The Naseby 12-Hour Challenge is celebrating its 10th anniversary tomorrow with a 1970s theme.
Race director Craig Bates said he was encouraging riders to dress up, while the Larchview Holiday Park, where the event was based, would have a '70s makeover.
Disco balls, strobe lighting, a DJ, and a ''tunnel of love'' would complete the transformation of the camping ground.
Bates said about a quarter of the 805 entrants competing in the challenge had attended every year since its inception.
Online entries for the event had sold out 16 minutes after opening at 9pm on February 1.
The number of entries had been capped at 800 due to camping ground capacity, Bates said.
More than 2000 people were expected in Naseby over the weekend, he said.
''The pubs will be packed on Friday and Saturday night. There won't be standing room.''
Numbers of visitors during the weekend were positive for Naseby, he said.
''Anything like that helps the economy.''
Leading contenders in the race will include Matthew Lees (Dunedin) and Erin Greene (Queenstown).
Both competed in the world 24hr mountain bike championships in Australia last year.
Also entered in the race is former Olympic mountain biker Kashi Leuchs, of Dunedin.
During the event, competitors in teams, or individually, have 12 hours to complete as many laps of an 11.5km loop track through forest and land near Naseby as possible.
Bates said the route would incorporate old sections which had not been used in the race recently, and he expected each loop to take from 30 to 40 minutes.
Organised by Mountain Biking Otago, the race begins at 10am and runs until 10pm.
Competitors are expected to need lights from about 7.30pm.
- Leith Huffadine
