The car-hauling trailer was parked legally near 85 River St., south of Randall, when Codly Allen Reynolds crashed into the trailer's back corner.
"He was not wearing a helmet, and suffered some massive head injury at the time," said Sgt. Kevin Allman. "It was raining at the time and dark."
Investigators are working to determine the speed of the mo-ped at the time of the accident. "Under state law, mo-peds cannot go any faster than 30 mph, so whether or not it was faster, we don't know," said Allman.
The Coopersville-area victim's identity has not been released.