VISITWallonia.be offers a collection of cycyling loops for MTB and touring bikes :
https://visitwallonia.be/fr-be/3/jaime/wallonie-a-velo/carte-des-balades-a-velo
Bike rental in Flanders and Brussels
A list of locations that rent bikes:
https://www.cyclinginflanders.cc/plan-your-stay/bike-rental
Bikes for rental in several locations in Flanders and Brussels:
https://www.cctbikerental.com/location/bike-rentals-flanders-ardennes/
Road bikes for rental from Livelo:
https://www.livelo.cc/collections/brussels-road-bike-rental
https://www.livelo.cc/collections/road-bike-rental-ghent
Road and gravel cycling loops from Flanders
Road and gravel cycling loops for the enthusiast cyclist
Routes based on the node points from Flanders
Cycle touring routes based on the node points (Fietsknooppunten).
Cycle highways
Cycle highways – a network of fast cycling routes present in Flanders and Brussels Region.
RAVeL (Réseau Autonome des Voies Lentes)
RAVeL (Réseau Autonome des Voies Lentes) – a network of greenways from Wallonia that were built in place of ancient railway lines and towing paths along waterways.
MTB loops from Flanders
MTB routes with various difficulty levels, grouped by location. They can be downloaded and imported in navigation apps like Komoot, RouteYou, and others.
https://www.sport.vlaanderen/ik-wil-mountainbiken/vind-een-mountainbikeroute/
Cycling in Belgium 