I build bike + train loops in France by crossing OpenStreetMap with the official cycling-route reference (RVM / Réseau vélo et marche). Two points I’d value the community’s view on: at which level the identity (ref) of a multi-level superroute should live, and whether the emerging ref:FR:RVM tag (which carries the RVM id and gives an exact OSM↔RVM join key) is worth spreading. Full write-up (FR): https://tisseurdevoies.fr/articles/openstreetmap-veloroutes-retour-experience