Some of the dropouts available as static drawings include flat mounts. These dropouts include: DR2070, DR2071, DR2074, DR2075, DR2085, DR2086. For more on dropouts as static drawings, see: bikecad.ca/dropouts_from_static_drawings.

You may not be using any of these dropouts. However, if you select one of them and then switch the dropout menu from "Define by static drawings" to "Define by parameters", BikeCAD will apply all of the specs related to the flat mounts to a new parametrically defined dropout. You can then convert the dimensions for the dropout to better reflect your actual dropout. If you change the Cx dimension to something smaller, then the flat mounts will be attached to the chain stays and not to the dropouts. Remember, you can also change the Angle 1 dimension in the disc brake dialog box to shift the angle at which the flat mounts are positioned.