Dual lever type derailleur gear unit for a bicycle

A derailleur gear unit comprising:

• a supporting base (50);
• a pivot base (44) fixedly mounted on said supporting base (50);
• a ratchet wheel (43) rotatably mounted around said pivot base (44) and including an outer periphery formed with a plurality of teeth (430);
• a retaining disk (40) fixedly mounted around said pivot base (44) and abutting on said ratchet wheel (43), and a shank (41) extending outwardly from an outer periphery of said retaining disk (40) and formed with a catch (411) extending laterally;
• a first shifting lever (10) including a first end portion (11) located adjacent to said shank (41) of said retaining disk (40), a mediate portion rotatably mounted around said pivot base (44) and abutting on said retaining disk (40), and a second end portion (13);
• a pawl member (20) pivotally mounted on said first end portion (11) of said first shifting lever (10) and including an arcuate guiding track (21) slidably abutting on said catch (411), and a detent (22) detachably meshing with one of said teeth (430) of said ratchet wheel (43);
• a second shifting lever (30) including a first end portion (302) pivotally mounted around said pivot base (44) and abutting on said first shifting lever (10) and a second end portion (304);
• and
• a pushing rod (33) mounted on said first end portion (302) of said second shifting lever (30), located radially opposite to said detent (22) of said pawl member (20), and detachably meshing with one of said teeth (430) of said ratchet wheel (43).