The calculated distance (air line) between Saint-Quentin-en-Yvelines and Roubaix is approximately 143 miles respectively 229 kilometers.
By car or train, the actual journey to Roubaix is certainly longer, as only the direct route (as the crow flies) between Saint-Quentin-en-Yvelines and Roubaix has been calculated here.
Air line (approximately)
229 kilometers
124 nautical miles