of the arrangement.

Preferably, the damping means further comprises adjustment means for adjusting the pretension of the spring which damps downward movement of the handlebar support member and hence adjusting the shock damping. This arrangement allows the range over which the handlebars are allowed to travel to be adjusted in response to the type of shocks that are encountered by the cyclist. For example, the arrangement can be adjusted to damp high frequency/low amplitude road shocks or low frequency/high amplitude off-road shocks.

Embodiments of the invention will now be described, by way of example only, with references to the accompanying drawings in which: Figure 1 is a perspective view of a shock damping bicycle handlebar stem according to a preferred embodiment of the invention; Figure 2 is a perspective view of a shock damping bicycle handlebar stem according to a preferred embodiment of the invention mounted on a conventional bicycle; Figure 3 is a partially exploded perspective view of the shock damping bicycle handlebar stem shown in Figures 1 and 2; Figure 4 is a cross sectional view taken along line 3-3 of Figure 1, showing the internal details of the shock damping bicycle handlebar stem.

Figure 5 is a cross sectional view similar to that shown in figure 4 of a further embodiment of the invention.

With reference to figures 1 to 4 a shock damping bicycle handlebar stem 2 in accordance with the preferred embodiment of the invention comprises generally a fork ~post 4 that is conventionally affixed to the steering fork 5 (not shown in full) and a 15 handlebar clamp 6 for receiving the bicycle handlebars 8 (not shown in full). The damping means 10 is interposed between the fork post 4 and the handlebar clamp 6 and comprises an inner member 12 that is positioned telescopically inside an outer tube 14.

Both the inner member 12 and the outer tube 14 are closed at their upper ends and open at their lower ends. Unless otherwise indicated, it is preferred that the structural components of the shock damping bicycle handlebar stem be generally constructed of materials commonly used in conventional bicycle components for example, steel or ooo i steel alloys. It is also preferred that the outer tube 14 be square in cross section, although the outer tube might alternatively be, without limitation, rectangular, circular or elliptical in cross section.

The outer tube 14 is inclined to the fork post 4 at an angle in the range of 5 to degrees such that the lower end 16 of the outer tube 14 is forward of the upper end 18 of the outer tube 14. The angle at which the outer tube 14 is inclined up to the fork post 4 is preferred to be 15 degrees, although this angle may vary within the aforementioned range depending upon the particular construction of the bicycle frame and front fork assembly. The inner member 12 includes a connecting portion 20 which extends outwardly from the body thereof to the handlebar clamp 6, and the outer tube 14 includes a connecting portion 22 which extends outwardly from the body thereof to the fork post 4. The front face of the outer tube 14 has an elongated aperture 24 formed thereon and the inner member 12 is constructed such that at its front it extends through, but is constrained by, the elongated aperture 24. In operation the inner member 12 is constrained to slide in a linear path, without rotation, with respect to the outer tube 14 by virtue of the respective shapes of the inner member 12 and the outer tube 14.

Alternatively or additionally, in operation the inner member 12 may be constrained by the elongated aperture 24 to slide vertically in a linear path that coincides with the elongated aperture 24. The elongated aperture 24 may therefore act to guide the telescopic movement of the inner member 12 with respect to the outer tube 14 to ensure that the inner member 12 is correctly seated against, and aligned within, the outer tube 14 while sliding telescopically therein. Such an arrangement is intended to substantially reduce the amount of free play in any of the parts which extend between °9@ S* the fork post and the handlebars so as to preserve the precision and immediacy of the 15 command of the handlebars over the wheel, and minimise roll of the handlebars about 9*oo the longitudinal axis of the bicycle frame.

A bolt 26 comprising a threaded section on its upper and lower ends extends through a first hole 28 formed in the closed upper end 18 of the outer tube 14 and through a second hole 30 formed in the closed upper end 32 of the inner member 12 positioned telescopically therein. The bolt 26 also extends through an elastomeric element 34 that is positioned above the inner member 12 and between the closed upper 9.

end 18 of the outer tube 14 and a shoulder 36 on the bolt 26. A plate 40 is coaxially interposed on the bolt 26 between the elastomeric element 34 and the shoulder 36 on the bolt 26 so that the elastomeric element 34 can be retained above the closed upper end 32 of the inner member 12 without being compressed by the inner member 12 in its initial or rest position. Such an arrangement is preferred so that the elastomeric element is not degraded over time due to creep caused by compression of the elastomeric element by the inner member is in its static position. The plate 40 also acts as a bearing washer to prevent twisting of the elastomeric element upon adjustment of the spring force, as will be described below. A rubber washer 42 is also coaxially interposed between the shoulder 36 on the bolt 26 and the closed upper end 32 of the inner member 12. A spring 44 is placed around the portion of the bolt that extends beneath the closed upper end 32 of the inner member 12 and in its lower end 46 the bolt 26 threadedly engages a nut 48 formed integral on the bottom of a plate 50 so that the spring 44 is retained between the plate 50 and the closed upper end 32 of the inner member 12. An adjustment knob 52 is fixed to the portion of the bolt 26 that extends above the closed upper end 18 of the outer tube 14 such that by turning the adjustment knob 52 the nut 48 can be screwed back and forth on the threaded section on the lower end 46 of the bolt 26 in order to adjust the spring force (pretensioning). A lock nut 54 threadedly engages the threaded section on the upper end 56 of the bolt 26 below the adjustment knob 52 and retains a steel washer 58 and a rubber washer 60 respectively above the closed upper end 18 of the outer tube 14. Preferably a base 62 is removably inserted in the open lower end 64 of the outer tube 14 to support the structure thereof, and to prevent fouling of the damping mechanism and/or the loss of internal components in the event of a catastrophic failure.

15 In operation, downward force applied to the handlebars 8 relative to the fork post 4, as when the bicycle is subjected to a front wheel shock, forces the inner member 12 to slide telescopically downward in the outer tube 14 in a linear path that is inclined away from the fork post 4 and compresses the pretensioned spring 44 which absorbs a portion of the downward force imposed upon the arrangement to damp and slow the 20 downward movement of the handlebars 8 and thus significantly reduce the shock imparted to the upper body of the cyclist. The amount of shock damping provided by the preferred embodiment may be varied in response to the surface being overridden by turning the adjustment knob 52 to adjust the pretensioning of the spring 44. The inclination of the outer tube 14 of the damping means 10 in this embodiment confines 25 the range of movement of the handlebars 8 during shock damping within natural limits by specifically inhibiting any ergonomically undesirable rearward component of motion.

When the cyclist releases downward force on the handlebars 8, the compressed pretensioned spring 44 exerts a reactive upward force on the inner member 12 connected to the handlebar clamp 6 that urges the handlebars 8 upward to return to their initial position. The elastomeric element 34 acts as a damper to absorb a portion of the upward force imposed upon the arrangement by the return of the handlebars 8 to their initial position. The two rubber washers 42, 60 also serve to absorb a less substantial portion of the upward force imposed upon the arrangement by the return of the handlebars to their initial position. The inclusion of the elastomeric element, and to a lesser extent the washers 42, 60, minimises the total shock to which the handlebars 8 are exposed during the full range of operation of the arrangement.

The preferred embodiment of the invention will now be described with reference to figure 5. Like numerals indicate like features with respect to figures 1 to 4.

A bolt 26 comprising a threaded section on its upper and lower ends extends through a first hole 28 formed in the closed upper end 18 of the outer tube 14 and through a second hole 30 formed in the closed upper end 32 of the inner member 12 positioned telescopically therein. The bolt 26 also extends through an elastomeric element 34 and a spring 101 each of which are positioned above the inner member 12 and between the closed upper end 18 of the outer tube 14 and a shoulder 36 on an unthreaded section 38 of the bolt 26. The spring 101 is coiled around the outer surface of the elastomeric element 34. A spring 102 is coaxially interposed on the bolt 26 above the inner member 12 and below the shoulder 36. An elastomeric element (not shown) may be coaxially interposed on the bolt 26 above the inner member 12 and below the shoulder 36.

Where such an elastomeric element is included, the spring 102 is wound around its 20 outer surface. A progressive spring 44 and an elastomeric element 100 are each placed around the portion of the bolt that extends beneath the closed upper end 32 of the inner member 12 and in its lower end 46 the bolt 26 threadedly engages a nut 48 formed integral on the bottom of a plate 50 so that the spring 44 and the elastomeric element :100 are retained between the plate 50 and the closed upper end 32 of the inner member o o 25 12. The progressive spring 44 has greatest coil density (lowest pitch) nearest the upper end 32 of the inner member 12. An adjustment knob 52 is fixed to the portion of the bolt 26 that extends above the closed upper end 18 of the outer tube 14 such that by turning the adjustment knob 52 the nut 48 can be screwed back and forth on the threaded section on the lower end 46 of the bolt 26 in order to adjust the spring force (pretensioning). A lock nut 54 threadedly engages the threaded section on the upper end 56 of the bolt 26 below the adjustment knob 52 and retains a steel washer 58 and a rubber washer 60 respectively above the closed upper end 18 of the outer tube 14.

Preferably, the rubber washer 60 has a non-stick coating on its upper and lower faces to prevent it from sticking to either the steel washer 58 or the upper end 18 of the outer tube 14 and thereby preventing upward motion of the inner member 12 beyond the static or initial position. For example, said non-stick coating may be teflon. Preferably a base 62 is removably inserted in the open lower end 64 of the outer tube 14 to support the structure thereof, and to prevent fouling of the damping mechanism and/or the loss of internal components in the event of a catastrophic failure.

In operation, downward force applied to the handlebars 8 relative to the fork post 4, as when the bicycle is subjected to a front wheel shock, forces the inner member 12 to slide telescopically downward in the outer tube 14 in a linear path that is inclined away from the fork post 4 and compresses the pretensioned progressive spring 44 and elastomeric element 100 each of which absorb a portion of the downward force imposed upon the arrangement to damp and slow the downward movement of the handlebars 8 and thus significantly reduce the shock imparted to the upper body of the cyclist. The amount of shock damping provided by the preferred embodiment may be varied in response to the surface being overridden by turning the adjustment knob 52 to adjust the pretensioning of the spring 44. The inclination of the outer tube 14 of the damping means 10 in this preferred embodiment confines the range of movement of the o 20 handlebars 8 during shock damping within natural limits by specifically inhibiting any S" ergonomically undesirable rearward component of motion.

When the cyclist releases downward force on the handlebars 8, the compressed pretensioned spring 44 exerts a reactive upward force on the inner member 12 connected to the handlebar clamp 6 that urges the handlebars 8 upward to return to their 0• 25 initial position. The spring 102 (and, if included, the elastomeric element within the sping 102) prevent the upper end 32 of the inner member 12 from sharply impacting the shoulder 36 as the handlebars travel upwards. The elastomeric element 34 and the spring 101 act as a damper to absorb a portion of the upward force imposed upon the arrangement by the return of the handlebars 8 to their initial position. The two rubber washers 42, 60 also serve to absorb a less substantial portion of the upward force imposed upon the arrangement by the return of the handlebars to their initial position.

11 The inclusion of the elastomeric element 34 and the spring 101, and to a lesser extent the washers 42, 60, minimises the total shock to which the handlebars 8 are exposed during the full range of operation of the arrangement.

As the foregoing suggests, the described preferred embodiment of the invention provides a substantial reduction in shock imparted from bicycle to cyclist through the handlebars when compared to previously proposed pivoting linkage arrangements without unduly compromising the ergonomics or the lateral stability of the bicycle steering system.

The described arrangement has been advanced merely by way of explanation and many modifications may be made thereto without departing from the spirit and scope of the invention which includes every novel feature and combination of novel features herein disclosed.

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Claims

1. A shockdamping handlebar stem for a bicycle comprising damping means for resiliently interconnecting a fork post and a handlebar support member, said damping means being constructed and arranged to permit downward and upward movement of said handlebar support member relative to said fork post in response to shock encountered while the bicycle is in use such that downward movement of said handlebar support member is damped, said damping means further comprising an outer tube connected to the fork post or the handlebar support to 10 member and an inner member connected to the handlebar support member or the t to fork post, said inner member being coaxially mounted inside, and adapted to telescope with respect to, said outer tube while under pretension with respect to the outer tube by a first spring provided within the outer tube and wherein the downward movement of said handlebar support member occurs in a linear path ooo* inclined away from said fork post and upward movement of said handlebar support member occurs in a linear path inclined toward said fork post, said outer tube of said damping means being inclined to said fork post at an angle in the range of 5 to 20 degrees such that the lower end of said outer tube is forward of the upper end of said outer tube.

2. A shockdamping handlebar stem for a bicycle according to claim 1 wherein during the downward motion with respect to the outer tube of the inner member connected to the handlebar support member, the inner member slides telescopically in the outer tube and compresses the pretensioned first spring which absorbs a portion of the downward force imposed upon the arrangement to damp and slow the downward movement of handlebars supported by the handlebar support member such that when the cyclist releases downward force on the handlebars, the compressed pretensioned first spring exerts a reactive upward force on the inner member connected to the handlebar support member that urges the handlebars upward to return to their initial position. 13

3. A shockdamping handlebar stem for a bicycle according to any one of the preceding claims, said damping means further comprising a first elastomeric element to damp downward movement of said handlebarsupport member.

4. A shockdamping handlebar stem for a bicycle according to claim 3 wherein said first spring is coiled around the outer surface of, and mounted coaxially with respect to, said first elastomeric element. A shockdamping handlebar stem for a bicycle according to any one of the preceding claims wherein said first spring is wound such that the coil density per unit length of the spring decreases with distance from the top, or the bottom, of the spring.

6. A shockdamping handlebar stem for a bicycle according to any one of the preceding claims, said damping means further comprising a second elastomeric element to damp upward movement of said handlebar support member by compression of said second elastomeric element, said second elastomeric element 15 being arranged such that it is not compressed when said handlebar support *member is in a static position.

7. A shockdamping handlebar stem for a bicycle according to any one of the preceding claims, said damping means further comprising a second spring to damp upward movement of said handlebar support member by compression of 20 said second spring, said second spring being arranged such that it is not compressed when said handlebar support member is in a static position.

8. A shockdamping handlebar stem for a bicycle according to any one of claims 6 or 7 wherein said second spring is coiled around the outer surface of, and mounted coaxially with respect to, said second elastomeric element. 25 9. A shockdamping handlebar stem for a bicycle according to any one of the preceding claims wherein a rod is arranged to extend through the interior of the outer tube, said rod having a first retaining means located above the top of the said outer tube, said first retaining means preventing said rod from moving downwards with respect to said outer tube beyond a point defined by the said first retaining means by bearing against the top of the said outer tube, said rod passing through said inner member, said rod having a second retaining means mounted below the top of the inner member, said first spring being pretensioned by interposing said first spring between, and causing said first spring to be retained by, the top of the inner member and the said second retaining means. A shockdamping handlebar stem for a bicycle according to claim 9 wherein said rod includes a shoulder, said shoulder being located between the top of said inner member and the top of said outer tube such that said shoulder prevents the top of said inner member from moving upwardly with respect to said rod beyond said shoulder. 1.1. A shockdamping handlebar stem for a bicycle according to claim 10 wherein said second spring and/or said second elastomeric element is/are interposed between, and retained by, the said shoulder on the rod and the top of the outer tube, said second spring and/or second elastomeric element undergoing compression in the event that the upwardly moving inner member should transmit a force in its direction of motion to the said shoulder and thereby cause said rod to move upwards with respect to said outer tube.

12. A shockdamping handlebar stem for a bicycle according to claim 11 wherein a third spring and/or a third elastomeric element is/are interposed between, and retained by, the top of the inner member and the said shoulder on the rod. *ft.

13. A shockdamping handlebar stem for a bicycle according to any one of the preceding claims wherein said damping means further comprises adjustment means for adjusting the pretension of the first spring and hence adjusting the shock damping.

14. A shockdamping handlebar stem for a bicycle according to any one of claims 9 to 12wherein the height with respect to the said rod of the said second retaining 25 means is adjustable in order to adjust the pretension of the said first spring and hence adjusts the shock damping. A shockdamping handlebar stem for a bicycle according to claim 14 wherein the said rod passes through, and threadedly engages, said second retaining means such that the height with respect to the said rod of the said second retaining means is adjustable by means of rotation of said rod with respect to said second retaining means or rotation of said second retaining means with respect to said rod.

16. A shockdamping handlebar stem for a bicycle according to claim 15 wherein rotation of said rod with respect to said second retaining means may be effected by turning a lever means connected to said rod.

17. A shockdamping handlebar stem for a bicycle substantially as herein described with reference to figures 1, 2 ,3 and 4.

18. A shockdamping handlebar stem for a bicycle substantially as herein described with reference to figures 1, 2 ,3 and S Se *1