The calculated distance (air line) between Roquebrune-Cap-Martin and Grenoble is approximately 131 miles respectively 211 kilometers.
By car or train, the actual journey to Grenoble is certainly longer, as only the direct route (as the crow flies) between Roquebrune-Cap-Martin and Grenoble has been calculated here.
Air line (approximately)
211 kilometers
114 nautical miles