The gruelling Ironman UK competition will pass through Leyland for the first time this year.
New for 2014, the 112 mile cycle route will go along Dawson Lane and then down to Runshaw Lane in Euxton via Langdale Road in Leyland.
In previous years, the bike route has taken place down Euxton Lane rather than the Langdale Road area.
This year’s event, which will be held on Sunday, July 20, will also use a longer stretch of the A6 Preston Road around Whittle-le-Woods and Clayton-le-Woods.
The new route means that the effected roads will be closed from 7am until 3.30pm on the day.
A spokesman for Ironman UK said: “Through the process of applying for a route for Ironman, we consider many alternatives in order to minimise the impact that the event will have on the local residents and businesses, although some impact is inevitable.
“Once a route has been approved by the council and police, we then work to inform the public so that we can address concerns and assist with information.”
Ironman UK is being hosted by Bolton and Lancashire.
The course comprises a 2.4 mile swim in Pennington Flash, Leigh; a 112 mile cycle ride into Lancashire and a 26.2 mile run beginning from the Reebok Stadium into Bolton town centre.
There are 50 qualifying slots for the Ironman World Championship in Hawaii in October.