According to the solo student pilot of the Piper PA-28-161, he initiated a takeoff on runway 29L, a 7,314-foot-long, 100-foot-wide, asphalt runway. As the airplane reached an airspeed of 55 knots, he felt the right wing "drop toward the runway." The airplane pivoted to the left and departed the runway into the grass. The right wing and the right side of the nose section impacted a taxiway sign. The right main landing gear assembly separated from the airplane, damaging an adjacent wing rib. The student pilot and an instructor flew the airplane on the previous flight, practiced takeoffs and landings, and reported no anomalies with the airplane. The student pilot reported no mechanical deficiencies during the accident flight. The reported wind at the airport, about the time of the accident, was from 260 degrees at 9 knots.