A bike-riding mugger left a woman with head injuries Friday, after he grabbed her hair and dragged her during the crime.

Police say that the victim, a 30-year-old woman, was walking on the first block of New Montgomery Street (which is between Howard and Mission Streets) when the attack occurred.

At 11:05 p.m., according to the San Francisco Police Department, the 23-25-year-old male suspect struck, approaching the victim "from behind on his bicycle."

When he reached his target, he wrapped his fingers in her hair and "dragged her for a few feet," according to the SFPD report on the incident, eventually wresting from her her cell phone and school identification.

The victim was left with non-life-threatening "pain to the head," police say, but declined further treatment. The thief, who pedaled south on New Montgomery following the heist, remains at large.