Front derailleur for a bicycle, comprising: - a movable body, provided with a chain guide configured to interact with a transmission chain of the bicycle and movable between a plurality of positions comprised between an inner position and an outer position; - a fixed body, adapted for being fixed to a part of frame of the bicycle; - an outer connection element hinged to the fixed body about a first articulation axis and hinged to the movable body about a second articulation axis; - an inner connection element hinged to the fixed body about a third articulation axis and hinged to the movable body about a fourth articulation axis; - a return member active between the movable body and the inner connection element to push said chain guide in said inner position; - an actuation arm hinged to the fixed body about said first articulation axis and comprising a fastener for a control cable arranged to move away from the first articulation axis on the opposite side with respect to the second articulation axis; - said fixed body, said movable body, said inner connection element and said outer connection element defining an articulated quadrilateral deformable by said return member to move said chain guide from the outer position to the inner position and deformable by said actuation arm to move said chain guide from the inner position to the outer position; - said actuation arm and said outer connection element being rigidly connected to make a rocker arm when the force exerted on said fastener is such as to determine a movement of the chain guide between the inner position and the outer position, said actuation arm rotating with respect to said outer connection element when the force exerted on said fastener is greater than the force necessary to hold the chain guide in the outer position; characterized in that it comprises an elastic member comprising a torsion spring arranged at said second articulation axis and active between said outer connection element and said actuation arm, said elastic member elastically yielding when a force applied to said actuation arm is greater than the force necessary to deform said articulated quadrilateral to take the chain guide into the outer position. - a movable body, provided with a chain guide configured to interact with a transmission chain of the bicycle and movable between a plurality of positions comprised between an inner position and an outer position; - a fixed body, adapted for being fixed to a part of frame of the bicycle; - an outer connection element hinged to the fixed body about a first articulation axis and hinged to the movable body about a second articulation axis; - an inner connection element hinged to the fixed body about a third articulation axis and hinged to the movable body about a fourth articulation axis; - a return member active between the movable body and the inner connection element to push said chain guide in said inner position; - an actuation arm hinged to the fixed body about said first articulation axis and comprising a fastener for a control cable arranged to move away from the first articulation axis on the opposite side with respect to the second articulation axis; - said fixed body, said movable body, said inner connection element and said outer connection element defining an articulated quadrilateral deformable by said return member to move said chain guide from the outer position to the inner position and deformable by said actuation arm to move said chain guide from the inner position to the outer position; - said actuation arm and said outer connection element being rigidly connected to make a rocker arm when the force exerted on said fastener is such as to determine a movement of the chain guide between the inner position and the outer position, said actuation arm rotating with respect to said outer connection element when the force exerted on said fastener is greater than the force necessary to hold the chain guide in the outer position;