What year is your bike? If you aren't sure you can measure the bb shell. If it is 73mm, it is bb30a, which I don't believe there is a conversion for shimano cranks yet.
The size of the shell also determines the spacers you need. Caad10 uses 7.5mm NDS spacer and caad12 uses 2.5mm NDS spacer for example, with the same 109mm spindle. There is only one spacer on the DS and one on the NDS with a wave washer. Beyond that you should only be using .5mm spacers to adjust compression on the wave washer. Adding a bunch of spacers to try and compensate for the wrong spindle will **** up the q factor. You can check ebay for some 104mm if you need one. Figuring out your shell width is your first step.
http://cf-prd.cannondale.com/~/media...150921T143755Z