Lived there for 18 months.
Lots of darkside riding – there’s a loop down the coast and round the river through the city (about 50km) with at least one bunch ride a day and loads of bunches on sat. (they ride early though – 6am meet in summer).
MTB wise some good riding in the hills which are east of the city. That is a good 40 minute drive potentially depending on where you live (lots of brits live down by the coast).
I know a couple of people who are national level aussie riders who both live in Perth so it is reasonable…
Try contacting Jo and Tim at kalamunda cycles for more advice.
I’d take roadbike and mtb if you have both.