Flora Duffy's start to her Olympic season was riddled with more misfortune with the triathlete falling off her bike during the Under-23 World Championships in Canada on Sunday.

The temperature was so cold in Vancouver that Duffy also lost crucial time while attempting to fasten the strap of her helmet, undermining the healthy position she had gained after a strong swim.

Charlie Duffy admitted his daughter was still below her best, but said bad luck was a major factor in her disappointing 17th-place finish.

"The worst thing was Flora came off her bike during lap seven," he said yesterday.

"That's why she had the slowest time on the bike. She had a strong swim but the temperature was freezing and Flora struggled to fasten her helmet.

"The front three went without her and the next group didn't really work with her and she had to ride by herself for a long time.

"By the time she got to the run she was pretty beat up. She's not at her best yet but she's certainly trying her best."

Duffy failed to finish her opening race of the season in South Africa last month because of mechanical difficulties with her bike.

She's already qualified for the Olympic Games in China which begin on August 8.