Wire strung across popular bike path causes two "serious" crashes ahead of Tour Down Under, days after police chief urged "extra level of vigilance" on roads due to "abundance of cyclists" around pro races

South Australia Police have raised the alarm to cyclists in Adelaide, with many professional riders and fans currently in the city for the upcoming Tour Down Under, after two "serious" incidents saw a wire strung across a popular bike path cause crashes.

On Friday 10 January, a group of three riders were brought down by the wire trap when they hit it at 35km/h at around 6.20am. SA Police reported the wire had been removed from a fence and then tied to a tree across the path, causing minor injuries and "severe damage" to the victims' bikes.

A second incident then occurred at 6.45am on Monday 13 January, a female cyclist again hitting a wire that had been strung across the path and tied to a tree. The woman's bike suffered "extensive damage" although the police confirmed she escaped injury.

Both incidents happened on the same stretch of bike path that runs next to the Southern Expressway at Noarlunga Downs, a suburb of Adelaide. The off-road route is a paved, two-way cycleway popular with local riders for its traffic-free access.

The attacks come at a time when Adelaide is playing host to hundreds of professional riders and fans visiting the city and South Australia state for the upcoming editions of the Santos Tour Down Under. 

"Southern District police are following a line of investigation but have urged all cyclists to be aware of the potential danger and be alert when using bike paths along the Southern Expressway," a statement released today said.

"Anyone with any information that may assist with the investigation is urged to contact Crime Stoppers.  You can anonymously provide information to Crime Stoppers online at https://crimestopperssa.com.au or free call 1800 333 000."

Last week, SA Police Commissioner Grant Stevens urged road users to be "extra vigilant" during January, as the WorldTour races will bring an "abundance of cyclists on the road".

His comments came last week after a motorist was charged with causing death by dangerous driving in relation to the death of a motorcyclist.

Stevens urged all road users to "use the roads as safely as possible" and said "there is an extra level of vigilance required from people who we consider to be vulnerable road users because the risks are that much greater".

"Enjoy South Australia. Enjoy what it has to offer, but do so safely," he said, asking all road users to be patient while there is an "abundance of cyclists on the road".

"The Santos Tour Down Under will attract more cyclists across the city and South Australian regions. If ever there was a time to be very mindful of sharing the road, it's now," he said. "All road users must be vigilant for cyclists. Drivers are used to looking for other larger vehicles like cars and trucks, but cyclists are smaller, quick and can be more difficult to see. Be extra vigilant especially around intersections and when executing left hand turns.

"Spectators sitting kerbside to watch the race should keep road edges clear to leave space for cyclists to overtake and for support vehicles to use. Spectators driving or starting cars near flammable bush or grass should be aware of the hazard this brings in starting a fire.

"For people travelling in the area, the Tour will feature rolling road closures that are outlined on the Santos Tour Down Under website. Plan ahead and leave time for possible delays in and around these areas."

SA Police undertook a 'Safe Cycling' operation during last year's race, an action which ABC reported saw 440 expiations and cautions issued during January, 426 of those issued to cyclists. Bicycle riders in the state are required to wear a helmet and the SA government website states that riders can ride two abreast, but "you must both be within the bicycle lane".