Officers are appealing for witnesses following a serious collision close to Crystal Palace Railway Station.
Police were called by the London Ambulance Service shortly after 08:00hrs on Sunday, 10 June to reports of a collision involving a car and cyclist on Anerley Road at the junction with Crystal Palace Station Road.
Officers and London's Air Ambulance attended.
The 45-year-old male cyclist was taken to a south London hospital where he remains in a critical condition.
The car stopped at the scene and the driver was spoken to by police who is assisting them with their enquiries"
Detectives from the Roads and Transport Policing Command are investigating.
They would like to speak with anyone who saw the collision occur, or who may have dash cam footage.
Anyone with information is asked to contact the Serious Collision Investigation Unit on 020 8285 1574.