Wheel rim

Abstract

A bicycle wheel rim including an outer annular portion adapted to receive a tire and an inner peripheral radial portion that has both a plurality of circumferentially arranged spoke openings and a braking surface on this portion.

Claims

1. A bicycle wheel rim comprising an outer annular portion adapted to receive a tyre, and a flange extending radially inwardly from an outer surface of said outer annular portion, said flange having a plurality of circumferentially arranged spoke openings and a braking surface thereon, said braking surface being positioned between said plurality of circumferentially arranged spoke openings and said outer surface.

2. The bicycle wheel rim of claim 1, wherein the outer annular portion and the inner peripheral radial portion form a Y shape.

3. The bicycle wheel rim of claim 1, wherein the inner peripheral radial portion projects towards a hub portion of the bicycle wheel.

4. The bicycle wheel rim of claim 1, wherein the spoke openings are shaped to receive a head of a spoke.

5. The bicycle wheel rim of claim 2, wherein the inner peripheral radial portion projects towards a hub portion of the bicycle wheel.

6. The bicycle wheel rim of claim 2, wherein the spoke openings are shaped to receive a head of a spoke.

7. The bicycle wheel rim of claim 3, wherein the spoke openings are shaped to receive a head of a spoke.

8. The bicycle wheel rim of claim 5, wherein the spoke openings are shaped to receive a head of a spoke.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) By way of example, an embodiment of the invention is described more fully herein with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a cross section of a bicycle rim of the prior art;

(3) FIG. 2 shows a cross section of a bicycle rim of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) Aerodynamic bicycle wheels known in the prior art are made from materials such as carbon fibre to create bulbous cross sectional shapes as shown in FIG. 1. To a lesser extent such bicycle rim shapes have also been made previously from aluminium however such rims are generally heavy in comparison to their carbon fibre embodiments.

(5) The bicycle wheel rim 5 of the present invention has outer annular portion 7 adapted to receive a tyre. The tyre can be of clincher type or a tubular type. In the event of a clincher type tyre being used the outer annular portion 7 would include a pair of opposing flanges or beads shaped to engage with a bead of the clincher tyre (not shown). Such arrangements are well known by those skilled in the art.

(6) The bicycle wheel rim 5 further includes an inner peripheral radial portion 10, projecting from the outer surface 8 of the outer annular portion 7 towards a hub section (not shown) of the bicycle wheel. Arranged circumferentially about the inner peripheral radial portion 10 is a plurality of spoke openings 11 adapted to receive an end of a spoke 15.

(7) The spoke 15 engages with the peripheral radial portion 10 by insertion of the spoke 15 though the opening 11 so that the spoke head 17 abuts the portion 18 of the peripheral radial portion 10. As such, the spoke 15 has at its opposite end a threaded section for insertion and attachment to a suitably configured hub flange (not shown).

(8) Alternatively, the threaded section of the spoke 15 may be attached to an adaptor spoke section, so that traditional hub flange fittings may be used. Alternatively, other methods of spoke attachment known to those skilled in the art of wheel building can be utilized without departing from the scope of the invention.

(9) The peripheral radial portion 10 is the braking section of the wheel rim 5, with both sides (25 and 26) of the peripheral radial portion 10 machined or constructed to act as a braking surface. The brakes of a bicycle fitted with the wheel rims 5 have the braking shoes positioned lower than would be used for a traditional bicycle wheel rim, that is where the braking surface of the wheel rim is immediate adjacent the tyre. This may require the use of longer brake arms or cantilever type brakes rather than calliper style brakes.

(10) The surface 8 of the outer annular portion 7 and or the lower surface 28 of the peripheral radial portion 10 can feature a plurality of surface features designed to create a turbulent boundary layer when the wheel travels through air to reduce aerodynamic drag on the wheel.

(11) This then has significant advantages, the first of which is that the positioning of the thicker braking surface of the peripheral radial portion 10 is closer towards the hub of the wheel and that the outer annular portion 7 is as a result lighter. The movement of the mass towards the centre of the wheel provides for a lower rotation mass and as a consequence a lower rotational inertia. As such the wheel is faster to spin up.

(12) A further advantage is in the improvement in braking power. By moving the braking surfaces (25 and 26) inwards towards the centre and away from the outer annular portion 7, there is less opportunity for debris such as mud and water to build up on them. Indeed, the outer annular portion 7 can be manufactured quite thin compared to a box section rim as there is no need to have machined braking surfaces on either side, the outer annular portion 7 need only be strong enough to support the outward pressure of the clincher tyre attached thereto as well as provide suitable structural strength to the wheel. This is in contrast to traditional box section clincher rims.

(13) Moreover, as the breaking surface is moved away from the outer annular portion 7 then heat build up in the wheel, a common problem associated with carbon fibre clinchers rims, is less of an issue. The heat build up brought about by braking friction is instead localised to the braking surfaces (25 and 26) on the peripheral radial portion 10. Any build up of heat that might arise does not thus affect the rims capacity to restrain any clincher tyre thus reducing the possibility of clincher tyre blowouts.

(14) The braking surfaces (25 and 26) act more like disc brake surfaces. Also, the brake pads used by the brakes can be larger therefore increasing braking power.

(15) Metals, such as aluminium can be used to make such rims of the present invention, either from extrusion or casting. This then produces a wheel of suitable strength, while also providing a degree of aerodynamics. Carbon fibre construction may also be used

(16) Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures can be made within the scope of the invention, which is not to be limited to the details described herein but it is to embrace any and all equivalent devices and apparatus.