The collision, which occurred at 8.30pm on Thursday 24 December 2020 near to Spitfire Way, involved a blue Harley Davidson motorbike.
The rider, a man in his 20s, suffered serious injuries and was taken to a London hospital for treatment.
Officers from the Serious Collision Investigation Unit are urging any witnesses to come forward with information. They believe a car was parked nearby in a layby at the time of the incident and the driver may have witnessed the collision and could have information to assist with their enquiries.
Witnesses are asked to phone the dedicated SCIU witness appeal line on 01622 798538 quoting reference number HW/SW/115/20. Alternatively email [email protected]