Private Trail. You need to pay for riding it before you get there but it is well worth it. You can do this online. http://www.welcomerock.co.nz/
Starts and ends at the old ski hut. 27Km loop, hand built trail, many historic elements and features, cool huts along the way, the famous Welcome Rock with great views. 21Km is single track, cross country with a fast flowing downhill, finish loop with a few Kms on gravel road.