Mending her front tyre, which had three thumb tacks embedded in it, took her 15 minutes. She said she finished third in the women's 45-49 category, some nine minutes behind the eventual winner.

'I'm so angry, I don't think I can sleep for the next three days,' said the Ernst & Young (Japanese business services) coordinator.

'This has ruined my race and my day.'

At least four bikes were nailed, The Straits Times understands. Elvia Suryadi, 32, had to wheel her bike for 80 minutes barefoot, as she did not have a spare tyre with her.

'I wanted to cry each step of the way,' said the lecturer, who had to take off her cycling shoes to walk from the Singapore Flyer to East Coast Park.

Race organiser Hi-Tri said it cleared the thumb tacks, scattered on the road near the Keppel Flyover, immediately when told about them.

But it is uncertain if the sabotage was confined to just one spot, as Kume said her tyre was punctured just before Fort Road.

Read the full story in today's edition of The Straits Times.