Dramatic dascham vision has captured the moment a cyclist dangerously swerves across a highway exit ramp after crossing the Sydney Harbour Bridge.

9NEWS has obtained vision of the cyclist risking his life at about 2.30am this morning, prompting one concerned motorist to pull over and have a word with him.

The footage starts with the man riding across the harbour bridge, where bicycles are strictly not allowed.

WATCH the cyclist put his life on the line in the video above

The cyclist made the dangerous to decision to ride over the Sydney Harbour Bridge.

The man recording the cyclist managed to stop and talk to him.

The man then makes his way up the Warringah Freeway, before making the snap decision to dart across the exit ramp heading toward Military Rd.

The motorist recording the footage managed to stop the cyclist during his trip.

The man darted across an exit ramp after the bridge.

"You'll get yourself killed, you're not allowed to ride here," the motorist said.