Originally Posted by Madison

The C-Base makes it impossible to adjust the center-center distance between wheels, so while things are an even number of pitches between wheels, the gearbox isn't an even number of pitches without shimming it upward some. This might be fine, but the tensioners also up to get the chain away from the floor; it isn't always necessary to do that, but I try to do when I can.

What software are you using to to open the STEP file? STEP should be a platform neutral format.