On Saturday morning, bikers discovered the “Canada Trail" in Callendar Park, Falkirk, was laden with branches and fence-posts lashed together with rusted razor wire.
Photos from the route, which is classified as “green” and suitable for beginner riders, show it blocked at key sections by the obstacles.
Warning others in a post on social media, one furious rider wrote: “A word of caution to anyone riding the green "Canada Trail" from the Greenrig carpark.
“Someone is sabotaging and blockading the trail with branches, fence-posts and barbed wire.
“Yes, BARBED WIRE. Absolutely ****ing ridiculous.”
They said they feared the blockade was designed to injure riders, since it had been erected at the bottom of a “small, steep section” of the trail.
“I'm aware this has been happening frequently over the past few months with others posting photos in local biking groups,” they wrote.
“I ask that everyone else who sees similar please does the same - might seem minor, but the right thing to do is catalogue this.
They added: “Hopefully it won't get out of hand.”
On Saturday, Police Scotland confirmed that it has launched an investigation into the incident but did not give details on lines of inquiry.
A spokesperson for the force said: “We received a report around 3pm on Saturday, 1 May, relating to items being placed across bike trails at Callendar Park, Falkirk.
They added: “Enquiries are at an early stage.”