Abstract: A bicycle lamp device comprises a concave reflector (1), and a light source disposed substantially of the focus of said reflector and constituted by the filament (7) of a bulb (5). Said reflector had at least one window (10) in its surface enabling a secondary beam to be emitted from said source, and the device is characterized by the fact that said reflector further includes at least one secondary mirror (9) fixed to the edge (8) of its inside face, and oriented in such a manner as to send rays from said source through said window (10), thereby increasing the solid angle of said secondary beam.