A competition, thought to be the world's first urban downhill race to take place at night, is being held in Edinburgh at the weekend.
More than 250 bike riders are due to participate in the city race
More than 250 mountain bikers will race against the clock through the streets and down the city's steep stairs.
Thousands of spectators are expected to travel to the capital for the event, which has a £3,000 prize pot for the professional riders.
The event is being held on Saturday night.
To keep up suspense, the organisers have kept the official course "top secret".
Ian Williams, events manager for Fat Face, said: "The Urban Downhill at Night will bring all the elements of the off-road sport to the centre of one of the most iconic cities of the UK.
"It has been a pleasure working with the very proactive team at the Edinburgh Council to pull this off."
Practice runs will begin at 1000 BST on Saturday followed by seeding runs at 1500 BST and the finals taking place between 1900 BST and 2130 BST.