Bicycle rear derailleur device , comprising: a base member arranged to be anchored to the bicycle frame; a movable member ; a linking member connecting the base member to the movable member , so that said movable member moves laterally relative to the base member between a retracted position and an extended position; a chain guide assembly , for guiding a transmission chain by selectively aligning it with one between a plurality of sprockets, comprising two independent chain cages: a tension cage and a guiding cage ; the tension cage being pivotably coupled to the movable member to be able to rotate about a pivot axis (P), and provided with a tension pulley that can rotate freely around a tension pulley rotation axis (T) parallel to said pivot axis (P); the guiding cage being provided with a guiding pulley that can rotate freely around a guiding pulley rotation axis (G) parallel to said pivot axis (P), where the guiding cage is movably coupled to the tension cage , wherein the distance between the guiding pulley and the tension pulley can vary; and a biasing member provided between the movable member and the tension cage which, in order to keep the chain in tension, forces the tension cage to pivot with respect to the movable member around the pivot axis (P) in the direction of bicycle pedalling rotation (C); characterized in that said chain guide assembly comprises coupling means , which allow to alternate the configuration of said chain guide assembly in a selective and reversible way, between at least two operation modes, a maintenance mode wherein the distance between the guiding pulley and the tension pulley can vary; and a working mode wherein the approach between the guiding cage and the tension cage is prevented, thus limiting the minimum distance between the guiding pulley and the tension pulley , so that the guiding cage forced by the tension in the chain, moves jointly with the tension cage . a base member arranged to be anchored to the bicycle frame; a movable member ; a linking member connecting the base member to the movable member , so that said movable member moves laterally relative to the base member between a retracted position and an extended position; a chain guide assembly , for guiding a transmission chain by selectively aligning it with one between a plurality of sprockets, comprising two independent chain cages: a tension cage and a guiding cage ; the tension cage being pivotably coupled to the movable member to be able to rotate about a pivot axis (P), and provided with a tension pulley that can rotate freely around a tension pulley rotation axis (T) parallel to said pivot axis (P); the guiding cage being provided with a guiding pulley that can rotate freely around a guiding pulley rotation axis (G) parallel to said pivot axis (P), where the guiding cage is movably coupled to the tension cage , wherein the distance between the guiding pulley and the tension pulley can vary; and a biasing member provided between the movable member and the tension cage which, in order to keep the chain in tension, forces the tension cage to pivot with respect to the movable member around the pivot axis (P) in the direction of bicycle pedalling rotation (C); characterized in that said chain guide assembly comprises coupling means , which allow to alternate the configuration of said chain guide assembly in a selective and reversible way, between at least two operation modes, a maintenance mode wherein the distance between the guiding pulley and the tension pulley can vary; and a working mode wherein the approach between the guiding cage and the tension cage is prevented, thus limiting the minimum distance between the guiding pulley and the tension pulley , so that the guiding cage forced by the tension in the chain, moves jointly with the tension cage . <EOS>