The Waupaca County sheriff's office says the truck was traveling south on a road in the Township of Union around 11 a.m. Thursday when it approached a bicyclist traveling south in the northbound lane.
Authorities say the bicyclist made an abrupt right turn in the pickup's path, and the driver was unable to avoid the collision.
The sheriff's office says the bicyclist suffered massive head injuries and died at the scene. He was not wearing a helmet.
Post-Crescent Media reports the victim is a rural Manawa man. His name was not released. The sheriff's office says the truck driver was not arrested and no charges are expected.