He was a student at Eisenhower High School. Relatives said they are baffled by the crime.
"I just want to catch the people who did this to my son," said Romero's father, Michael Romero Sr. "He was a good kid. He wasn't a gang banger, he was a good kid, 17 and had his whole life ahead of him."
Michael Jr. was well known in the area. Friends say he was a good kid who tried to avoid trouble.
"Every day he would come by my house, wave to me and speak to my son. He was a really nice kid," said Bridget Hernandez, Romero's neighbor and friend.
While friends and family have nothing but kind words to say about Romero, this neighborhood has seen its share of trouble, and his murder is just the latest sign of how bad things are.
"Between Fifth and Meridian is a bad neighborhood. I guess they do a lot of drugs, and they sell," said Lisa Williams of San Bernardino.
For Romero's family, it's not just about finding justice. It's about finding answers to why someone would want to murder a 17-year-old riding his bike.
Anyone with information is urged to call the San Bernardino Police Department's crime tip hotline at (909) 384-5656.