Edit the dimensions of your Motorcycle Chassis. The castor angle determines in which angle the linkage is put in. Position of sprocket is entered in this window.
With custom bike files you can edit all motorcycle linkage dimensions. For .bk1 and .bk2 files the standard bikes linkage is allready in the data.
For cutom bike filePivot inserts, and ride height adjuster can be used, the main window gives a very direct feedback about changes to f.i. the anti squat.