BikeCAD uses the threadless stem standard for defining stem angle. To measure the angle of a stem, we place the stem on a horizontal surface and measure the angle that the stem rises above the horizontal. Because most treadless stems are reversible, a stem with a 10° rise could be flipped around to serve as a stem with a 10° drop. In BikeCAD, a stem with drop could be attained by assigning a negative value to stem angle. Some examples of stem angles are shown below.