The victim's lifeless body was discovered at 3am on Sunday at the side of a road between Henschiken and Dintikon in the northern part of Switzerland, west of Zurich.
The man, who was cycling without a helmet and without lights, was hit by a car “with great force” from behind and was thrown several metres, police spokesman Bernhard Graser told 20 MInuten newspaper.
It is not clear when the accident occurred but the victim was on his way to work when the accident occurred, Graser said.
The motorist involved drove on without reporting the collision.
The victim, from the canton of Thurgau, was an apprentice who worked part-time for a milk transport company, 20 Minuten reported.
At the time of the accident he was on his way to pick up a tanker truck, and was supposed to pick up milk from 40 dairy farmers in the region, the newspaper said.
The head of the milk transport company said the victim usually wore clothes with fluoresecent stripes.
Later on Sunday, the 28-year-old driver of a damaged black Alfa Romeo car, believed to be involved in the accident, turned himself into police.
The man was to be questioned by investigators to ascertain further information about what happened.
UPDATE: The local prosecutor's office reported on Monday that the driver said he thought he had hit an animal.
An investigation into homicide caused by negligence is under way.