In BikeCAD, you've always been able to control the bottom bracket position by either BB drop or by BB height. In BikeCAD version 23, you can now also control the bottom bracket position by Pedal axle height which is the height of the pedal at the lowest point of the stroke. When using this driving dimension, as wheel size changes or as crank length changes, the Pedal axle height will always remain set to the desired value.