Well your coming to the right place. We are spoilt here, my personal fav's go something like:
1. Forrest (2.5hrs from CBD)
2. Woodend - Wombat Track (1hr from CBD)
3. Silvan - Ask at Cog bike shop (1Hr from CBD)
4. Smiths Gully - Ask bloke at general store
5. Buxton / Lake Mountain (2.5hrs from CBD)
6. Blackwood - Shhhhhh
7. You Yangs - 45mins west of CBD
8. Lysterfield - 45mins east of CBD
9. Castlemaine