The Bjelasica massif has one of the better-marked trail networks in Montenegro — the "Top Biking and Hiking Trails of Central Montenegro" mapping project tagged a few hundred kilometres of routes through here in the late 2010s. Beyond Biogradska Gora's gentle loops, you can climb any of the six 2000+ metre peaks (Crna Glava, Zekova Glava, Strmenica, Šiška) on day hikes, or string several together on a 2-3 day traverse staying at katuns.
The "Top Trails" maps are reliably stocked in Kolašin's tourist office and at the Biogradska Gora visitor centre. Look for the local guides — the Planinarski Klub Komovi in Kolašin can match you with a guide for around €40-50 a day. Many trails cross military exercise areas; pay attention to local warnings, especially east of the main ridge.