Riviere or Paris Sport; Low end boomie bikes...
Your description of the Roger Riviere sounds exactly like a flat orange painted "Paris Sport" sitting in my shed. I hung onto it as an "extra" for when my relatives visit. Wingnutted and Simplex Prestige equipped; it shifts loudly and poorly. The dimpled Rigida rims are like cheese graters for the brake pads. The unmarked plastic wedge of a seat was immediately discarded for a Japanese "quilted" saddle that is much better on one's bottom. Mine came equipped with Mafac Racer centerpulls but with a non hooded; safety lever-already permanently installed, version of the levers. These safety levers actually seem to work better than the standard Weinmann/Dia Compe versions of the day! It weighs a ton, but it is a reminder of what forever altered the bicycling landscape in America.