When you flex the blank, the inside is the OPPOSITE of the primary spine.

Now, here's food for thought ...

1) The secondary spine is almost always NOT directly 180 degrees opposing the primary spine.

2) Would you want the "power" related to the primary spine to assist with a forward cast or backcast? Wouldn't that determine which side to build on?

3) What are you going to do IF the blank isn't straight? Which 95% arent. Are you going to have a "slice" or "fade" due to the failure of the blank to align with your actual cast?



BTW, I build on the straightest axis. It works just fine that way.