I’ve been in Stavanger for a few years but not found any offroad riding worth talking about yet, I’ve heard about some trails but it’s not the sort of proper mountain adventures like youd get in wales, the peaks, lakes or Scotland. The terrain around here tends to be either super steep or flattish gravel tracks, and not much in between. If you’re in to it the road riding is great though if you head to the hills in the southeast and east (especially Lysefjord area, or Suleskard from the Sirdal valley), or a bit further south along the coast around places like Jossingfjord. It is hilly though! It’s much flatter along the coast immediately south of stavanger Loads of hiking close to here, you don’t need to join the crowds at the popular spots of Preikestolen or Kjerag boulder if that’s not your sort of thing, again the Sirdal area or hikes from Hunnedalen valley has loads to do, about 2 hours from Stavanger. Also some nice, shortish easy hikes just across the fjord from Stavanger you can get to in half an hour. It’s in Norwegian but you should try http://www.ut.no and search for hiking or cycling routes and cabins. Hope that helps.