The Conservation Authority says mountain-biking will be allowed on the Heaphy Track in the South Island next winter season as part of a three-year trial.
The track was closed to mountain-bikes when the Kahurangi National Park in was gazetted in 1996.
Since then, mountain-bikers have campaigned to have the 82km track reopened to cyclists.
The trial will run between 1 May and 30 September each year on the Heaphy Track.
Two other trails, the Flora Saddle to Barron Flat and Kill Devil tracks, will be open year-round until the end of 2013.
The Department of Conservation will monitor the social and environmental impacts of the mountain-biking to determine whether it will continue after the trial period.
Mountain Bike New Zealand has been campaigning for the move and believes bikers and trampers will co-exist well on the track.
It says thousands of mountain bikers will see the Heaphy as a must-do winter trip.