This HD video will show you the path from Redfern to Summer Hill.
If you were to leave Sydney and head west out of town, you would likely follow the railway line from Redfern to Burwood and then head down something like the Hume Highway.
Note: There are continual improvements on this trail as part of upgrades to the stations. These all seem to be very positive. This trail is on the south side of the Iron Cove area