Good thread. This has been my fave so far:
Route Name: Royal National Park Loop
From/To: Waratah Park Reserve, Loftus
Nearest Station: Loftus (but Sutherland is better - more trains)
Duration: 3 hrs?
Route Map See here: http://nobmob.com/node/3490
From Waratah Park, take the highway south to Loftus Oval. There’s a bit of singletrack heading east from the carpark, some sandy firetrail, then a steep section down to Temptation Creek with a rocky climb out again (may struggle on cx). More singletrack up to the National Parks centre.
Take the bitumen down the hill to Audley Weir, then follow Lady Carrington Drive for 10k of very nice firetrail. McKell Ave takes you back up to Waterfall, then the highway north to Heathcote. (Alternative routes are possible through Heathcote National Park if you can find them.)
Cross the train line at Heathcote, and take Bottle Forest Rd straight into the forest (sweet sandy singletrack). There are options for extra side trails around Engadine and some rough rocky sections.
Follow the fire trail to Farnell Ave, cross it, then follow the singletrack back to Loftus Oval. This bit is great. Back at Loftus Oval there’s a trail through the bush that will take you back to the highway crossing.