Attachment group of a pedal crank to the central axle of a bottom bracket of a bicycle transmission

摘要

The attachment group (8; 78) of a pedal crank (1; 1') to the central axle (4; 4'; 74) of the bottom bracket of a bicycle transmission, in which the axle (4; 4'; 74) defines an axial direction along its own rotation axis (X) and on it a first way (X₁) towards the centre of the axle (4; 4'; 74) and a second way (X₂) opposite the first (X₁), comprises a tension element (14; 84) in screwing engagement with the axle (4; 4'; 74) and in axial resting engagement with the pedal crank (1; 1'). The tension element (14; 84) comprises a first axial abutment surface (23; 123; 223; 323; 93), facing the first way (X₁) in the axial direction (X), for resting against a corresponding axial abutment surface (13) of the pedal crank (1; 1'), facing the second way (X₂) in the axial direction (X). The tension element (14; 84) further comprises a second axial abutment surface (24; 124; 224; 324; 94), facing the first way (X₁) in the axial direction (X), for resting against a corresponding axial abutment surface (9; 79) of the axle (4; 4'; 74), facing the second way (X₂) in the axial direction (X), and a third axial abutment surface (25; 425; 95), facing the second way (X₂) in the axial direction (X), for resting against a clamping element (26) which is in screwing engagement with the pedal crank (1; 1').;The resting between the first axial abutment surface (23; 123; 223; 323; 93) of the tension element (14; 84) and the axial abutment surface (13) of the pedal crank (1; 1') ensures the precision of the axial position of the tension element (14; 84) with respect to the pedal crank (1; 1'), whereas the resting between the second axial abutment surface (24; 124; 224; 324; 94) of the tension element (14; 84) and the axial abutment surface (9; 79) of the axle (4; 4'; 74) ensures the precision of the axial position of the tension element (14; 84) with respect to the central axle (4; 4'; 74); the stability of the attachment is ensured by the clamping element (26).