Detectives are appealing for witnesses and anyone with dash cam footage to come forward following a collision in Westminster.
Officers attended along with paramedics from the London Ambulance Service (LAS).
The female cyclist, aged in her 20s, was found seriously injured. She was treated at the scene before being taken to hospital, where she remains in a serious but stable condition.
Two men, both aged in their 30s, were arrested on suspicion of causing serious injury by dangerous driving. They were taken into custody and subsequently released under investigation.
Any witnesses or anyone with any information is asked to call the Serious Collision Investigation Unit on 020 8543 5157 or police on 101, quoting CAD 7117/17OCT.