
Police said Stephen B Mark, 42, died at the scene due to head injuries and a broken neck.
They said the accident occurred at 7.30am on outbound Rojana Road in Phra Nakhon Ayutthaya district’s Tambon Klong Suan Plu.
The motorcyclist, identified as Mongkolrirk Klunsaisook, 28, claimed the cyclist fell against him and tumbled over.
Police suspect the two men somehow grazed one another, flipping the bicycle.
They said Mark worked in Ayutthaya’s Hitech Industrial Zone and often cycled around the province. His wife in Phuket had been informed, they said.