Multipurpose transmission mechanism for bicycle with quick assembly device

A transmission mechanism for a bicycle having a frame in which a bore is defined, the transmission mechanism comprising:

• a quick assembly device comprising a central shaft, which extends through the bore of the bicycle frame;
• threaded collars, which are respectively mounted to opposite end openings of the bore to rotatably support the central shaft in the bore;
• a clip bracket, which comprises two retention rings respectively located outside the end openings of the bore and fixedly mounted to the threaded collars;
• and at least one clip that is mounted to the clip bracket to be movable between a first position and a second position;
• and
• a multi-mode mechanism, which is supported and fixed by the quick assembly device and in operative coupling with the clip in order to switch the bicycle among multiple modes of pedaling according to the switching of the clip between the first and second positions;
• wherein the clip bracket comprises downward extensions from the retention rings and a rear support block mounted between the downward extensions, the clip being movably mounted to the rear support block:
• and
• wherein the clip is rotatably mounted to a first support block, the first support block being mounted to the rear support block of the clip bracket.