One of Sydney’s great rides is the Prospect Reservoir ride that starts at Guildford and ends at Canley Vale (with and optional ride back to Guildford). It clocks in around the 30km mark.
If you want to do something different, try turning right a kilometre after the Boothtown Aquaduct and heading into Pemulwuy. The cycleways around the suburbs are quite good, there is a lake or two to see and then you head to Prospect Reservoir where you get a super photo opportunity that I missed on my first 4 runs around to Canley Vale
The photos show the ride starting near Guildford with the last three showing an optional ride down the far less used Prospect Creek Cycleway to Fairfield. Click on pictures to see full size.