Sussex Police said the 50-year-old cyclist, from Shoreham, was cycling along Kingston Lane at around 6pm yesterday (May 26) when he was involved in a collision with a Land Rover Discovery.
He suffered what police described as 'serious injuries' and was taken by air ambulance to the Royal Sussex County Hospital for treatment.
The driver of the Land Rover, an 80-year-old man from Steyning, was uninjured. The road was reopened shortly after 9pm.
Anyone who witnessed the collision is asked to email c[email protected] or call 101 quoting Operation Elmsted