Cycling in Sydney Australia
interestingly a google map bike directions of Sydney to Melbourne shows this Sydney - Lithgow - Blayney - Wagga Wagga - Albury - Melbourne as the shortest route with the least vertical climbing. (which surprised me seeing as you head straight for the mountains)
Four guys from my club rode Melbourne to Sydney and went via Thredbo and Jindabyne a couple of years ago. In January I crossed paths with them on my way to Goulburn on an Audax ride somewhere near Bundanoon and they were looking a little ragged.
The climb up from Khancoban to Thredbo is "rather hard" - no water and a serious climb. Now they are in our NRS team and found it a difficult route. So maybe don't take that route.