In the Durbuy region there are many signposted mountain bike trails of different levels. At the Pré Géoris car park just outside Durbuy center you will find a sign with the most important routes that start there (see photo), but if you want more detail, it is best to visit the Tourist Office. They also sell tickets, if you’d like.
You will also find many downloadable routes in the area on the website of Famenne à Vélo.