Hundreds of riders taking part in a charity bike race between Edinburgh and Glasgow suffered punctures in what is believed to be an attempt to sabotage the event.
Police confirmed they are investigating incidents where bikes’ tyres were punctured during the Pedal Scotland event.
Officers in Clackmannanshire said they had launched an inquiry after metal tacks were found in the Whitecross area just after 1pm on Sunday.
They said they had also been made aware of a similar incident in and around Linlithgow.
Some competitors said there were so many punctures, repair teams could not “keep up”.
There had been complaints from residents along the route that restrictions placed upon their movement amounted to being “prisoners” in their own home.
Last week, competitors in a cycle race in the Scottish Borders claim they were attacked by farmers with sticks angry that road closures to accommodate the Tour O The Borders event disrupted their work.
Pedal Scotland now attracts 7,000 cyclists, who set off from Glasgow Green on routes that offer varying levels of difficulty.
On Sunday, they included transport minister Humza Yousaf, who waved off competitors from the starting line.
Cyclists took to social media to vent their anger at the weekend disruption.
Shona Mitchell posted a picture on Twitter, her front tyre studded by a tack.
She wrote:”Fun spoiled. Hundreds of us with flat tyres, thanks to sabotage with tacks.”
Gavin Yates replied: “Some people are really miserable sods. Hope you got Sarah to fix the puncture for you!”
One, called ‘Buttons and Robin’ wrote: “My ride was cut short due to a tack. Some riders had two or three in their tyres.
“Mechanics (heroes) couldn’t keep up. Was a damn shame not to ride those last 10 miles.”
Tony Hutchison added: “Heard that, too. Unbelievable, especially when there’s lots of kids taking part. Morons.”
A Police Scotland spokeswoman said: “Police Scotland is investigating following a report of metal tacks on the road in Whitecross during a Pedal for Scotland event.
“A number of bikes were damaged, however no cyclists were injured. There were also reports of tacks being placed on the road in and around Linlithgow.”
A Cycling Scotland spokesperson said: “Nearly 8,000 people had a fantastic time cycling with Pedal for Scotland. Friends, families and colleagues were raising money for charities close to their hearts and there was enthusiastic support from spectators in most towns and villages along the route. We regret that the action of an idiotic individual or group of people has caused problems for event participants and risked serious injury to people.”