One handy little trail to know in Sydney is the Liverpool to Glenfield path that runs alongside the railway line. It is at the end of the Liverpool Railtrail.
Its a bit messy in Liverpool but once you head down the hill and under the M5 bridge, it is just a good trail with river views. The highlight of the trip is the Casula Powerhouse which has art displays and good cafe where you can sit next to your bikes. After the Powerhouse, cross the railway line using the train lifts and bridge and then ride on the west side all the way to Glenfield. There are always bell birds ringing and finches jumping.
The same path will help you get to the M7 Cycleway
What is important about Glenfield is that the trains into the city are very fast as it goes express after Revesby all the way to Mascot.
The trail is here on the Sydney Map >>