GB2101541A - Wheel rims - Google Patents

Abstract

A wheel rim, e.g. for bicycles, is formed on one or both side walls with a plurality of grooves, arranged preferably in first sets 5 and second sets 6 which alternate around the rim, the grooves in the first sets being oppositely inclined to the radial to those in the second sets. The grooves provide a surface roughness, for improved braking in the wet. Alternatively all grooves may be inclined in the same sense to the radial. <IMAGE>

Description

SPECIFICATION Wheel rims This invention relates to wheel rims and is particularly although not exclusively concerned with wheel rims for bicycles.

Bicycle brakes conventionally comprise brake blocks which are adapted to engage opposite side walls of a wheel rim, thereby to brake movement of the wheel rim. Both wheel rims and brake blocks have been made of various materials which, although affording good performance under dry conditions, tend to suffer from various degrees of reduced efficiency in wet conditions.

For example, most brake blocks at the present day are of rubber, giving satisfactory performance in the dry with most types of wheel rim. However, where the wheel rim is of steel (usually brightly chrome steel), rubber brake blocks can be almost useless in the wet. On the other hand, brake blocks of leather can be reasonably effective in the wet with steel wheel rims, but virtually useless with aluminium wheel rims.

The present invention aims to provide a wheel rim which may be improved in the foregoing respect, in that it may afford improved braking both under dry and wet conditions for a wide variety of materials for both wheel rim and associated brake blocks.

According to one aspect of the present invention, there is provided a wheel rim which is formed on at least one side wall thereof with a plurality of grooves extending outwardly of the rim, Although the grooves must have at least a component of extent in a direction radially of the wheel rim, it is not essential that they extend exactly along radii thereof.

The purpose of the grooves is to allow expulsion of water radially of the wheel rim during a braking action in wet weather, when a brake block is applied to said at least one side wall. Such water may otherwise form a surface layer between the side wall and the brake block, thereby impairing or obviating the braking action.

In a preferred arrangement, the grooves are each arranged at a constant angle to respective radii of the wheel rim, such that the grooves have a component of extent in a direction of rotation of the wheel rim.

In an especially advantageous arrangement, the grooves are arranged in two series of sets of grooves, the grooves of one series having a component of extent in one direction of rotation of the wheel rim, the grooves of the other series having a component of extent in the opposite direction of rotation of the wheel rim, and the sets of grooves of one series alternating with the sets of grooves of the other series. Such a wheel rim has the advantage that it is equally effective in either direction of rotation of the wheel rim. Thus, depending upon the direction of rotation, a respective one of the series of grooves will be of major effect, in that the rotational speed of the wheel rim will assist ejection of the water from the grooves of that series.

Preferably, said grooves are provided on two opposite side walls of the wheel rim.

In a preferred embodiment, the wheel rim is a wheel rim of a bicycle, and the invention extends to bicycle wheels incorporating such wheel rims, and also to bicycles having such wheels.

The invention also provides a wheel rim in accordance with said one aspect of the present invention, in combination with a brake mechanism adapted to apply a brake block or other braking member to said at least one wall.

For a better understanding to the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 is a side view of a preferred wheel rim in accordance with the invention; Figure 2 is an enlarged detail view thereof; and Figure 3 shows a cross-section of the wheel rim.

The illustrated wheel rim 1 is of fairly conventional cross-section, in that it comprises two side walls 2 connected by a web 3. In use, spokes radiating from a hub are secured to the web 3, to make up a bicycle wheel.

The important feature about the illustrated wheel rim is the provision of grooves 4 upon each side wall 2. The grooves 4 are arranged in sets 5 which alternate around the rim with sets 6 of grooves 4. The sets 5 of the grooves form a first series, and the sets 6 of grooves form a second series.

It may be seen that the grooves 4 of the first sets 5 all extend in the same direction, at a constant angle to respective radii of the wheel rim 1. Thus, they each have a component of extent in a clockwise (as seen) direction of rotation of the wheel rim 1. The grooves 4 of the second sets 6 are similarly inclined at the same angle to respective radii of the wheel rim, but in the opposite, anti-clockwise (as seen) direction of rotation of the wheel rim.

Thus the grooves 4 each extend outwardly of the wheel rim 1, and extend partly in a radial and partly in a tangential direction. In use, a respective brake block is applied to each of the side walls 2, in order to achieve braking. Because of the provision of the grooves 4, the surface of the side walls 2 has an overall roughness, which assists the braking effect, even under dry conditions.

However, what is more important is that, under wet conditions, any water that is caught between the brake blocks and the side walls 2 is squeezed into the grooves 4, and expelled outwardly from the wheel rim 1, under both centrifugal force and because of the angular velocity of the wheel rim 1, rather than being trapped between the wheel rim 1 and the respective brake blocks, which would tend to impede or even obviate the braking action.

Thus, the illustrated wheel rim 1 may be used to provide completely safe braking both under dry and wet conditions, largely irrespective of the materials of the wheel rim 1 and of the associated braking blocks oF other braking members. For example, therefore, the wheel rim may be either of bright chromed steel (which is especially favoured) or of aluminium, and the respective braking blocks may be of rubber of leather. The invention is especially advantageous wherein the wheel rim 1 is used with brake blocks of rubber, which is relatively cheap and effective under dry conditions, and the wheel rim 1 is of bright chrome steel, which is especially favoured because of its attractive appearance. As is outlined above, in previously known rims having this combination of materials, braking in the wet is severely affected.

The illustrated pattern of the grooves 4 is especially advantageous, as the wheel rim 1 may be fitted for use with its axis extending in any one of two directions. However, it may be appreciated that the grooves 4 may alternatively be arranged in other patterns. For example, all of the grooves 4 may have components of extent in the same direction of rotation of the wheel rim 1, in which case care must be taken to mount the wheel rim 1 in the correct orientation, in use.

CLAIMS (Filed on 7 May 1982) 1. A wheel rim which is formed on at least one side wall thereof with a plurality of grooves extending outwardly of the rim.

2. A wheel rim according to Claim 1, wherein the grooves are each arranged at a constant angle to respective radii of the wheel rim, such that the grooves have a component of extent in a direction of rotation of the wheel rim.

3. A wheel rim according to claim 2, wherein the grooves are arranged in two series of sets of grooves, the grooves of one series having a component of extent in one direction of rotation of the wheel rim, the grooves of the other series having a component of extent in the opposite direction of rotation of the wheel rim, and the sets of grooves of one series alternating with the sets of grooves of the other series.

4. A wheel rim according to Claim 1, 2 or 3, wherein said grooves are provided on two opposite side walls of the wheel rim.

5. A wheel rim substantially as hereinbefore described with reference to the accompanying drawings.

6. A bicycle wheel having a wheel rim according to any preceding claim.

7. A wheel rim or bicycle wheel according to any preceeding claim, in combination with a brake mechanism adapted to apply a brake block or other braking member to said at least one wall.

8. A combination according to Claim 7, wherein said wheel rim is of bright chrome steel and said brake block or other braking member is of rubber.

9. A bicycle having a wheel according to Claim 6 or a combination according to Claim 7 or 8.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. braking blocks oF other braking members. For example, therefore, the wheel rim may be either of bright chromed steel (which is especially favoured) or of aluminium, and the respective braking blocks may be of rubber of leather. The invention is especially advantageous wherein the wheel rim 1 is used with brake blocks of rubber, which is relatively cheap and effective under dry conditions, and the wheel rim 1 is of bright chrome steel, which is especially favoured because of its attractive appearance. As is outlined above, in previously known rims having this combination of materials, braking in the wet is severely affected. The illustrated pattern of the grooves 4 is especially advantageous, as the wheel rim 1 may be fitted for use with its axis extending in any one of two directions. However, it may be appreciated that the grooves 4 may alternatively be arranged in other patterns. For example, all of the grooves 4 may have components of extent in the same direction of rotation of the wheel rim 1, in which case care must be taken to mount the wheel rim 1 in the correct orientation, in use. CLAIMS (Filed on 7 May 1982)

1. A wheel rim which is formed on at least one side wall thereof with a plurality of grooves extending outwardly of the rim.

2. A wheel rim according to Claim 1, wherein the grooves are each arranged at a constant angle to respective radii of the wheel rim, such that the grooves have a component of extent in a direction of rotation of the wheel rim.

3. A wheel rim according to claim 2, wherein the grooves are arranged in two series of sets of grooves, the grooves of one series having a component of extent in one direction of rotation of the wheel rim, the grooves of the other series having a component of extent in the opposite direction of rotation of the wheel rim, and the sets of grooves of one series alternating with the sets of grooves of the other series.

4. A wheel rim according to Claim 1, 2 or 3, wherein said grooves are provided on two opposite side walls of the wheel rim.

5. A wheel rim substantially as hereinbefore described with reference to the accompanying drawings.

6. A bicycle wheel having a wheel rim according to any preceding claim.

7. A wheel rim or bicycle wheel according to any preceeding claim, in combination with a brake mechanism adapted to apply a brake block or other braking member to said at least one wall.

8. A combination according to Claim 7, wherein said wheel rim is of bright chrome steel and said brake block or other braking member is of rubber.

9. A bicycle having a wheel according to Claim 6 or a combination according to Claim 7 or 8.