Thousands of bus passengers are riding for free today as drivers protest against government plans to privatise services in the inner west.

Drivers have declared it’s a "fare-free day" and have switched off their Opal Card machines in 12 Sydney depots currently managed by the government-owned State Transit.

These areas are in the inner west, east and north west suburbs to Epping, and across the Lower North Shore and to the Northern Beaches. The protest follows 1200 drivers walking off the job last month.