In summer the Cardrona Skifield converts to the Cardrona Bike Park. All the trails are accessed by ski lift and a ticket is required to ride in the park although there is one uphill track (Oxygen Thief). The setting is high up in the foothills of the Southern Alps with stunning views and a formidable on-top-of-the-world ambiance. There is a wide variety of trails from a kids area to world cup level downhill trails. You'll find cross-country style tracks as well as the downhill ones.
In peak season lifts operate daily from 10am to 4pm except on Fridays when they operate till 8pm. Later in the season they only operate on Friday, Saturday and Sunday. For specific dates check their website: www.cardrona.com.
You can catch a shuttle with bike trailer from Queenstown or from the Cardrona Valley Road turnoff. Costs and timetables are on the website: www.cardrona.com
You'll find all the facilities you need up at the resort including accommodation, food, bike hire, bike school and so on.
A good trail to start on is the intermediate Arcadia which drops 400 vertical metres over 2.4 km - you'll be smiling all the way!