A cyclist was found unconscious in a road in Thames Ditton on Thursday.
The man, believed to be in his 40s, suffered injuries to his head after coming off his bicycle in Winters Road shortly before noon on January 9.
A South East Coast Ambulance Service spokesman said two ambulances and the air ambulance were sent to the scene and the cyclist, who regained consciousness, was taken to St George’s Hospital by road as a priority.
Surrey Police closed the road while paramedics treated the man.
Police are continuing their enquires to establish what happened leading up to the incident.
Anyone with information who has not yet spoken to officers should call Surrey Police on 101, quoting reference P14007933.