Years ago there used to be so much good trail in the Grampians and with some parts of it quite life threatening. Well on CroMo rigid sharp steering bikes of that era it was. Shirtz, if you have a few hours to kill and want to smash some calories, then this one is a nice ride we did a few years ago - but no single trail.
This is a bit of a tough one physically but it takes you through some of the best in the area. This ride takes you up and over Mt Victory below. The sort of place where it's a bit of a bonus to ride on wider 4WD tracks to give you a chance to take in the scenery.
There are a couple of hidden gems too. This waterfall completely hidden from the track that was flowing in the height of summer. You must keep your ears alert at around the 19.4km mark and follow your ears into the bush. My wife and I had a welcome rest under that clear cool water.
There is a sensational stand of grass trees about 600m up Zumsteins track from Mt Victory Road. These grass trees were taller than us and whilst there are plenty fo them scattered around the park, this is probably the best you'll see in Victoria.
If you're into a bit of mountain climbing as well, Wallaby Rocks has some nice bouldering opportunities. Nothing difficult but lots of interesting cracks and fissures with stable granite that doesn't exfoliate when you least expect it to.
Nearly 40km from memory but with nearly a km of total ascent. Some parts were very rough and some of the down hills were pretty rough so little chance to catch your breath. Mind you the heat can be pretty harsh. Not the most fantastic riding I've done but still good fun.
I have uploaded a KML file for Google Earth or copy/paste the link into Google Maps:
http://www.isi-carriers.com/temp/kml/Grampians.kml
Hope this helps.