Drop refers to a change in the ground clearance of a motorcycle, which means the distance between the ground and the underside of the frame. If you are looking at a motorcycle frame or hardtail that is a 2 inches drop, that means the rear of the frame would be 2 inches lower than the stock configuration. If you would like the frame to sit level with the ground, this means you would also need to shorten the front end 2 inches. This can be accomplished by using different length fork tubes or raking the neck of the frame. Some builders are looking for a different stance, but be sure to properly calculate the rake and trail of the motorcycle to ensure proper handling.