Police are searching for someone “actively harming the public” after wires were strung up across a popular bike path in Adelaide, tripping and injuring unassuming cyclists.

Obstacles were found on the path along the Southern Expressway at Hackham West.

Three men riding their bicycles at 35km/h were struck and sent flying about 6.20am on Friday.

“[They were] minding their own business, enjoying their Friday morning ride and they’ve been struck down by a stretch of wire that’s been placed across from a fence line on the western side of the expressway and tied to a tree opposite at about a metre height,” Detective Chief Inspector Mark McEachern told reporters.

“So the most dangerous height you can possibly get for a cyclist going down the bike track.”

McEachern said two of the three men suffered minor injuries, including nasty bruises.

Their bicycles, which were in excess of $10,000, were severely damaged.

Then about 6.45am yesterday, a woman riding the path between Honeypot Road and Beach Road struck a wire that had been strung across the path in a similar fashion.

“Her handlebar collided with the wire, ripped those off, so it caused damage to her bike and somehow she wasn’t injured,” McEachern said.

The woman noticed a man walking north on the bikeway. McEachern urged him to come forward to assist in their investigation.

McEachern said the second incident revealed the strung wires were “far more sinister” than “opportunistic”.

“There is somebody actively harming the public by stupidly pulling this wire across the bikeway to knock cyclists off,” he said.

“Why you would do that, who knows. Stupidity and cowardness come to mind.

“It’s obviously very serious offending. It’s offending that accounts to acts to endanger life which carries a maximum of 18 years imprisonment.” 

Police are currently following a line of investigation. They will be maintaining a presence in the area and throwing resources at finding out who is responsible.

In the meantime, cyclists are urged to be aware of the potential danger.