On Thursday, a cyclist riding eastbound on a sidewalk about 3 p.m. on Harvard Street was struck by a motorist leaving an alley, Lt. Carl Povilaitis said.
The motorist fled the crash, leaving the injured cyclist, he said.
"Human decency and the law would require that if you hit somebody, you stop and make sure they are OK and render medical aid and make sure they got help," Povilaitis said. "It's unfortunate that some people just chose not to do that, and they'd rather just leave an injured person … there to fend for themselves."
Police worked into the night following up on witness accounts, which eventually led them to 24-year-old Akop Arshamian at a Sun Valley address, where he was arrested on suspicion of felony hit-and-run, police said.
Arshamian was released Friday after posting bail, according to the Los Angeles County Sheriff's Department.
The two crashes come as the city tries to make more accommodations for bicyclists, such as adding bike lanes. It has been working with the Los Angeles County Bicycle Coalition to develop a master plan.
An online survey for pedestrians and cyclists for improving the safety of neighborhood road conditions was recently posted. It can be viewed at http://tiny.cc/34btj.
"I think the survey will give us a clearer perspective of what the conditions are out there," Colin Bogart, a liaison with the nonprofit Los Angeles County Bicycle Coalition who is working with city officials.