Melbourne's got a bunch of trails for bikes and pedestrians that traverse the city. Although they're frequently narrow, hilly and almost never take the direct route from anywhere to anywhere, they frequently go through some nice bushland and are technically "off road". With some judicious navigation, it should be possible to connect a bunch of them together and get all the way out to Warburton... if you're willing to ride that far.

Because I still need to work on my bike, but I need some practice for Around The Bay, I'm doing this on an e-bike I've hired - a Tern GSD cargo bike. Which will totally be fun...

Apologies for the sometimes chaotic camera work here. I had a GoPro mounted on my helmet, and as you'll know, you tend to need to look in about 6 directions at once while riding. Never realised quite how much I look up and down, either...