A tool for precisely determining the height and setback of a bicycle seat so that the seat can be adjusted to desired parameters. The tool can also be employed to determine the exact height of a bicycle's frame. The tool includes an adapter member that is attached to the bottom bracket spindle of the bicycle after removal of the crank arm. An elongate measuring pole is attached to the adapter member. Measuring indicia are inscribed on the outer surface of the pole. The measuring pole is provided with two components adjustably positioned along the length of the pole. One component is adapted to attach to the frame of the bicycle. The second component includes an adjustable position rod.