The fastest way to the top of Thredbo is by chairlift. The fastest way down is by mountainbike. From the top of the chairlifts are marked mountainbike tracks, downhill tracks if you will. You could ride any mountainbike down but a downhill (DH) specific bike is the easiest and the quickest. The main DH trail begins on the access gravel road and after an introduction to water-bars it sweeps into single track. This track is not for the faint hearted, even the B lines required technical abilities. Marked with boulders, tree roots and tight burms this gravity fed track goes only one way, that’s down. There is no need for a chain, as you can quite easily coast the entire way. If you want to go faster, remove your vice like grip of the brake levers, peddle a bit and do a sub 10min run.
Don't forget kids, to wear amour. After a couple of runs I had a grasp of the run, well that's what I thought. Then I found myself flying across the rocks. With claret oozing and a bit of gravel rash I thanked the full face helmet for saving my head, body amour and knee/shin guards for saving most of my skin. At pace there were some good rhythms you could get into over the boulders and also in the switchbacks.
Give a gravity run a go some time, it is real fun, just do it safely.