BikeCAD version 19.0 features the option to document the center of mass of a bike. The center of mass will have to be experimentally determined, but once known, you can locate the center of mass of the bike by horizontal distance X from the center of the bottom bracket and either by vertical distance Y from the bottom bracket or by vertical distance Y2 from the ground.
There are actually 5 different instances of center of mass. The first is meant for the bike alone. Next, we have the rider alone, then the bike and the rider combined. In addition, there's one for the rider in an out of saddle position and finally the bike and the rider in an out of saddle position.
Once one or more center of mass elements has been selected, we can add dimensions showing the distance from the center of mass to the front and rear contact patches as well as the angles formed between the center of mass and the front and rear contact patches.