Amazing Race host Phil Keoghan can't wait to premiere his new film Le Ride, at the Isaac Theatre Royal on Friday night.

Amazing Race host Phil Keoghan is coming home to premiere his new film at the Isaac Theatre Royal in Christchurch.

When the lights fade in the theatre on Friday night, it will be the end of a six-year journey for Keoghan that involved cycling hundreds of kilometres up mountains on an ancient bicycle, blacking out with exhaustion and getting lost in small French towns.

The journey of endurance was made to bring alive the story of a great Christchurch hero - legendary champion cyclist Harry Watson.

Iain McGregor Phil Keoghan admires the restored Isaac Theatre Royal, where his new film will premiere on Friday night.

Keoghan wanted to make sure the documentary about the cyclist's achievements, Le Ride, had its world premiere at the heart of his and Watson's home town. It is screening as part of the New Zealand International Film Festival.

"We really wanted this to be the first place."

"The significance of being in this building. I used to walk past this theatre every day when I worked down the road. I never imagined I would be back here with a film just 30 years later. My parents will be here, Harry Watson's extended family will be here, the cyclists of Christchurch will be here and people I used to work with at Television New Zealand will be here, hopefully they will enjoy the film."

Supplied Phil Keoghan and Ben Cornell take to the road on vintage bicycles for new documentary Le Ride.

"It's a great bookend to the journey of making this film. We wanted the release of the film to start here."

In 1928, Watson and three Australian cyclists competed in the Tour de France, taking on one of the toughest cycling competitions in the world. For his new film, Keoghan retraced Watson's route, using bicycles as close to Watson's heavy metal-framed 1928 originals as possible.

It was a gruelling 26-day endurance test where they cycled an average of 350 kilometres a day, sometimes climbing 6,000 metres in a single day, which is the equivalent of nearly two Mt Cook ascents.

"I will never do it again. It was ridiculous what we did."

"When it was most difficult, I was so out of it that my brain wasn't even able to register quitting. There were huge chunks of time that we don't remember."

"It was too overwhelming to think of the enormity of what we were doing."

He said it was worth it to pay tribute to an overlooked Christchurch hero.

"We have captured a piece of New Zealand history that might otherwise have been lost."