An elderly woman was struck and seriously injured by a passing electric bike before the rider fled the scene.
The woman, aged in her 80s, remains in hospital after the crash, which happened in Tuebrook, Liverpool.
The male rider fell, but then rode away along Marlborough Road, Merseyside Police said.
Officers are appealing for anyone who witnessed the 31 July incident, which happened at about 11:50 BST, to contact the force.
Police also want to hear from anyone with CCTV or dashcam footage.
Insp Stuart McIver appealed for the rider "to do the right thing and come forward".