The incident happened on Littlehampton Road, Goring, on a roundabout around 6.15pm on Saturday, February 26 2022.
The roundabout that joins Littlehampton Road with Yeoman Road was closed while emergency services attended the scene.
The cyclist, a 79-year-old man, suffered serious injuries and was taken to hospital, where he remains in a stable condition.
Anyone with information or dashcam footage which could help officers with their investigation is asked to contact Sussex Police on collision.appeal@sussex.police.uk or call 101 quoting serial number 1026 of 26/02/2022.