It certainly takes an incredible amount of fitness and endurance to do an event like this.
I would be more than happy just to do 100km of the ride alone!.
On a side note, has anyone been to The Bike Shed in Mortdale NSW before? Can they recommend them?
Just looked online at some of their bikes and are amazed at the prices they are selling some of their Focus bikes for. Yes, I know you wont get fit or advice right like an LBS would offer, but these prices are exceptionally tempting.
http://tbsm.com.au/bikes/road/road-race-training