Euan Paul, 21, said he couldn’t believe his eyes when he spotted the hapless man in the middle of M8 where drivers were forced to swerve to avoid hitting him.
The security engineer was in the car with his colleague when they drove across the Kingston Bridge in Glasgow which is one of the busiest bridges in Europe.
He said the cyclist was not wearing safety gear and reckons he might have taken a “wrong turn” before ending up in the middle of the carriageway.
Euan managed to film the cyclist from the passenger seat before sharing the footage on social media on Tuesday.
The 21-year-old said: “My initial reaction was shock, but the situation got funnier the longer it went on.
“We believe he may have taken a wrong turn on to the motorway at Charing Cross. He looked fearful and in tears.
“He didn’t have safety gear.”
Euan said that fellow motorists seemed less impressed with the shocking feat.