The 43-year-old was found seriously injured on a forest path between Osterode and Herzberg by an off-duty policeman also biking along the path, a police spokesman said.
The spokesman said the man was not in a life-threatening condition and was able to speak after his ordeal, but gave no details as to his injuries. He was taken by rescue helicopter to a clinic in the nearby town of Göttingen.
The man left his house on Tuesday to take a two-hour bike ride, and was reported missing by his wife when he did not return in the evening. According to the police statement, the cyclist hit a pot-hole on a decline and fell ten metres down a steep slope next to the path. He was invisible from the path and could not make himself heard, the report said.
Police, fire services and local residents spent days looking for the man, but could not find him despite the use of helicopters, boats, horse-back patrols, and infrared cameras.
A 52-year-old policeman then discovered a pair of sunglasses on the path, and, aware of the search operation taking place nearby, climbed down the incline and found the man.