The present invention relates in general to an adjustable stem for a bicycle, specifically such that the location of a handlebar with respect to a cyclist can be adjusted.

As is known, a bicycle comprises a handlebar for steering the bicycle. Speaking generally, the handlebar has a substantially T-shaped configuration, having a leg to be mounted in a fork tube for connection with the front wheel of the bicycle, and having two arms extending sideways and carrying the handlebar grips. In the following, such arms extending sideways will be indicated as the actual handlebar, whereas the central leg which is intended for connection to the fork tube will be indicated as fork rod. The fork rod carries means for mounting the handlebar; the combination of the fork rod and such mounting means will be indicated as stem.

Conventionally, the position of the handlebar with respect to the fork tube is fixed. Nowadays, however, stems are adjustable, allowing the position of the handlebars to be adjusted in vertical direction and in horizontal direction.

Adjustable stems have been developed with different types of mechanism for effecting such adjustability. The present invention relates particularly to a mechanism comprising a coupling member, defining at its ends two horizontal pivot axes.

Adjustable stems for bicycles are already known. Figures 1A and 1B schematically illustrate one type of such adjustable stem, as disclosed by US-B1-6. 244.131. An adjustable stem 1 comprises a fork rod 10, which is shaped for insertion into a fork tube of a bicycle (not shown). At its lower end, the fork rod 10 is provided with a fork rod clamp member 11, for fixation of the fork rod within such fork tube. At its upper end, the fork rod is provided with a fork rod head 12, which comprises a fork rod head eye 13 displaced laterally with respect to the fork rod 10.

The adjustable stem 1 further comprises a handlebar clamp piece 20 associated with a handlebar 21. The handlebar clamp piece 20 comprises a coupling eye 22, displaced laterally with respect to said handlebar 21.

The adjustable stem 1 further comprises a coupling member 30 coupling the handlebar clamp piece 20 to the fork rod head 12 in an adjustable manner. More particularly, the coupling member 30 is coupled to the fork rod head eye 13 through a first pivot mechanism 41 defining a first pivot axis 31, and the coupling member 30 is coupled to the coupling eye 22 of the handlebar clamp piece 20 through a second pivot mechanism 42 defining a second pivot axis 32. The two pivot axes 31,32 extend substantially horizontally, perpendicularly to the lateral direction of the stem, and transverse to a lateral direction of a bicycle.

The coupling member 30 has a first coupling extremity 51 for coupling with the fork rod head 12. This first coupling extremity 51 has two arms 53L, 53R extending on opposite sides next to the fork rod head eye 13, and coupling with this eye, as will be explained in more detail. Further, the coupling member 30 has a second coupling extremity 52 for coupling with the handlebar clamp piece 20. This second coupling extremity 52 has two arms 54L, 54R extending on opposite sides next to the coupling eye 22 of the handlebar clamp piece 20, and coupling with this eye, as will be explained in more detail.

For fixation of the stem, said arms can be clamped together, clamping the eyes between them. It is possible that the coupling member 30 is a one-piece member, and that the arms can be elastically bent; however, in the embodiment illustrated in figure 1, the coupling member 30 comprises two individual coupling pieces 33L, 33R extending parallel to each other. The two opposite ends of a first or left coupling piece 33L constitute first and third arms 53L, 54L, respectively, while the two opposite ends of a second or right coupling piece 33R constitute second and fourth arms 53R, 54R, respectively.

For constituting the first pivot mechanism 41, the first arm 53L of the first coupling piece 33L is provided with a first pivot protrusion 34L fitting in a first pivot recess 35L

of the fork rod head eye 13. Similarly, the second arm 53R of the second coupling piece 33R is provided with a second pivot protrusion 34R fitting in a second pivot recess 35R of the fork rod head eye 13. The second pivot recess 35R and the first pivot recess 35L are arranged on opposite sides of the fork rod head eye 13, aligned with each other.

For constituting the second pivot mechanism 42, the third arm 54L of the first coupling piece 33L is provided with a third pivot protrusion 36L fitting in a third pivot recess 37L of the coupling eye 22 of the handlebar clamp piece 20, while the fourth arm 54R of the second coupling piece 33R is provided with a fourth pivot protrusion 36R fitting in a fourth pivot recess 37R of said coupling eye 22. The third pivot recess 37L and the fourth pivot recess 37R are arranged on opposite sides of said coupling eye 22, aligned with each other.

Alternatively, it is possible that the coupling pieces are provided with pivot recesses while the fork rod head and the handlebar clamp piece are provided with pivot protrusions.

The pivot protrusions and pivot recesses have a conical shape, so that, if the first pivot mechanism 41 is loose, the coupling member 30 can pivot with respect to the fork rod head 12, the first and second pivot protrusions 34L, 34R rotating within the first and second pivot recesses 35L, 35R, respectively, thus defining the first pivot axis 31.

Similarly, if the second pivot mechanism 42 is loose, the handlebar clamp piece 20 can pivot with respect to the coupling member 30, the third and fourth pivot recesses 37L, 37R rotating with respect to the third and fourth pivot protrusions 36L, 36R, respectively, thus defining the second pivot axis 32. For fixing the handlebar 21 securely in a chosen position with respect to the fork rod 10, the stem comprises clamping means for clamping the coupling pieces 33L, 33R firmly together, such that the above-mentioned rotations are inhibited. Such clamping means will be described later in more detail.

In the prior art mechanism, the conical pivot protrusions and pivot recesses are provided with teeth in the form of

radially extending ridges on the conical surface of such protrusions and recesses. When the coupling pieces are clamped together, the teeth of the protrusions will engage in the teeth of the corresponding recesses in order to effect a fixation. One disadvantage of such design is that the coupling member can only take a few discrete positions with respect to the fork head or the clamp piece. Another disadvantage is that the coupling pieces have to travel a relatively long way before the teeth are disengaged and the mechanism is loose.

In the prior art mechanism, the clamping means comprise screws, one screw for each pivot mechanism, these screws being tightened for clamping. This has the disadvantage that, in order to be able to adjust the position of the handlebar, one always needs to carry a tool. Further, loosening and fixing the pivot mechanism involves quite a lot of handling and takes relatively much time.

In the prior art stem, the width of the eye 13 (as measured along the first pivot axis 31) is smaller than the width of the fork rod head 12, such that the fork rod head 12 limits the rotation of the coupling member 30 with respect to the fork rod 10.

The present invention aims to solve these disadvantages.

In the preferred embodiment of the invention, all of said disadvantages are eliminated.

According to an important aspect of the present invention, the width of the fork rod head 12 is smaller than or equal to the width of the eye fork rod head 13, such that the coupling member 30 can rotate with respect to the eye 13 over a large angle, this angle being more than 300°. Then, it is also possible to mount the fork rod 10 with the eye 13 located backwards of the fork rod head 12, whereas in the state of the art it is only possible that the eye 13 is located in front of the fork rod head 12.

According to another important aspect of the present invention, the conical surfaces of the pivot protrusions and the corresponding pivot recesses are smooth, and the fixing

capability is based on friction. An important advantage is that the two pivot mechanisms can be adjusted to any angular position, in contrast to the state of the art design where only discrete positions are possible.

According to still another important aspect of the present invention, the clamping means comprise quick-release clamps. Although individual quick-release clamps for the two pivot mechanisms are possible, the two quick-release clamps are preferably integrated as one quick-release clamping device having one common clamp lever, so that both pivot mechanisms can be fixed or loosed by one single action, which improves the user-friendliness of the mechanism.

These and other aspects, features and advantages of the present invention will be further explained by the following description of preferred embodiments of the bicycle stem according to the present invention with reference to the drawings, in which same reference numerals indicate same or similar parts, and in which: figure 1 schematically shows a perspective view of a bicycle stem, illustrating general aspects thereof; figure 2 schematically shows a cross section of a bicycle stem, illustrating general aspects thereof; figure 3 schematically shows a detail out of the cross section of figure 2; figures 4A and 4B show a perspective view and a cross section, respectively, of an intermediate bush; figure 5A shows, in more detail, a cross section similar to figure 2, to illustrate a quick release clamp; figure 5B shows a side view of half of a coupling piece with a quick release clamp in a loosened condition; figure 5C shows a side view of half of a coupling piece with a quick release clamp in a clamped condition; figure 6A is a view comparable to figure 5A, schematically showing a quick release clamping device according to the present invention; figure 6B shows a view similar to figure 6A, of a portion of the quick release clamping device of figure 6A, in a loosened

condition; figure 6C shows a cross section of the quick release clamping device of figure 6A, in a clamped condition; figure 6D is a perspective view of a detail of the lifting mechanism of the quick release clamping device of figure 6A; figure 7 shows a perspective view of a bicycle stem with a dual clamping mechanism; figure 8 shows a perspective view of a bicycle stem with another embodiment of a dual clamping mechanism; figure 9 shows a perspective view of a dual lever; figures 10A-B illustrate an improved lever; figures 11A-D illustrate an embodiment of a stem with a mechanical transmission between the lever and the two clamping mechanisms; and figures 12A-C illustrate an embodiment of a stem with a hydraulical transmission between the lever and the two clamping mechanisms.

The present invention provides a bicycle stem of the type generally illustrated in figures 1-2, yet improved in several aspects.

A first aspect concerns the shape of the pivot protrusions and the pivot recesses. By way of example, figure 3 shows, on a larger scale than figure 2, a cross section of left coupling piece 33L including the first pivot protrusion 34L and also a cross section of the left half of an end part of fork rod head eye 13 including the first pivot recess 35L.

For sake of clarity, these parts are shown taken apart. The first pivot protrusion 34L has the shape of a truncated cone, with a conical surface 56 and an end surface 57. The first pivot recess 35L has a corresponding shape, with a conical side wall 58 and possibly a bottom wall 59. Preferably, however, the first pivot recess 35L meets the second pivot recess 35R, so that no bottom wall is present. The same applies for the other pivot protrusions and pivot recesses, but this is not illustrated.

In the design as shown in US-B1-6. 244.131, the pivot protrusions and the pivot recesses are provided with teeth on

their conical surfaces 56,57, hence the locking capability of the two pivot mechanisms is based on a locking of the engaging teeth. In contrast, according to the present invention, the conical surfaces 56 of the protrusions 34L, 34R, 36L, 36R preferably are smooth, i. e. such teeth are absent. Similarly, the conical side walls 57 of the recesses 35L, 35R, 37L, 37R preferably are smooth, i. e. without said teeth. An important advantage of this design is that both pivot mechanisms 41,42 can be adjusted continuously. Another important advantage of this design is that, starting from a fixed condition, a pivot protrusion only needs to be displaced over a relatively short distance with respect to the corresponding pivot recess, along the direction of the corresponding pivot axis, in order to loosen the connection enough to allow such pivot protrusion and pivot recess to rotate with respect to each other.

In this design proposed by the invention, the fixation capability is based on friction. An important design parameter in this respect is the top angle a of the pivot protrusions 34L, 34R, 36L, 36R (and the corresponding angle of the pivot recesses 35L, 35R, 37L, 37R). If top angle a is relatively small, the fixation capability is relatively high, but it is relatively difficult to loosen the mechanism; therefore, a preferably is larger than 15°. On the other hand, if a is relatively large, it is relatively easy to loosen the mechanism but the fixation capability is less good. In principle, a may be as large as 180°, such that friction surfaces 56 and 58 are flat, but the self-centering capability of a conical surface is preferred; therefore, a preferably is smaller than 170°. More preferably, the top angle a has a value in the range of 30-40°. An optimum value depends on the material used for the coupling pieces 33, the fork rod head 12, and the handlebar clamp piece 20. In an experimental setup, a top angle a of a approximately 36° has proven very satisfying.

Optionally, a conical intermediate bush 60 may be arranged between a pivot protrusion and the corresponding pivot recess. Such intermediate bush 60 is illustrated in the perspective view of figure 4A and the cross section of figure 4B. Preferably, and as shown, the intermediate bush 60 has a

gap 61 extending over the entire axial length of the bush, so that the size of the bush can adapt itself to the exact actual size of the pivot protrusion and the corresponding pivot recess while further the bush can disengage easily. As an alternative, the bush may be provided with a pattern of holes to give the bush the flexibility to adapt itself to the exact actual size of the pivot protrusion and the corresponding pivot recess and to promote easy disengaging.

The intermediate bush 60 may have a top angle substantially equal to a. However, in some cases it is to be preferred that the top angle of the intermediate bush is slightly larger or smaller than a, because such may promote easy disengaging of a pivot protrusion from its corresponding pivot recess.

Such bush 60 may be applied in cases where potential problems are expected, due to the materials of the pivot protrusion and the corresponding pivot recess tending to grate or wear or erode or the like. The material of the bush 60 may be chosen depending on the materials of the pivot protrusion and the corresponding pivot recess; suitable materials for the bush 60 are, for instance, anodized aluminum, steel, hard- pressed paper, plastic, or the like.

Usually, the pivot protrusion and the corresponding pivot recess will be made from aluminum. Then, it will be advantageous if the surface roughness of the bush 60 is chosen such that the projected area of the actual contact surfaces between the aluminum parts and the harder bush is such that, at maximum force of a clamping means, the aluminum is deformed elastically.

This roughness may for instance be achieved by spraying with grit or glass beads; then, the roughness obtained can be influenced by the choice of the size of the particles. The roughness may also be achieved by forming a suitable profile such as knurling or serrating; such formation processes are well suitable for controlling the obtained roughness to obtain a certain desired roughness. The roughness should not be made too high, because then grating tends to occur.

A particularly important aspect of the adjustable stem according to the present invention resides in the clamping mechanism. As mentioned before, in the state of the art adjustable stem, the clamping mechanism is implemented by a bolt or screw. The present invention proposes a quick release clamping mechanism 70 for each pivot mechanism 41,42, which will be explained in more detail by the following discussion with reference to figures 5A-C, which illustrate a possible embodiment of such clamping mechanism 70. Since the quick release clamping mechanism 70 can be identical for each pivot mechanism 41,42, same reference numerals in both pivot mechanisms 41,42 will be used. It is noted that, in figure 5A, the second pivot mechanism 42 is shown with an intermediate bush 60 as discussed above.

The quick release clamping mechanism 70 illustrated in figures 5A-C comprises a clamp rod 71 and a clamp lever 72 connected rotatably to one end of the clamp rod 71, which end will be indicated as the upper end of the clamp rod 71. The fork rod head eye 13 comprises a hole 73. The coupling pieces 33L, 33R are provided with through bores 74L, 74R, respectively, extending substantially coaxially with the first rotation axis 31 through the center of the pivot protrusions 34L, 34R, respectively. The clamp rod 71 extends through said bores 74L, 74R, extending substantially coaxially with the first rotation axis 31, i. e. transverse to a longitudinal direction of a bicycle. At its upper end, the clamp rod 71 is provided with a transverse pin 75. At its opposite or lower end, the clamp rod 71 is provided with screw thread 76, and a nut 77 is screwed on this screw thread 76, bearing against an outer side surface of the second coupling piece 33R. Screwing this nut 77 more or less on said screw thread 76 will adjust the clamping force of the clamping member 70, as will be clear to a person skilled in the art.

At each of the two ends of the transverse pen 75, a substantially circular lifting disk 81,82 is rotatably arranged eccentrically. A location at the circumference of such lifting disk 81,82 having the largest distance from the center of rotation is indicated as lifting point P. A clamp lever 72, extending substantially perpendicular with respect

to the rotational axis defined by the center line of the transverse pen 75, is fixed to both lifting disks 81,82. The direction of the clamp lever 72 is angularly displaced with respect to the location of the lifting point P, over an angle in the order of about 90°.

The lifting disks 81,82 bear against an outer surface of the first coupling piece 33L. Alternatively, it is of course possible that the lifting disks 81,82 bear against an outer surface of the second coupling piece 33R while the nut 77 bears against an outer surface of the first coupling piece 33L.

Figure 5B shows the clamp lever 72 in a loose position.

In this situation, the largest radius point P is rotated away from contact with the first coupling piece 33L, and the clamp is loose. Figure 5B shows the clamp lever 72 rotated clockwise, so that the lever 72 is substantially parallel to the first coupling piece 33L and the largest radius point P is closer to the first coupling piece 33L. In this situation, the lifting disks 81,82 tend to lift the transverse pin 75, so the lifting disks 81,82 and the nut 77 clamp the two coupling pieces 33L, 33R together. The combination of pin 75, lifting disks 81,82 and lever 72 will be indicates as lifting mechanism 80.

The amount of eccentricity of the lifting disks 81,82 with respect to the transverse pin 75 determines the distance that the transverse pin 75 can be lifted and therefore the distance that the two coupling pieces 33L, 33R can be moved apart in the loosened condition illustrated by figure 5B. In the prior art design, where the pivot protrusions and the pivot recesses are provided with teeth, this travel distance must be relatively large in order to allow such teeth to get out of engagement. More particularly, the travel distance should be at least equal to H/sin (a/2), wherein H is the height of the teeth. In contrast, because of the conical surfaces 56,58 of the pivot protrusions 34,36 and the pivot recesses 35,37 being smooth in the design according to the present invention, the travel distance may be much smaller.

This in turn implies that it is possible to have a clamping

member 70 in which the eccentricity of the lifting disks 81, 82 is relatively small, so that the clamping lever 72 can be handled with relatively little force.

In the adjustable stem 1, the coupling member 30 is provided with two pivot mechanisms 41,42 defining two pivot axes 31,32 ; therefore the stem needs two clamping mechanisms 70, one for each pivot mechanism 41,42. In a possible embodiment, such two clamping mechanisms can work independently from each other. In that case, while the two clamping mechanisms preferably are mutually identical, they may be mounted in opposite ways, so that the two clamping levers 72 are located on opposite sides of the coupling member 30. For instance, for clamping the first pivot mechanism 41, a clamp rod 71 may have its free end coupled to the second coupling piece 33R while the corresponding lifting mechanism 80 acts on the first coupling piece 33L. Then, in the clamped situation, the clamp lever will be located alongside the first coupling piece 33L. If the second clamping mechanism has its clamping rod 71 coupled to the first coupling piece 33L, its corresponding lifting mechanism 80 acts on the second coupling piece 33R and, in the clamped condition, the second clamping lever 72 would be located parallel to the second coupling piece 33R. In other words, both clamping levers 72 would be located on opposite sides of the coupling member 30. In the embodiment shown in figure 5A, however, both clamping levers 72 are located at the same side of the coupling member 30, next to each other.

As will be explained later in more detail, it is possible that both levers 72 are coupled to form one common lever, if pins 75 are aligned with each other.

Figures 5B-C show that the lever 72 preferably has an extension piece 72A making an angle with lever 72, the angle being in the order of about 90°. In the clamped position (figure 5C), extension piece 72A reaches over the coupling member 30, transverse to a longitudinal direction of a bicycle.

The present invention also provides an improved quick release device 170 for clamping together the two coupling pieces 33R and 33L. An important advantage of the quick release device 170 proposed by the present invention is that it comprises less parts and is easier to manufacture.

Importantly, the quick release device 170 according to the present invention does not comprise two parts connected rotatably to each other through a rotation axis.

Figures 6A-C illustrate the quick release device 170 according to the present invention. Again, a clamp rod 171 extends through bores in the pivot protrusions. The clamp rod 171 has a free end provided with screw thread 176, and is screwed into the first coupling piece 33L. The clamp rod 171 can be screwed in less or further in order to adjust the clamping force. A further securing nut (not shown) may be screwed on an extremity of the clamp rod 171 extending out of the first coupling piece 33L, in order to prevent rotation of the clamp rod 171. At its upper end, the clamp rod 171 is provided with a head 178 having a diameter larger than the clamp rod 171 itself.

Quick release clamping device 170 is provided with a lifting mechanism 180, comprising two lifting disks 181,182 located, parallel to each other, on opposite sides of the clamp rod 171, between the head 178 and the second coupling piece 33R. Each lifting disk 181,182 has a substantial circular contour over a large part of its perimeter,. and is provided with at least one cam 183,184. Each lifting disk 181,182 is seated in a corresponding recession 185,186 arranged at the surface of the second coupling piece 33R, having a contour corresponding to the circular contour of the lifting disks.

A clamp lever 172,172A is attached to both lifting disks 181,182. Particularly, the lever 172 has a lever body 187 and two lever arms 188,189 extending substantially parallel with respect to each other, at a mutual distance larger than the diameter of the head 178 of the clamp rod 171. Each arm 188, 189 is attached to one of said lifting disks 181,182, respectively. With respect to the rotational center of the lifting disks 181,182, the arms 188,189 extend in a

direction making an angle of approximately 90° with respect to the position of the cams 183,184.

If the lever 172 is moved to a position where the arms 188,189 extend substantially parallel to the clamp rod 171, the cams 183,184 are directed substantially perpendicular to the clamp rod 171: this is the loose condition. If the lever 172 is rotated, so that the lever comes to a position where the arms 188,189 extend substantially perpendicular to the clamp rod 171, the cams 183,184 are directed substantially parallel to the clamp rod 171, and lift the head 178 of the clamp rod 171: this is the clamped condition.

A head-supporting protrusion may be arranged on the side surface of the second coupling piece 33R, on both sides of the head 178 or the clamp rod 171, such as to support and guide the head 178 or the clamp rod 171 and to prevent a transverse movement of the clamp rod.

In the embodiment discussed, the cams 183,184 are contacting the head 178 in the clamped condition; alternatively, they may contact the corresponding coupling piece in the clamped condition.

In stead of only one cam, each lifting disk 181,182 may have two cams located opposite each other. Then, at the same shape of the cams, the lift distance as function of the lever rotation angle is increased.

Thus, the functioning of the lifting mechanism 180 is based on at least one lifting disk being located under the head of the clamping rod, this lifting disk lifting the clamping rod head on rotation of the lifting disk. In the drawings, an embodiment is shown where the lifting capabilities of a lifting disk are based on the contour of such disk. However, it is also possible that these lifting capabilities of a lifting disk are based on the contour of the under surface of the head or the upper surface of the coupling piece. For instance, the lifting disk may bear on a slightly tilted surface portion of the coupling piece; on rotation, the disk rolls over this surface portion and thus travels along this surface portion, being lifting thanks to the inclination of this surface portion. A similar approach is possible for the contour of the under surface of the clamping rod head.

In the above is described that the coupling member 30 may be provided with two independently operating clamping members 70,170. This means that, in order to loosen or clamp two pivot mechanisms 41,42, two individual clamp levers must be handled. The present invention provides a dual clamping device 200, which comprises two clamping members each clamping one of the two pivot mechanisms 41,42, and one common clamp lever.

Such design will have the advantage that only one action will suffice for clamping or loosening both clamping mechanisms 41, 42 simultaneously.

Although the dual clamping device 200 proposed by the present invention is particularly useful for application in a bicycle stem of the type discussed, such dual clamping device 200 is applicable in any mechanism having two pivot axes extending parallel, where fixation is based on a clamping mechanism exerting a clamp force parallel to the pivot axes.

The dual clamping device 200 proposed by the present invention is illustrated schematically in the perspective views of figures 7 and 8. Figure 7 shows an embodiment based on the clamping member 70 of figures 5A-C, while figure 8 is a similar view showing an embodiment based on the clamping member 170 of figures 6A-D. It is noted that, in figure 7, the dual clamping device 200 is mounted on a stem of the type illustrated in figure 1, having a fork rod 10 and an eye 13 part of a fork rod head 12. On the other hand, in figure 8, the dual clamping device 200 is mounted on a clamp 14 carrying the fork rod head 12 with the eye 13, this clamp 14 being design for attachment on the upper end of a fork rod.

In both cases, the dual clamping device 200 comprises two clamping rods 71 or 171, mounted parallel to each other, having their respective lifting mechanisms 80,180 located at the same side of the coupling member 30.

In the case of figure 7, the two clamping rods 71 have their respective transverse pins 75 aligned with each other.

Each clamping rod 71 is provided with its associated lifting mechanism 80 as described above. These details of the two clamping rods 71 are not illustrated in great detail in figure 7.

In the case of figure 8, the rotation orientation of the two clamping rods 171 is not important, as the two heads 178 can have a substantially flat lower surface. Each clamping rod 171 is provided with its associated lifting mechanism 180 as described above. The two pairs of seats 185 for the lifting disks 181,182 are aligned with each other, so that the rotation axes of the two pairs of lifting disks 181,182 are aligned with each other. These details of the two clamping rods 171 are not illustrated in great detail in figure 8.

Each lifting mechanism 80; 180 associated with each clamping rod 71; 172 comprises a clamp lever 72; 172, each clamp lever 72; 172 being of the type as described above, comprising a lever body 87; 187 and two arms 88,89 ; 188,189 connected to corresponding lifting disks 81,82 ; 181,182.

Each clamping lever body 87; 187 has a substantially L- shaped cross section, having a short leg and a large leg, the short leg carrying the arms with the disks. Then, in the clamped position, the two short legs of the two levers are substantially parallel to the side surface of the coupling pieces, whereas the two long legs of the levers lie over the coupling member 30, substantially parallel to the two pivot axes.

The above description still allows for two independent clamp levers 72; 172, which is an option falling under the inventive idea. However, in the dual clamping device 200 preferred by the present invention, the two clamping levers are shaped as one integral dual lever 190 having a substantially L-shaped cross section, as clearly illustrated in figures 7 and 8. This one single lever 190 has one common short leg 191 connected to two sets of lifting disks 81,82 ; 181,182, and one common long leg 192 lying over the coupling member 30. Alternatively, it is possible that the one integral lever 190 has separate short legs which meet at one common long leg.

Figure 9 schematically shows a perspective view of such dual lever 190. A big advantage of this dual lever 190 is, on the one hand, the fact that it is one piece. Importantly, the dual lever 190 including the two sets of lifting disks 81,82 ;

181,182 can easily be manufactured, for instance by injection molding. In that case, after cutting the injection-molded work piece to size, only the gaps between two lifting disks 81,82 ; 181,182 and the corresponding arms 88,89 ; 188,189 need to be cut away for allowing room for the corresponding clamping rods.

Figure 10 illustrates a further improvement of a lever, in this case the dual lever 190 of figure 9. If a clamping mechanism is in the clamped position, a clamping lever itself is clamped, and it may take some force to get hold of the lever end and rotate the lever. This is especially the case where the length of such lever is relatively small. In the case of a bicycle, it is, of course, not intended that tools are used for forcing the lever open, if only because such might damage the mechanism. Without tools, however, it may be very difficult for a user to actuate the lever, especially if the user has relatively long nails.

The further improvement illustrated in figure 10 aims to solve this problem. At the free end of the lever, in this case the free end of the long leg portion 192 of single lever 190, an extension piece 300 is mounted pivotably. Normally, during use in the clamped position, the long leg portion 192 of single lever 190 lies over the coupling member 30, while the extension piece 300 is directed downwards along the side of coupling member 30 (not shown in figure 10). In this orientation, illustrated in figure 10A, extension piece 300 may also help to prevent dirt entering the mechanism, and it may benefit the esthetic look of the coupling member.

Although there may be some friction between the long leg portion 192 of single lever 190 and its extension piece 300 in order to prevent rattling, the extension piece 300 in principle is free from any load. If it is desired to loosen the clamping mechanism, the user first will rotate the extension piece 300 to a horizontal orientation, i. e. an orientation in line with the long leg portion 192 of single lever 190, as illustrated in figure 10B. This rotation will be practically without effort. In this horizontal orientation, the extension piece 300 will meet a stop defined by the long

leg portion 192 of single lever 190, so that a further rotation of the extension piece 300 with respect to lever 190 is no longer possible. In this orientation, a force exerted by the user on the extension piece 300 will be transmitted to the lever 190.

In this orientation, the rotated extension piece 300 will offer a good grip for the user so that the user is able to exert a force, while further the increased length of the lever results in a lower force requirement for rotating the lever.

Said stop may be implemented in many ways. In the embodiment shown, the extension piece 300 has a body 301 and two arms 302,302 mounted pivotably on opposite sides of the long leg portion 192 of single lever 190, the rotation axis of this pivot construction being located at some distance from the extreme end of lever 190, this distance being larger than the length of said arms 302,303. Then, in the substantial horizontal orientation, the extension piece body 301 abuts the end portion of lever 190.

In the embodiment described above and illustrated in figures 10A-B, the clamp bolts are directed substantially horizontally, transverse to the longitudinal direction of the stem, and the lever 190 has a pivotable connection with the clamp bolts at one lateral side of the coupling member 30, the lever 190 having a short leg 172 extending, in the clamped condition, substantially vertically and having a long leg 172A extending in the clamped condition, substantially horizontally over the coupling member 30 towards the other lateral side of the coupling member 30, while the pivot between pivotable extension piece 300 and lever 190 is located at said other lateral side of the coupling member 30. The long leg 172A is fixedly connected to the short leg 172. As an alternative, it is possible that the long leg 172A is pivotably connected to the short leg 172 and, as such, fulfills the functions as described above with reference to extension piece 300. Then, the pivotable long leg 172A and the extension piece 300 may be implemented as an integrated whole, or the extension piece 300 may be pivotably connected to long leg 172A, or the extension piece 300 may be omitted.

Thus, the present invention succeeds in providing a quick release handlebar stem with two pivots, each pivot being clampable by an associated clamping mechanism, both clamping mechanisms being actuated by one common lever. In the above, examples have been discussed of embodiments where the lever is acting mechanically and directly on the clamping mechanisms.

In the following, alternative embodiments will be discussed where a leverage construction is present between the lever and the two clamping mechanisms. Figures 11A-D illustrate an embodiment where this leverage construction is a mechanical construction, and figures 12A-C illustrate an embodiment where this leverage construction is a hydraulical construction.

Figure 11A is a view similar to figure 5A of a dual quick release clamping device 400, comprising two clamping mechanisms 41,42, each comprising a clamping rod 71, attached in this case to the righthand coupling piece 33R through a nut 77. At is upper end, each clamping rod 71 has a head 78. The dual quick release clamping device 400 comprises lifting means 401 for exerting a lifting force on the heads 78 of the clamping rods 71.

Between each head 78 and the lefthand coupling piece 33L, an associated lifting lever 410 is arranged. Since both lifting levers may be identical, only one lifting lever will be described in more detail.

The lifting lever 410 has a hole or bore 411 through which the clamping rod 71 extends. The lifting lever 410 has a lifting lever arm 420 extending substantially perpendicular to the clamping rod 71, directed towards a central location of the coupling member 30, i. e. the lifting lever arms 420 of both lifting levers 410 are directed towards each other. At its free end, the lifting lever arm 420 is provided with an arm head 421, which preferably has, at least partly, a ball shape.

Opposite the lifting lever arm 420, the lifting lever 410 is pivotably supported on the lefthand coupling piece 33L, preferably such that a pivot axis 435 extends substantially perpendicular to the lifting lever arm 420, as illustrated in the side view of figure 11B. In the illustrated embodiment, a pivot support 430 is defined by two pivot balls 431,432

arranged on the lefthand coupling piece 33L, each pivot ball 431,432 being received in a corresponding pivot bowl 433,434 arranged in the lifting lever 410. The mutual location of the pivot balls 431,432 defines the location of the pivot axis 435. The engagement of the pivot balls 431,432 in the pivot bowls 433,434 will prevent a rotation of the lifting lever 410 with respect to the clamping rod 71.

The pivot balls and pivot bowls may have a semi-spherical shape, or a semi-cylindrical shape, wherein the central axis of such cylindrical shape will be aligned with the pivot axis 435. Alternatively, instead of two ball/bowl combinations, the pivot support 430 may be defined by one, preferably relatively long, semi-cylindrical pivot ball received in one semi- cylindrical pivot bowl. Also, as an alternative, the convex balls may be arranged on the lifting lever 410 while the concave bowls are arranged in the lefthand coupling piece 33L.

A lever 472,472A comprises an actuation cylinder 480, in which an eccentric bore 481 is arranged. As clearly visible in figures 11A and 11B, both arm heads 421 of both lifting levers 410 are received in said bore 481 of said actuation cylinder 480. Rotation of the lever 472,472A will cause a rotation of the actuation cylinder 480 with respect to the arm heads 421 of both lifting levers 410. Further, the outer surface of the actuation cylinder 480 is supported against the side surface of the lefthand coupling piece 33L.

Figure 11C is a side view comparable to figure 5B, while figure 11D is a side view comparable to figure 5C. Figures 11A and 11C show the dual quick release clamping device 400 in the loosened condition, where the lever 472,472A is rotated such that the wall thickness of the actuation cylinder 480 located between the arm heads 421 and the lefthand coupling piece 33L is relatively small.

Figure 11D shows the dual quick release clamping device 400 in the clamped condition, where the lever 472,472A is rotated over 180° such that the wall thickness of the actuation cylinder 480 located between the arm heads 421 and the lefthand coupling piece 33L is relatively large, and the arm heads 421 are lifted with respect to the side surface of the lefthand coupling piece 33L. Now, the actuation cylinder

480 exerts a lifting force on the arm heads 421, while the lifting levers 410 exert a clamping force on their corresponding clamping rods 71. As clearly visible in figures 11A and 11B, the distance from arm head 421 to clamping rod 71 is larger than the distance from pivot axis 435 to clamping rod 71, so that the clamping force on the clamping rods 71 is larger than the lifting force exerted by the actuation cylinder 480 by a factor corresponding to the ratio of said two distances, as will be clear to a person skilled in the art. Preferably, this ratio is within the range of 5-10.

The dual quick release clamping device 400 offers several advantages. It is possible to achieve a larger clamping force with reduced lifting force. Reducing the lifting force will accordingly reduce the amount of friction experienced by the lever, and will also reduce the force which the user must exert. Further, the mechanism may show increased elastic deformation, such as by bending of the lifting levers 410, which is favorable, because it provides increased pre-tension in the mechanism which will reduce the risk of unintentionally loosening the mechanism. Further, the mechanism is capable of equally distributing the clamping force over both clamping mechanisms 41,42.

Figure 12A is a view similar to figure 11A of a dual quick release clamping device 500, comprising two clamping mechanisms 41,42, each comprising a clamping rod 71, attached in this case to the righthand coupling piece 33R through a nut 77. At is upper end, each clamping rod 71 has a head 578 implemented as a piston head, sealingly received in a corresponding piston chamber 510 arranged in the lefthand coupling piece 33L. The dual quick release clamping device 500 comprises lifting means 501 for exerting a lifting force on the piston heads 578 of the clamping rods 71.

In a manner known per se, a first sealing member 579 assures a fluid tight contact between a circumferential outer surface of the piston head 578 and a wall of the piston chamber 510, while a second sealing member 577 assures a fluid tight contact between the clamping rod 71 and the lefthand coupling piece 33L.

In the lefthand coupling piece 33L, an actuation piston 525 is sealingly arranged in an actuation piston chamber 520, which communicates to both of said piston chambers 510 via corresponding communication channels 521, preferably ending in the bottom of said piston chambers 510, as shown. The actuation piston chamber 520 and the piston chambers 510 are filled with a transmission fluid.

A lever 572,572A comprises two arms 561,562, connected to each other by an axle 563, which is rotatably supported by two axle supports 564,565 of the lefthand coupling piece 33L.

An actuation disk 550 is mounted eccentrically on axle 563, at a location between said two axle supports 564,565, contacting said actuation piston 525.

Figure 12B is a side view comparable to figure 11C, while figure 12C is a side view comparable to figure 11D, the figures 12B-C showing the dual quick release clamping device 500 partly in cross section. Figures 12A and 12B show the dual quick release clamping device 500 in the loosened condition, where the lever 572,572A is rotated such that the disk radius of the portion of the actuation disk 550 located between the axle 563 and the actuation piston 525 is relatively small.

Figure 12C shows the dual quick release clamping device 500 in the clamped condition, where the lever 572,572A is rotated over 180° such that the disk radius of the portion of the actuation disk 550 located between the axle 563 and the actuation piston 525 is relatively large, and the actuation piston 525 is pressed into the actuation piston chamber 520.

Transmission fluid is pressed from the actuation piston chamber 520 into the piston chambers 510, exerting a lifting force on the piston heads 578 of the clamping rods 71. As clearly visible in figure 12A, the surface area of the piston heads 578 of the clamping rods 71 is larger than the surface area of the actuation piston 525, so that the clamping force on the clamping rods 71 is larger than the lifting force exerted by the actuation disk 550 by a factor corresponding to the ratio of said two areas, as will be clear to a person skilled in the art. Preferably, this ratio is within the range of 5-10.

The dual quick release clamping device 500 offers several advantages comparable to the advantages described above in relation to the device 400. A further advantage is that the actual length of the section of the clamping rod 71 projecting into the piston chamber 510 is not critical, since the amount of fluid in the piston chambers will compensate this. In fact, if adjustment of the clamping device 500 by tightening or loosening the nuts 77 is desired, it suffices to adjust only one nut.

Although the present invention has been explained in the foregoing by description of some preferred embodiments, it should be clear to a person skilled in the art that the present invention is not limited to such embodiments; rather, various variations and modifications are possible within the protective scope of the invention as defined in the appending claims.

For instance, with respect to the quick release clamping mechanism 400 illustrated in figures 11A-D, although a common actuation cylinder 480 is preferred, it is within the scope of this invention that both arm heads 421 are received in individual actuation cylinders which are individually rotated by individual levers or rotated in common by one common lever.

Further, with respect to the quick release clamping mechanism 500 illustrated in figures 12A-C, although a common actuation piston 525 is preferred, it is within the scope of this invention that both piston heads 578 are actuated by individual actuation pistons which are individually pressed by individual actuation disks which are individually rotated by individual levers or rotated in common by one common lever.

The invention is particularly useful in a stem where the handlebar clamp piece 20 is implemented as a handlebar house housing two inner ends of two handlebar halves 21 which are pivotably received in said house, as illustrated in figure 7.

Such design is described more extensively in international patent application PCT/NL98/00658.