A bicycle derailleur comprises a base member adapted to be mounted to a bicycle, a movable member movably coupled to the base member, a chain guide coupled to the movable member for rotation around a rotational axis, a resistance applying element that applies resistance to rotational movement of the chain guide, and a resistance control element. The resistance control element applies a force to the resistance applying element in a direction that is non-parallel with the rotational axis, without any manual operations, to prevent a reduction in the resistance to rotational movement of the chain guide applied by the resistance applying element.