A bicycle rear derailleur comprising: a base member mountable to a bicycle frame; a movable member movably coupled to the base member; a chain guide assembly rotatably connected to the movable member for rotation about a rotational axis; a guide wheel rotatable about the rotational axis; a biasing element configured and arranged to bias the chain guide assembly for rotation in a first rotational direction about the rotational axis with respect to the movable member; and a fluid damper comprising a fluid cavity containing a volume of fluid, the fluid damper being disposed at a connection of the chain guide assembly and the movable member and comprising a shaft, the shaft being rotatable about the rotational axis and configured to apply a damping force to the chain guide assembly when the chain guide assembly rotates in a second rotational direction opposite to the first rotational direction, wherein the fluid cavity comprises a damping chamber arranged to provide the damping force and a return chamber in fluid communication with the damping chamber, wherein the shaft comprises a vane radially extending from the shaft and dividing the fluid cavity to define the damping chamber and the return chamber on opposite sides of the vane, wherein the bicycle rear derailleur further comprises: a first guide member rotationally fixed to the shaft, disposed between the movable member and the guide wheel, the guide wheel being freely rotatable; and a second guide member rotationally fixed to the first guide member such that the guide wheel is disposed between the first and second guide members, characterized in that the bicycle rear derailleur further comprises: a first guide fixing member configured to affix the second guide member to the shaft, the first guide fixing member contacting both the second guide member and the shaft; and a closure mechanism configured to create a first seal along a wall of the fluid cavity, the shaft being configured to create a second seal with an opening of the closure mechanism. a base member mountable to a bicycle frame; a movable member movably coupled to the base member; a chain guide assembly rotatably connected to the movable member for rotation about a rotational axis; a guide wheel rotatable about the rotational axis; a biasing element configured and arranged to bias the chain guide assembly for rotation in a first rotational direction about the rotational axis with respect to the movable member; and a fluid damper comprising a fluid cavity containing a volume of fluid, the fluid damper being disposed at a connection of the chain guide assembly and the movable member and comprising a shaft, the shaft being rotatable about the rotational axis and configured to apply a damping force to the chain guide assembly when the chain guide assembly rotates in a second rotational direction opposite to the first rotational direction, wherein the fluid cavity comprises a damping chamber arranged to provide the damping force and a return chamber in fluid communication with the damping chamber, wherein the shaft comprises a vane radially extending from the shaft and dividing the fluid cavity to define the damping chamber and the return chamber on opposite sides of the vane, wherein the bicycle rear derailleur further comprises: a first guide member rotationally fixed to the shaft, disposed between the movable member and the guide wheel, the guide wheel being freely rotatable; and a second guide member rotationally fixed to the first guide member such that the guide wheel is disposed between the first and second guide members, characterized in that the bicycle rear derailleur further comprises: a first guide fixing member configured to affix the second guide member to the shaft, the first guide fixing member contacting both the second guide member and the shaft; and a closure mechanism configured to create a first seal along a wall of the fluid cavity, the shaft being configured to create a second seal with an opening of the closure mechanism. a first guide member rotationally fixed to the shaft, disposed between the movable member and the guide wheel, the guide wheel being freely rotatable; and a second guide member rotationally fixed to the first guide member such that the guide wheel is disposed between the first and second guide members, characterized in that the bicycle rear derailleur further comprises: a first guide fixing member configured to affix the second guide member to the shaft, the first guide fixing member contacting both the second guide member and the shaft; and a closure mechanism configured to create a first seal along a wall of the fluid cavity, the shaft being configured to create a second seal with an opening of the closure mechanism. a first guide fixing member configured to affix the second guide member to the shaft, the first guide fixing member contacting both the second guide member and the shaft; and a closure mechanism configured to create a first seal along a wall of the fluid cavity, the shaft being configured to create a second seal with an opening of the closure mechanism.