Officers were called at 7.09pm on Sunday, 5 December, to reports of a road traffic collision involving a car and a motorcycle in Burnt Oak Broadway, Edgware.
The rider of the motorcycle – a 44-year-old man – was taken to hospital. His condition is critical and the man’s family have been informed.
The driver of the car – a silver Nissan Micra – stopped at the scene. There has been no arrest.
Anyone who witnessed the incident or has dashcam footage that may assist police is asked to call officers at Alperton on 020 8246 9820.