The Motorcycle Safety Foundation that sponsors motorcycle training courses. The backseat on a motorcycle for its passenger.
Rake is the angle of the fork away from vertical toward the rider.
Trail is the distance on the ground between a vertical line dropped straight down from the center of the wheel and a projection of the fork extended until it touches the ground. As the rake increases, the trail increases. The more rake, the more stable the handling. A gathering of motorcyclists. Could be any number as small as 50 or as large as 500,000.