The bicyclist who died in an accident last week in Medford was identified Thursday as a fourth-year medical student at Tufts University. Mohamed “Moe” Zeidan, 29, of Somerville died Sept. 5 after the bike he was riding collided with a motorcycle on Route 16 at Interstate 93, officials said. Tufts said Zeidan, a native of Minnesota, worked as a community service leader and was an All-American soccer goalie and student body president as an undergraduate at Amherst College. After graduating from Amherst, he spent two years as a research assistant at the psychiatry department at Massachusetts General Hospital, work that led to being published in peer-reviewed journals and invitations to present at national meetings. Before arriving at Tufts, he volunteered for a public health organization in Uganda.