WO2004020272A1

WO2004020272A1 - Bicycle fork and its manufacturing method

Info

Publication number: WO2004020272A1
Application number: PCT/IT2002/000557
Authority: WO
Inventors: Andrea Pesenti
Original assignee: Cammax S.A.
Priority date: 2002-08-29
Filing date: 2002-08-29
Publication date: 2004-03-11
Also published as: AU2002343206A1

Abstract

A bicycle fork with composite material structure provides that the terminal region (C) where the wheel axle is secured has a flat shape arranged in the vertical plane, with a seat (D) suitable to receive said axle and an external metal mesh (T) embedded in the resin matrix as last layer of the composite structure, inside said terminal region (C) there being secured a metal insert (W’) having a thickness equal to the internal width of the terminal region (C) and provided with a seat (E’) corresponding to the seat (D) formed in the composite structure. In this way the fork does not require a specific insert depending on the angles and sections of the arms, nor right and left inserts, whereby a single type of insert is suitable for any fork, furthermore since the insert is completely introduced inside the composite structure the aesthetical effect is assured and also a weight reduction is achieved thanks to the smaller size thereof.

Description

"BICYCLE FORK AND ITS MANUFACTURING METHOD"

The present invention relates to bicycle manufacturing, and in particular to a fork and its manufacturing method. It is known that in bicycles made from composite material (i.e. fibers joined by a resin matrix) there are still provided metal inserts suitable to perform specific comiecting functions. Typically, this is the case of the inserts arranged at the ends of the front and rear forks, on which inserts there are mounted the wheels by tightening the nuts arranged at the threaded ends of the wheel axle. The structure of prior art forks, illustrated in figs.1-3, includes a cylindrical top tube S and two bottom amis A obtained as a hollow integral composite structure (e.g. carbon fiber and epoxy resin), the arms A ending with a bottom opening in which there is secured a relevant metal insert W, usually of aluminum. Each insert W has a specific shape in that it consists of a substantially cylindrical top portion M and a substantially flat bottom portion F, in which there is formed the seat E for introducing the wheel axle, between which there is formed a rim R having a contour corresponding to the contour of the ends of arms A.

Moreover, between the two portions M, F there is an angle α in the transverse plane which makes up for the inclination of arms A so that the two seats E are aligned along a horizontal plane for the correct mounting of the wheel. Similarly, a second angle β is provided in the longitudinal plane between the axis of seat E and the axis of the top portion M for a correct orientation of seat E with respect to the fork.

All these features of inserts W lead to a series of drawbacks which can be summarized as follows: a) each insert is suitable only for the fork for which the relevant angles α, β have been calculated, whereby it does not properly fit on other forks; b) there are right and left inserts which can not be swapped; c) the top portion M must have a section corresponding to the ends of arms A; d) if the contour of the ends of arms A is not regular it will project or recede with respect to rim R with a negative aesthetical effect.

In the light of the above it is clear that these inserts have to be made in a great variety of shapes, which results in high manufacturing costs and problems in managing a spare parts stock, and they are potentially difficult to be mounted on the composite material structure of the fork.

Therefore the object of the present invention is to provide a fork and a relevant manufacturing method which are free from the above-mentioned drawbacks. This object is achieved by means of a fork wherein the metal insert is reduced to a minimum and is the same for any fork design. Other advantageous features of the present fork are disclosed in the subsequent claims.

The main advantage of the present fork is exactly that of not requiring a specific insert depending on the angles and sections of the arms, whereby a single type of insert is suitable for any fork. This results in a significant saving since the inserts are no longer right and left, nor do they have various sizes and inclinations.

A second advantage of this fork, and of its manufacturing method, is that the insert is completely introduced inside the composite structure whereby there are no problems in having it match with the end contour and the aesthetical effect is assured and even better than in a conventional fork.

Still another advantage of such a fork is the weight reduction achieved by reducing the size of the metal insert, which light as it may be is always heavier than the composite material. Further advantages and characteristics of the fork and of its manufacturing method according to the present invention will be clear to those skilled in the art from the following detailed description of an embodiment thereof, with reference to the annexed drawings wherein:

Figs.1-3 are front and side views of a conventional fork as described above; Fig.4 is a front view of a fork according to the invention with the relevant inserts; and

Fig.5 is a side view similar to the preceding view.

Referring to fιgs.4 and 5, there is seen that a fork according to the present invention consists of a composite material structure obtained in a substantially conventional way, with a top tube S and two anns A' at whose ends metal inserts W are introduced.

The novel aspects of this fork are concentrated in the terminal region C of arms A', which has a flat shape with a central seat D (similar to the above- mentioned seat E) and an external metal mesh T also embedded in the resin matrix as last layer of the composite structure.

The relevant inserts W have a simple rectangular shape with a seat E' corresponding to seat D (fig.5), and a flat section (fig.4) of thickness equal to the internal width of region C in which they are completely introduced and secured by gluing.

In order to mount the wheel the axle is thus introduced in seats D at the ends of arms A', whose terminal regions C are parallel, and the tightening of the nuts takes place directly onto the composite structure protected by the metal mesh T and internally reinforced by insert W.

In the light of the description above the manufacturing method is readily understood: a) the composite material structure is prepared through a conventional process, the terminal regions C of arms A' being shaped as described above; b) at each of said regions C there is applied as last layer a metal mesh T, which may be either pre-impregnated or applied dry and then manually coated with resin; c) the thus prepared fork is cured; d) inside each region C there is glued an insert W as described above.

It is clear that the above-described and illustrated embodiment of the fork according to the invention is just an example susceptible of various modifications.

In particular, though the description and the figures relate to a front fork it is obvious that what has been said also applies to a rear fork which will have a different shape, particularly in the terminal regions C which may have a seat D with an axis substantially inclined with respect to the fork axis since the latter is inclined with respect to the vertical direction.

Moreover, the materials to be used can be freely selected among those usually employed in this field, whereby inserts W are preferably of aluminum and mesh T of titanium or steel but any other combination is possible as well.

Claims

1. Bicycle fork with composite material structure of fibers joined by a resin matrix, characterized in that each terminal region (C) where the wheel axle is secured has a flat shape arranged in the vertical plane, with a seat (D) suitable to receive said axle and an external metal mesh (T) embedded in the resin matrix as last layer of the composite structure, and in that inside said terminal region (C) there is secured a metal insert (W) having a thickness equal to the internal width of the terminal region (C) and provided with a seat (E') corresponding to said seat (D) formed in the terminal region (C).

2. Bicycle fork according to claim 1, characterized in that the metal mesh (T) is of titanium.

3. Bicycle fork according to claim 1 or 2, characterized in that the metal insert (W) is of aluminum.

4. Method for manufacturing a bicycle fork according to one or more of the preceding claims, characterized in that it includes the following steps: a) preparing a composite material structure with one or more terminal regions (C) having a flat shape arranged in the vertical plane and a seat (D) suitable to receive the wheel axle; b) applying as last layer at said one or more terminal regions (C) a metal mesh (T), which may be either pre-impregnated or applied dry and then manually coated with resin; c) curing the thus prepared fork; d) gluing inside each of said terminal regions (C) a metal insert (W) having a thickness equal to the internal width of the region (C) and provided with a seat (E') corresponding to said seat (D).