THREE former Olympic athletes will be among a record 1,400 competitors taking part in the third Challenge Henley triathlon and Henley half triathlon on Sunday.
Five-times Olympic skier Graham Bell, who lives in New Street, Henley, will be competing in the half-iron triathlon along with swimmer Steve Parry, who won a bronze medal at the 2004 Athens Olympics.
Olympic pole vaulter Nick Buckfield, the former British outdoor record holder, will be competing in his first iron-distance triathlon.
The first stage of the "ultra-triathlon" involves a 3.8km swim along the Henley Royal Regatta reach.
Competitors, who range in age from their teens to their late sixties, will then take on the new 180km cycle route which passes through Nettlebed, Rotherfield Greys and Howe Hill.
They will then run 42.2km through Henley and along the Thames towpath.
Race director Alan Rose said: "We are very excited at delivering the Challenge Henley triathlon for a third year and making sure that all competitors have an exceptional race experience.
"We are very excited about the new course, giving the athletes a new route and new challenges."
Many local residents will be taking part in both the full distance triathlon and the shorter event.
Other athletes will be travelling from as far afield as New Zealand, India, Korea and South Africa.
Professional athletes will be competing for a share of the 50,000 euros prize fund.
Stephen Bayliss, who won last year, will be aiming to defend his title but faces strong competition from Joel Jameson, who came second last year, and Tuukka Miettinen, who finished third.
Other contenders include Chris Goodfellow, who won the Forestman triathlon in June, and Tom Lowe, who will be racing in the UK for the first time.
Gina Crawford, last yearís fastest female, has decided not to compete for financial reasons but hopes to return.
Bella Bayliss, who finished second last year, and Yvette Grice, who won the inaugural race, will return.
The event is expected to raise £20,000 for the Sue Ryder hospice in Nettlebed, the raceís chosen charity for the second consecutive year. Competitors have been grouped according to their ability and their starts will be staggered.
The first wave of swimmers will begin at 6.30am from Henley Business School, swimming upstream towards Henley before turning around and returning to the start.
The fastest swimmers will begin the cycling section less than an hour later, exiting the business school and turning on to Fair Mile, as in previous years, before passing through Bix and Nettlebed.
Competitors will then cycle through Highmoor and Rotherfield Greys before turning round and returning to the Nettlebed roundabout, where they will turn left along the high street.
They will then turn left off the A4130 past Huntercombe Golf Club and through Morganís Wood before turning back along the road, passing through Huntercombe End and joining the B481 heading towards Watlington.
After cycling down Howe Hill, competitors will cycle up the road before descending back to Nettlebed, through Bix and on to Fair Mile, ready to start the second of their three laps.
Feed stations will be available at six points along the cycle route, including at Fair Mile and by the Maltsters Arms in Rotherfield Greys.
After completing the cycle section, athletes will run four laps of a course which goes from Phyllis Court Club through Remenham and Aston on to the Thames towpath and back towards Henley Bridge. The fastest entrants will finish at about 3pm while the last person is expected to cross the finish line eight hours later.
A finish area for entrantsí supporters will be set up at Phyllis Court Club and athletes will be able to cross the finish line with their children or other members of their family.
Thousands of people are expected to line the route to show their support.
Mr Rose said supporters helped the athletes to perform their best.
He said: "If the local support is anything like it was in both 2011 and 2012 all athletes will have an amazing day.
"We hope to see as many people as possible supporting the athletes on both the bike and run course."
A new road closure system will be in operation following complaints from residents in previous years that they were trapped in their homes.
A Challenge Henley spokeswoman said: "We must stress that although the cycle route is closed, this does not mean residents canít leave or return to their house.
"The new system removes the need for direct communication with the race headquarters, allowing vehicle movement to be unaffected by any communication issues.
"The course has been divided into sections and each section will have dedicated motorcycle escorts patrolling up and down these sections.
"Any vehicle wanting access or egress will need to wait at the entrance point to the closed road and a motorcycle escort will pass and escort you in or out."