The man was seen riding on the North-South motorway near Bolivar in Adelaide’s northern suburbs just before 1.30pm yesterday.
The cyclist was recorded in the middle of the motorway, before veering across two lanes of traffic, moments before another car merged into the road.
The cyclist can then be seen swerving across four lanes of traffic while cars attempt to pass him.
The road has a 110km/h speed limit leaving more than a dozen cars stuck behind the idling rider at one point.
There were some cars who tried to create a buffer for the cyclist by trying to drive in front of him.
“(It was) very dangerous, not for him, but for other people too,” witness Tarlochan Singh told 9News.
Police were called to the scene and a 57-year-old man from St Kilda was fined for riding contrary to road signs, moving into the path of a driver, and riding without a warning device.