For more than two decades, thousands of African American motorcyclists have traveled across the nation to South Carolina, to attend the Atlantic Beach Memorial Day Bikefest. On the last weekend in May every year, the low hum of customized choppers with high-handle bars and the high-pitched revs of neon-painted street bikes have sounded out on Ocean Boulevard. The 2015 Bikefest, however, was different. Ocean Boulevard, a two-lane commercial strip running parallel to the Atlantic Ocean, was partially closed. Hundreds of police officers enforced a one-way traffic pattern that clogged streets for miles and forced motorcyclists to idle in gridlock for...