ADJUSTABLE HANDLEBAR SHAFT

Abstract: An adjustable handlebar shaft for interconnecting a handlebar (6) and a member to be steered comprises a rod (1) and a front assembly (5) which extends at a variable angle ( alpha ) to the rod (1). The front assembly (5) is provided with means (56) for fastening the handlebar (6) at one end. Either the rod (1) or the front assembly (5) comprises a cup (7), while the other of the two comprises a cylindrical roller (58) held therein, the cup (7) forming part of a clamping member (9, 92) which encloses the roller (58) substantially entirely. An optimum clamping force is obtained thereby between the two parts (7, 58).

Description: Adjustable handlebar shaft The invention relates to a handlebar shaft for the interconnection of a handlebar and a member to be steered, which shaft comprises a rod and a front assembly which extends at an angle to the rod and is provided with means for fastening the handlebar, said rod and front assembly comprising a cup in the one part in which the other part is clamped in with an at least substantially coaxially curved surface. Such an adjustable handlebar shaft offers the possibility of adjusting the position of the handlebar to the specific and individual requirements of the rider, especially on a bicycle, scooter, moped or motorbike, so as to achieve an ergonomic sitting attitude. Existing adjustable handlebar shafts may be subdivided into two types, i.e. on the one hand handlebar shafts which are steplessly adjustable and on the other hand those which are adjustable not continuously, but in discrete steps. In the latter type of handlebar shafts, the rod and the front assembly are usually interconnected by an interposed tooth arrangement. Apart from the fact that the handlebar shaft is thus not continuously adjustable, and therefore not exactly adaptable to the specific wishes of the rider, these shafts have the further disadvantage that they are comparatively prone to wear and can work themselves loose owing to vibrations which act thereon in practice in the long run, which in an extreme case may result in broken teeth. Preferably, therefore, a steplessly adjustable handlebar shaft is used in which such teeth are absent. Such a steplessly adjustable handlebar shaft is known, for example, from a Netherlands Patent Application laid open to public inspection under no. 9100168. In the handlebar shaft described therein, the front assembly rests with a curved surface in a cup present at the end of the rod. The front assembly here is fastened to the rod by means of a bolt which passes through a slot in the front assembly, which slot facilitates a rotation of the assembly through a certain angle in the cup. The front assembly can be secured in the rod by means of the bolt through the interposition of a pressure roller which presses the front assembly securely into the cup. Although this achieves a continuous adjustability of the handlebar shaft and the construction in itself is not prone to wear, it is found in practice that the construction is not capable of withstanding extreme conditions in heavy terrain or the force exerted by a powerful cyclist. It is not unthinkable that the mutual locking of the two parts of the handlebar shaft will be insufficient for coping with conditions of this type. The present invention has for its object to provide an adjustable handlebar shaft of the kind mentioned in the opening paragraph whose constituent parts have an improved mutual fixation possibility. To achieve this object, a handlebar shaft of the kind mentioned in the opening paragraph is characterized in that the curved surface forms part of a cylindrical roller which extends between two mutually separated legs, and in that the cup forms part of a clamping member which encloses the roller at least substantially completely. It is achieved thereby that the clamping surface between the two parts of the handlebar shaft extends over substantially the entire surface area of the roller instead of over only part thereof, as is the case in the known handlebar shaft. A considerably greater clamping force can thus be exerted than with the known handlebar shaft, which greater clamping force has proved capable in practice of keeping the two parts satisfactorily fixed in the desired ergonomic position even under the most adverse conditions. A special embodiment of the handlebar shaft according to the invention is characterized in that the rod comprises the clamping member with the cup at one end, and in that the front assembly comprises two legs of a U-shaped endpiece, which legs enclose the cylindrical roller. An important advantage of such a construction is that the front assembly here is capable in principle of a rotation through an angle of practically 360 degrees and in particular is not restricted by a length of a slotted hole to be provided therein, as in the known handlebar shaft. The clamping member will often comprise screwing means for exerting the required clamping force. These screwing means may be provided separately. A preferred embodiment of the handlebar shaft according to the invention, however, is characterized in that the rod is provided with an expander bolt with an expander plug for clamping the handlebar shaft in the member to be steered, and in that the clamping member is clamped around the cylindrical roller by means of said expander bolt. Screwing means already present are used in this case for securing the clamping member. It is thus possible to set the handlebar to the desired height and the desired orientation by a single operation of the expander bolt. A special embodiment of the handlebar shaft according to the invention is for this purpose characterized in that the clamping member comprises a detachable bracket which encloses the cylindrical roller and is fastened at a first side adjacent a first edge of the cup and is provided with a bore for receiving the expander bolt at an opposite side. To mount the handlebar shaft, the front assembly is laid with its cylindrical roller in the cup in this case, and the bracket is fastened to the first side near the edge of the cup and laid around the roller. Then the expander bolt is inserted into the rod through the bore in the bracket and tightened. In a preferred embodiment, the bracket is fastened with hinging possibility near the edge of the cup. A further special embodiment of the handlebar shaft according to the invention is characterized in that the front assembly has a variable length which is adjustable by means of at least two telescopic parts. The distance from the handlebar shaft to the rider can also be adjusted in this case, which further improves the ergonomic quality of the assembly. This is of particular importance for a further embodiment of the handlebar shaft according to the invention, which is characterized in that the cylindrical roller forms part of a continuous bar which extends on either side of the front assembly and is fitted with arm rests. Thanks to the telescopic adjustability of the length of the front assembly, the position of the handlebar shaft can now be exactly attuned relative to the arm rests, so that an optimum steering position can be created. The invention will now be explained in more detail with reference to a number of embodiments and an accompanying drawing, in which: Fig. 1A is a cross-section of a first embodiment of a handlebar shaft according to the invention, Fig. IB is a rear view of the handlebar shaft of Fig. 1 A, Fig. 2 is a cross-section of the handlebar shaft of Fig. 1 drawn in two different positions, Fig. 3 is a cross-section of a rod of a second embodiment of a handlebar shaft according to the invention, Fig. 4 is a cross-section of the second embodiment of the handlebar shaft according to the invention with the rod of Fig. 3, Fig. 5 is a cross-section of a third embodiment of a handlebar shaft according to the invention during the process of mounting the front assembly thereof, and Fig. 6 is a perspective view of a fourth embodiment of a handlebar shaft according to the invention. The drawings are purely diagrammatic and not drawn to scale. Some dimensions are particularly exaggerated for the sake of clarity. Corresponding parts have been given the same reference numerals as much as possible in the Figures. The handlebar shaft of Fig. 1 comprises a hollow rod 1 in whose lower side a notch 2 is provided for accommodating an expander plug 3. The expander plug 3 has a continuous internal screwthread into which an expander bolt can be inserted at the upper side through a bore 4 for clamping the rod 1 in a member to be steered, such as the fork of a bicycle, moped, motorbike or scooter, etc. A front assembly 5 is provided at an angle to the rod 1, in this case consisting of two coaxial telescopic parts 51,52 which can slide one inside the other in inward and outward direction and can be fixed relative to one another at the desired length by clamping means 53. Means 54 for fastening a handlebar 6 are present at an end of the front assembly 5. The handlebar 6 is inserted into the round opening 55 and clamped tightly therein by means of jaws 56 and a bolt arranged in these jaws. Either the rod 1 or the front assembly 5 comprises a cup 7 in which a curved surface 8 of the other part of the two is held, with the object of enabling the adjustment of the handlebar shaft to the requirements of a user/rider not only as regards its length but also as regards its orientation. In the present embodiment, the cup 7 is formed at the end of the rod 1 in a clamping member 9. The curved surface 8 forms part of a cylindrical roller which is enclosed between two legs of a U- shaped endpiece 57 of the front assembly, which legs extend towards the rod. In the undamped state, the roller can rotate freely in the cup 7 of the clamping member 9, and the front assembly may be set in the desired position. To fix the front assembly in this position, the clamping member 9 is tightened by means of a bolt in the jaws 91 and thus clamped around the cylinder 58. Such a fixation is found to be capable of withstanding the most severe conditions. Thus both the length of the front assembly and its angle to the rod are variable in the handlebar shaft of the present embodiment, and accordingly exactly adjustable to the build and desired attitude of the rider. This is depicted more clearly in Fig. 2, which shows two positions, the arrow i indicating the length adjustment and the arrow α the angle adjustment of the front assembly 5. In the preceding embodiment, the cylindrical roller 58 was clamped in by means of additional screwing means in the jaws 91 of the clamping member. It is alternatively possible, however, for the fixation of the front assembly to make use of the expander bolt 10 already present in the rod 1. A second embodiment of the clamping member 9 comprises for this purpose a detachable bracket 92 which closes around the cylindrical roller 58, see Figs. 3 and 4. The bracket is fastened adjacent the edge of the cup 7 by means of a threaded member, in this example a socket screw, after the front assembly 5 has been laid with the cylindrical roller 58 in the cup 7. At the opposite side, the bracket 92 comprises a bore 12 which is to receive the expander bolt 10, so that the bracket 92 can be clamped around the cylindrical roller 58 in that the expander bolt 10 is tightened. Both the height and the position of the handlebar 6 may thus be adjusted by means of the expander bolt 10 in a single operation. To simplify the mounting of the handlebar further, a third embodiment of the handlebar shaft according to the invention, see Fig. 5, comprises a clamping member 9 with a detachable bracket 92 which is fastened near the edge of the cup 7 with hinging possibility about a pin 93. If so desired, several hinges 94 may be included in the bracket 92 to facilitate mounting thereof further. A fourth embodiment of the handlebar shaft according to the invention is shown in Fig. 6. Here the cylindrical roller 8 forms part of a continuous bar 14 which extends on either side of the front assembly 5. The bar 14 is provided with arm rests on either side of the front assembly 5 with the object of further enhancing rider comfort. The arm rests are fastened to the bar 14 by means of clamping bands. The distance from the arm rests 15 to the handlebar shaft 6 can be adjusted as desired thanks to the telescopic parts 51,52 of the front assembly. Although the invention was described in detail with reference to only a few embodiments, it will be clear that the invention is by no means limited to the examples given. Many more variations are indeed possible to those skilled in the art within the scope of the invention. Thus, for example, the cup may be provided in the front assembly and the cylindrical roller may form part of the rod. Any suitable construction may be used in principle for the front assembly such as, for example, a round, oval, or differently shaped tube construction, possibly resilient owing to the use of an elastomer material, a helical spring, or hydraulic means. For placing a front assembly having a dimension different from that of the cylindrical roller, it is possible to provide shells or insert bushes in the cup to compensate for the dimensional difference. Such a shell or insert bush may then be pressed against the cylindrical roller by means of a bolt applied thereto, if so desired, in order to increase the clamping force. Furthermore, grooves, knurls, or other profiles may be provided in the wall of the cup or of the cylindrical roller to enhance the mutual clamping force further. In general, the present invention offers an adjustable handlebar shaft with a high degree of reliability which is maintained also over a long period of time and under extreme conditions.

Claims: CLAIMS 1. A handlebar shaft for the interconnection of a handlebar and a member to be steered, which shaft comprises a rod and a front assembly which extends at an angle to the rod and is provided with means for fastening the handlebar, said rod and front assembly comprising a cup in the one part in which the other part is clamped in with an at least substantially coaxially curved surface, characterized in that the curved surface forms part of a cylindrical roller which extends between two mutually separated legs, and in that the cup forms part of a clamping member which encloses the roller at least substantially completely. 2. A handlebar shaft as claimed in Claim 1, characterized in that the rod comprises the clamping member with the cup at one end, and in that the front assembly comprises two legs of a U-shaped endpiece, which legs enclose the cylindrical roller. 3. A handlebar shaft as claimed in Claim 2, characterized in that the rod is provided with an expander bolt with an expander plug for clamping the handlebar shaft in the member to be steered, and in that the clamping member is clamped around the cylindrical roller by means of said expander bolt. 4.A handlebar shaft as claimed in Claim 3, characterized in that the clamping member comprises a detachable bracket which encloses the cylindrical roller and is fastened at a first side adjacent a first edge of the cup and is provided with a bore for receiving the expander bolt at an opposite side. 5. A handlebar shaft as claimed in Claim 4, characterized in that the bracket is fastened with hinging possibility near the edge of the cup. 6. A handlebar shaft as claimed in any one of the preceding Claims, characterized in that the front assembly has a variable length which is adjustable by means of at least two telescopic parts. 7. A handlebar shaft as claimed in Claim 6, characterized in that the cylindrical roller forms part of a continuous bar which extends on either side of the front assembly and is fitted with arm rests.

Inventors: VAN BEEK MAAS, VAN BEEK, MAAS
Applicants: BEEK MAAS VAN, VAN BEEK, MAAS
Application year: 1995
Main classification: B62K21
IPC codes: B62K21