A Twitter user captured the moment an "aggressive and off-his-nut" man was inches from being hit by a train.
The cyclist was caught on camera attempting to push his way through the barrier at a rail crossing in North Sheen just before a train passes through.
Warning - the video below contains explicit language.
Responding to onlookers who urged him not to push through, the cyclist shouted "I don't f***ing care mate" and walked up to the railway line.
Seconds later, a train beeps at him at him and drives past him at high speed, causing the cyclist to step back and gesticulate angrily.
When asked why he didn't try to stop him, the cameraman responded on Twitter saying: "The guy was very aggressive and off his nut. Would you try and stop him?"
The British Transport Police have been made aware of the video and are investigating the incident.