Front derailleur of bicycle

A front derailleur of a bicycle comprising

• a retaining ring disposed on a bottom end of a seat post, the retaining ring including two coupling seats symmetrically fixed thereon to axially connect with a pushing mechanism, and the pushing mechanism being comprised of a cable rack, a limiting stem, a connecting rod set, a guiding loop, an axial pillar, an assembling bracket, and a guide plate, the coupling seat including the connecting rod set attached thereon, and the connecting rod set including a first connecting rod, a second connecting rod, a third connecting rod, and a fourth connecting rod, a shaft, and the guiding loop, characterized in that the coupling seat includes a first hole formed on a bottom end of a side thereof so that a first screw inserts through a first bore of the cable rack and a turning spring to screw with the first hole of the coupling seat, and includes two first tabs mounted on top ends thereof respectively to connected with the axial pillar axially.