The Jefferson County Sheriff's Office was investigating after the tires on eight bicycles were flattened by tack strewn along a popular bike route.
Deputies were called to Deer Creek Canyon Road near South Valley Parkway around 6:30 a.m. Sunday, according to Mark Techmeyer, spokesman for the Jefferson County Sheriff's Office.
There has been a history of tension between drivers and bicyclists in Deer Creek Canyon, which is southwest of Ken Caryl.
In 2011, the Sheriff's Office was investigating reports of utility blades and tacks found along the trail.
The sheriff's office said those foreign objects were purposely being placed on trails and roads popular with bicyclists.
Bike Jeffco, a bicycling advocacy group, counted how many cyclists and motorist were using the canyon in June of 2013. The survey showed that in a 12-hour period 881 bicycles passing through the intersection commonly referred to as Philipsburg.