It is believed that no other vehicles were involved when the bike crashed on Robson Avenue, near Roundwood Park, last Wednesday (December 4) at 8.15am.
The Metropolitan Police says that at the time, the rider did not appear to be seriously injured.
However, he was admitted to hospital for treatment and died days later on Sunday (December 8).
Officers are working to identify the victim and inform his next of kin.
An appeal has been launched for any witnesses or people with dashcam footage around the time of the incident to come forward.
Anyone with information is asked to either contact the serious investigation unit on 0208 246 9820, call police on 101 or message @MetCC on X quoting reference CAD3645/10Dec.
