Eusebia Ramirez's lawsuit charges Police Officer Edward McClain of "carelessness and recklessness" in her son's death on Aug. 11, 2012.
Her lawyer told the Daily News that Ramirez's 28-year-old son was supporting her financially and emotionally. Edward Steinberg said McClain violated NYPD protocol by chasing the unregistered dirt bike. He remains on active duty.
The lawsuit was filed in the Bronx on Monday.
The city Law Department said it had not yet seen the lawsuit.