The man had the accident while riding in Schlappintal at Klosters, in the canton of Graubünden. He suffered such severe head injuries as a result of a fall that he died at the scene of the accident, according to Swiss police reports.
The biker was with a group of other cyclists on a dirt road heading from Schlappintal down towards Klosters. On a steep paved stretch near Cünwald he lost control of his bike, and fell heavily onto the road, hitting his head.
Police from Graubünden said the man was wearing a helmet, but were unable to say which part of Austria he came from.
With the growth of mountain biking as a sport in Austria, hospital admissions for bike-related serious injuries have reached a high of 6,500 people per year.
Swiss hospitals have also been kept busy by a series of mountain biking accidents.