Title of Invention

''BICYCLE FRAME''

Abstract

The invention relates to a bicycle frame. It comprises of a main tube assembly with an oval cross-section and having a tuning for like configuration, the end of each tine member of said tube assembly being provided with a drop-out for mounting the rear wheel assembly and the other end thereof being provided with a head tube for mounting the front wheel assembly. A substantially vertical seat tube is fixed centrally at the U-turn of said main tube assembly and the bottom end of said seat tube is provided with a bracket for mounting the chain wheel. A crank assembly provided with a clamp for mounting the saddle is provided at the top end. A pair of support tubes are provided, one connecting the top end and the other connecting the bottom end of said seat tube with the stem of said main tube assembly. A pair of seat stay tubes are provided connecting the top end of said seat tube with the two line members of said main tube assembly.

Full Text

This invention relates to improvements in or relating to bicycle frames. The existing bicycle frames are made of circular section tubes of varying diameters and thicknesses with brazed or welded joints. Generally, all bicycle frames for adult usage have a diamond configuration for the front and a triangular configuration for the rear. These known bicycle frames have many inherent drawbacks. For instance, the chain cannot be easily removed without delinking, because of the rear triangular configuration of the frame. Due to this problem, chain removal is laborious and time consuming, and moreover skilled persons are required for servicing and maintenance jobs. Further, due to the front diamond configuration of the frame, the brake cable routing for the rear brake undergoes two bending, and this causes more friction for movement of the cable, thereby reducing the braking efficiency and necessitating more force to be applied on the brake lever. Furthermore, as the top tube is connecting the top ends of the head tube and the seat tube, the height of the top tube from the ground is more and, therefore, it is often felt inconvenient, especially for ladies, in regular use. An object of the present invention is to avoid or at least minimise the abovementioned drawbacks. Another object of the present invention is to provide a better aesthetic appearance and to impart more rigidity to the cycle frame on vertical loading. With these and other objects in view, the present invention provides a bicycle frame, comprising a main tube assembly with an oval cross-section and having a tuning fork like configuration, the end--of each tine member of said tube assembly being provided with a drop-out for mounting the rear wheel assembly and the other end thereof being provided with a head tube for mounting the front wheel assembly, a substantially vertical seat tube fixed centrally at the U-turn of said main tube assembly, the bottom end of said seat tube being provided with a bracket for mounting the chain wheel and crank assembly and the top end thereof being provided with a clamp for mounting the saddle, a pair of support tubes, one connecting the top end and the other connecting the bottom end of said seat tube with the stem of said main tube assembly, and a pair of seat stay tubes connecting the top end of said seat tube with the two tine members of said main tube assembly. The invention will now be described, by way of illustration only, with reference to the accompanying drawing, in which :- Fig. 1 shows a bicycle frame assembly according to an embodiment of the present invention; and Fig. 2 shows a bicycle fitted with the frame assembly shown in Fig. 1. As shown in the Figures the frame assembly consists of a main tube 1 and two rear stay tubes 2 and 3 welded together to form a tuning fork like configuration. The tubes 1, 2 and 3 are made from circular cross-section tubes of required dimensions which are then pressed in a power press using die blocks to impart the required oval shape to them. A head tube 4 is fixed at the front (free) end of tube 1 by welding. A seat tube 5 is fixed centrally and in between the rear stays 2 and 3 by welding. A bottom bracket tube 6 is fixed at the bottom end of seat tube 5 by welding. There is a top support tube 7, one end of which is fixed to the top portion of seat tube 5 and the other end thereof is fixed to the rear portion of main tube 1 by welding. There is a bottom support tube 8, one end of which is fixed to the bottom bracket 6 and the other end thereof is fixed to the rear portion of tube 1 by welding. Seat stay tubes 9 and 10 are fixed to the top portion of seat tube 5 and to the middle portions of the rear stay tubes 2 and 3 by welding. The free (rear) ends of the rear stay tubes 2 and 3 are provided with drop-outs 11 and 12 by welding for rear wheel mounting. Pivot pins 13 and 14 are welded vertically on rear stays 2 and 3 at suitable locations for rear brake mounting. A bridge plate 15 is welded across the seat stays 9 and 10 and another bridge plate 16 (see Fig. 2) is welded across rear stays 2 and 3 for rear mudguard mounting purpose. A clamp 17 is welded on the top end of the seat tube 5 to enable mounting of the saddle. Cable guides 18 and 19 are welded on top edges of tube 1 in-line, one on each end of the tube 1, through which the rear brake cable is guided. A cable stopper 20 is welded on the rear side of seat tube 5 and at a location above rear stay tubes 2 and 3, to hold the rear brake cable sleeve while fixing the brake assembly. In the frame assembly shown, the rear stays 2 and 3 are connected to almost the centre portion of the seat tube 5 leaving free space -along the chain path, and this facilitates easy removal of the chain, when required, without delinking. The main tube 1 and the rear stays 2 and 3 are aligned in a straight line thereby facilitating a straight path for the rear brake cable. This avoids one of the two bends existing in the rear brake cable mounting in the case of conventional frame assembly. Thus, the present invention reduces the brake cable operating friction, thereby enhancing the braking efficiency and reducing the force requirement on the brake lever. The present invention also eliminates the top tube existing in the conventional frames that connects the top ends of the seat tube and head tube, and because of this, elimination more leg space is created. Moreover, the operating height of the main tube from the ground is also reduced. All these enable easy getting on and getting down from the bicycle and make the riding more convenient for both the sexes. In the frame assembly according to the invention, since the main tube 1 and the rear stays 2 and 3 are of oval cross-section, the frame can sustain more vertical loading. Moreover, the frame r configuration imparts a unique appearance to the bicycle contributed by the proper positioning of main tube 1, rear stay tubes 2 and 3, top support tube 1, and the bottom support tube 8. We claim:- 1. A bicycle frame, comprising a main tube assembly with sn oval cross-section and having a tuning fork like configuration, the end of each tine member of said tube assembly being provided with a drop-out for mounting the rear wheel assembly and the other end thereof being provided with a head tube for mounting the front wheel assembly, a substantially vertical seat tube fixed centrally at the U-turr. of said main tube assembly, the bottom end of said seat tube being provided with a bracket for mounting the chain wheel and crank assembly and the top end thereof being provided with a clamp for mounting the saddle, a pair of support tubes, one connecting the top end and the other connecting the bottom end of said seat tube with the stem cf said main tube assembly, and a pair of seat stay tubes connecting the top end of said seat tube with the two tine merbers cf said main tube assembly. 2. A bicycle frame as claimed in "claim 1, wherein said support tubes are fixed on to said stem at a location near tc said U-turn. 3. A bicycle frame as claimed in claim. 1 or 2, wherein said seat tube together with said two support tubes define triangular configuration. 4. A bicycle frame as claimed in any of the preceding claims 1 to 3, wherein said seat stay tubes are fixed on to said tine members at a location substantially at the middle portion thereof. 5. A bicycle frame as claimed in any of the preceding claims 1 to 4, wherein a pivot pin is fixed vertically on each said tine member at a predetermined location for mounting the rear brake assembly. 6. A bicycle frame as claimed in any of the preceding claims 1 to 5, wherein a bridge plate is provided across said two seat stay tubes and another bridge plate across said two tine members for mounting the rear mudguard. 7. A bicycle frame as claimed in any of the preceding claims 1 to 6, wherein guide members are provided on top edge of said stem for guiding the rear brake cable. 8. A bicycle frame, substantially as herein described and illustrated with reference to the accompanying drawing. 3

Documents:

802-mas-1997 abstract.pdf

802-mas-1997 claims.pdf

802-mas-1997 correspondence others.pdf

802-mas-1997 correspondence po.pdf

802-mas-1997 description (complete).pdf

802-mas-1997 drawing.pdf

802-mas-1997 form-1.pdf

802-mas-1997 form-26.pdf