Nails left on Adelaide road

Nail and drawing pins have been left on an Adelaide Hills road, with police saying the prank could have put lives at risk.

There have been three incidents over the past month where nails or drawing pins were left on Norton Summit Road, a popular spot for cyclists and motorcyclists.

"The reality is this disturbing behaviour could easily lead to riders being seriously injured or even killed," Inspector Gus Sickerdick said on Thursday.