Mountain bikers could face anything from mechanical problems to hallucinations when they tackle the World Solo 24 Hour Mountain Bike Championships in Rotorua.
The annual event is being held in New Zealand for the first time this weekend and is one of the feature events at the Rotorua Bike Festival.
The format of the race will see riders complete as many laps of a 17.3km circuit in the Whaka Forest as possible over 24 hours.
Organiser Tim Farmer, from Rotorua's Nduro Events, said many of the competitors will ride for 24 hours straight without sleeping, and will face plenty of challenges along the way.
"They could face equipment failures, body failures, nutritional issues, the weather can play a part, there is so many variables," he said.