| 摘要 |
A bicycle wheel rim (1) has a transverse section which comprises a central part (3, 4) pointing towards the wheel axis and two sides (5) each having an active part (13, 14) for engagement by a brake block (12). This active part comprises a circular curved part (14) which is concave outwards and has its centre of curvature separated from the axis of the wheel rim by a radius which is less than the radius of the mid-point of the active part of the side (5). A second radially external part (13) of the active part of each side (5) is in the form of a circular arc which is convex outwards and is connected to the first concave outwards part (14). This shaping of the side (5) of the wheel rim (1) guarantees uniform wear of the brake block (12) and a high uniform specific braking pressure on the block. <IMAGE>
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