Officers are appealing for information and dashcam footage from members of the public following an incident involving two men from Chester.
Between 12.15pm and 12.30pm on Tuesday 1 October an 86-year-old riding a bicycle collided with a 58-year-old out walking his dog.
The older man is believed to have sustained a serious injury as a result of the incident that occurred near an Aldi store on Tarvin Road in Chester.
He was taken to hospital in an ambulance.
The younger man, who spoke to officers at the scene, is not believed to have been injured.
Officers are investigating the incident and want to speak to anyone who was in the area and saw what happened.
They also want to hear from any motorists who believe they may have captured relevant footage on their dashcams.
Anyone with information or dashcam footage that may help the investigation is asked to call Cheshire Constabulary on 101, quoting IML 817687, or give the details via https://www.cheshire.police.uk/ro/report.