The 59-year-old rider from Los Altos had been traveling on southbound Highway 101 north of University Avenue at about 7:45 p.m. when, for reasons unknown, he lost control of the motorcycle, the CHP said.
A green 2000 Toyota Corolla, which was driven by a 32-year-old Hayward man and was traveling in the same direction, struck the bike after it went down, the CHP said.
Menlo Park Fire personnel and American Medical Response paramedics responded to the scene and transported the rider to Stanford University Medical Center, where he was pronounced dead at 8:30 p.m.
No arrests were made.
The collision remains under investigation, and it was unknown as of this morning whether drugs or alcohol were a factor in the collision, the CHP said.
Anyone who may have witnessed the collision is asked to contact CHP Officer A. Galindo at (650) 369-6261.