Police were called by a member of the public yesterday (July 31) at 5am to report that a cyclist had been found on the ground in South Street junction with Anson Street, Sheffield
Emergency services attended and the cyclist, a man in his 20s, was taken to Hallamshire Hospital, where he remains in critical condition.
Officers are now appealing for anyone with information to come forward.
Acting Sergeant Martyn Micklethwaite, the officer leading the investigation, said: "This cyclist has suffered life-threatening injuries and our officers are currently doing everything they can do investigate the cause of the incident.
"The cyclist was found in a busy part of Sheffield so I would urge anyone who witnessed the incident, or who has dashcam or CCTV footage, to come forward."
Anyone with information is asked to call 101, quoting incident number 194 of 31 July, or anonymously through Crimestoppers by calling 0800 555111.