The present invention relates to a bicycle and to a casing for a bicycle.

Bicycle frames, which connect together the wheels of a bicycle and to which are attached equipment such as saddles and pedals, are conventionally made of tubing or other similar material which provides the structural strength of the frame and defines the exterior surface of the bicycle's frame region. This arrangement has several disadvantages. The exterior of the bicycle cannot easily be styled to a desired shape (either for aerodynamic reasons or to follow current fashions) because to do so would require the frame itself to be shaped. Due to considerations of weight, this is only possible if the frame is made of a (typically expensive) material having a good strength-to-weight ratio. Also, the external surface area of the frame is relatively small so there is little room for decorative patterns or advertising to be applied to the frame. Also, most frames are made of metal members joined together and work is needed after joining has taken place to finish the exterior of such frames by smoothing the joints and removing rust; otherwise the joints are unsightly and impair the bicycle's aerodynamic qualities.

According to the present invention there is provided a bicycle comprising an inner, structural frame portion and an outer, casing portion located externally of the frame portion.

This arrangement allows the disadvantages mentioned above to be overcome. The casing portion can easily be styled to a desired shape without any need to alter the structural frame portion. For example, the casing portion can be styled as an aerodynamic fairing around the frame portion. Alternatively, the casing portion can be styled to an attractive design, for example to

resemble the frame of a bicycle made of expensive, high- strength materials or to simulate apparatus such as suspension on the bicycle. The casing portion can easily be styled to include relatively large exterior surface portions, preferably presenting substantially vertical surfaces, to receive patterns or advertising material.

Preferably, parts of the frame portion are substantially enclosed or surrounded by the casing portion and encased by it to prevent them being exposed once the bicycle is assembled. Such parts may be left in an unfinished or semi-finished state without detracting from the bicycle's aesthetic or aerodynamic properties. Thus the cost of finishing the frame portion is reduced. Similarly, the casing portion can cover the bolts, bolt holes, etc which are normally present on a bicycle. This has similar aesthetic and aerodynamic advantages. Further aerodynamic advantages can be achieved by configuring the casing portion to incorporate aerodynamically advantageous features such as spoilers.

The casing may include features intended to act as one or more mudguards. Preferably, for lightness, such features can be incorporated in the said aerodynamically advantageous features.

The casing portion may enclose or surround (or substantially enclose or surround) all of the frame portion, including, for example, the bicycle's front and/or rear forks. The majority of the frame portion may be encased in a single cavity of the casing portion or alternatively each member of the frame portion may be received in an individual channel inside the casing portion.

The casing portion preferably comprises two complementary casing members which are located on opposite sides of the frame portion and are joined together or to the frame portion. Additional casing members may also be used.

The casing portion suitably includes an exterior wall and locating means, for example projections or spacing nibs, provided on the interior surface of the casing portion. These preferably bear on the frame portion to space the interior surface of the wall from the frame portion. The locating means are preferably spaced apart from each other.

The casing portion is preferably held around the frame portion only by fastening means that fasten solely to the casing portion. There is preferably no direct fastening of the casing portion to the frame portion.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side view of a bicycle according to the invention;

Figure 2 is an exploded perspective view of part of the bicycle of Figure 1; and

Figure 3 is a side view of a second embodiment of a bicycle according to the invention.

Figures 1 and 2 show a bicycle having an inner frame 1 and outer casings 2 and 3. When assembled, as shown in Figure 1, the casings surround parts of the inner frame and their outer walls 21,31 define the majority of the exterior surface of the bicycle's frame region.

The frame 1 is made of steel tubing welded together in the conventional way. It includes flat-sided rear stays 12,13 which meet the seat tube 14 near its upper end and are supported by tubular support stays 15,16 which converge downward from the rear stays to the seat tube 14. Those parts of the frame which are to be encased by the casings are left unfinished or semi-finished. In the

embodiments of Figures 1 and 3 parts of the front forks 11 and the rear stays 12,13 are not encased and these must be finished in the normal way. However, all of the frame could be encased to avoid the need for any such finishing work. Where the chain and gears are encased the risk of the rider being dirtied by oil from the chain is reduced.

The casings 2,3 are made of plastics material (for example ABS, styrene or polypropylene) injection moulded or vacuum formed to the required shape. Such casings can be manufactured relatively cheaply. The casings are relatively light and resilient and provide a smooth, aerodynamic exterior surface to the bicycle. This is easier for the user to clean than the complex shapes of conventional bicycles. As shown in Figure 2, the casings are of complementary shapes and are joined around the frame with self-tapping screws 4. These pass through bores 22 in casing 2 and into projections 32 in casing 3 to draw the casings together around the frame as the screws are tightened. Alternatively, the casing members could be snap-fitted together. There is preferably no direct fastening of the casing to the frame. Casing 3 includes spaced-apart projecting nibs 33 which bear against the exterior of the frame when the casing is assembled to space the outer walls 21,31 of the casing away from the frame and to locate the casing in place around the frame. The nibs 33 mate with co-operating holes in casing 2 to ensure correct alignment of the casings and a flush fit at the meeting edges of the casings when they are assembled.

Webs 23,34 are provided for aesthetic reasons and to strengthen the casings. Ports are provided in the assembled casing to allow equipment such as, for example, the crank shaft 6, the seat post 7 and brake cables to pass through the casing. Apart from these ports the interior of the casing is substantially sealed (to protect the frame inside) except for a drain hole 24 and

a bore 35 which allows access to the seat-post locking bolt 8 to allow the height of the saddle to be adjusted without the casing being removed. Thus, the casing protects the encased parts of the frame from corrosion. A spoiler or simulated spoiler 25,36 is provided for aerodynamic and/or aesthetic purposes. This is positioned so that it also serves as a rear mudguard.

In the embodiment of Figure 1 each tube of the frame passes through an individual channel in the assembled casing, and a central opening 5 is defined through the casing. In the embodiment of Figure 3 the assembled casing defines a single interior cavity which receives the majority of the frame.

Secondary casings 9 are provided around the front forks. These may be styled aesthetically, for example to simulate suspension apparatus, or aerodynamically.

The casings provide relatively large external surfaces, in particular substantially vertical surfaces, to which may be applied decorative patterns or advertisements. The casings may be made of transparent material to protect decoration (such as decals or paintwork) applied to the frame itself whilst allowing the decoration to be seen. The casings may have reflective or pearlescent portions affixed to their exterior surfaces or moulded into them. These increase the safety of the bicycle by making it more visible, especially in the dark.

The casings may be a structural element of the bicycle, allowing the size, and therefore weight, of the tubes of the frame to be reduced.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof it will be understood by those skilled in the art that various changes in form and details may be made

without departing from the spirit and scope of the invention.