Officers are appealing for witnesses and dashcam footage following a collision in Christleton.
The incident took place on Whitchurch Road at around 3.40pm on Thursday 10 December and involved a cyclist and a lorry.
The cyclist, a 14-year-old boy, was taken to hospital by air ambulance.
His condition is described as serious.
The driver of the lorry stopped at the scene and is assisting police with their enquiries.
Officers want to speak to any drivers who believe that they may have captured any footage to come forward.
Anyone with information or dashcam footage that may help the investigation is asked to call Cheshire Constabulary on 101 quoting IML 870470 or report it via https://www.cheshire.police.uk/ro/report
Continued parking chaos at Wrexham Maelor Hospital
Residents invited to have their say on draft Transformation Strategy
Family of "beautiful" son who died following Chester collision pay tribute
Chester and Wirral Football League - Weekend Round Up
Back to the Future event to be held at Picturehouse Cinema
Children and families in Cheshire to benefit from new Child Focused Courts approach
Residents invited to help shape the future of Whitby Park
WREXHAM COMMUNITY THEATRE COMPANY RETURNS WITH BRAND NEW SHOW IN TIME FOR HALLOWEEN
Blues Match Report: Lower Breck 1 - 2 Chester
Appeal for information following serious collision in Chester
Parents warn of “catastrophic tragedy” as school transport cuts leave 11-year-olds stranded on the A41
Live Facial Recognition technology to be deployed in Chester this weekend
Road to reopen as part of town centre
£1 bus travel launched for young people across Cheshire West and Chester
Peak Cluster carbon capture and pipeline project in Cheshire West and Chester
Officers out in force in Blacon for Operation Decisive
Neighbourhood Plan and Neighbourhood Development Order finalised for Blacon