Melbourne is a very bike-friendly city with lots of good riding options.
If you feel like some longer rides, Strava has a list of seven iconic Melbourne rides.
There are 10 bike racks (for 20 bikes) in the centre of MCEC, between the exhibition bit and the conference bit, in the "crook of the elbow" of the buildings. They are partly undercover.
There are also 6 bike racks (for 12 bikes) near the bridge over the river on Spencer St, but this is much further from our rooms and much more exposed to passing pedestrian traffic.