Start from either the Lake Crackenback Resort (register at their office first) or park in the Ski Tube Carpark next to Bullocks Drv (use the Rutledges Hut Rd Address suppled for Google) and ride down Bullocks Drv to find the trails. From their you can head east for a technically difficult route at times, or head east and towards Thredbo for a mostly flowing ride (slightly uphill in elevation) which provides a fast run back. Nice ride along the Thredbo River with views of snow capped mountains in season.
The Lake Crackenback Resort also has few short trails around the resort itself.
Best ridden in Autumn, Summer or Spring.
Rolling Ground Map of Lake Crackenback Resort - http://www.rollingground.com.au/trails/lake-crackenback/
Rolling Ground Map of Thredbo River Trail - http://www.rollingground.com.au/trails/thredbo-valley/
Rolling Ground map of Thredbo Diggings Trails - http://www.snowymountains.com.au/tsmcraft/resources/uploads/muzzlewood_diggings_mtb_trail_map_final.pdf