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
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

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/