I would like to add low rider bosses onto a steel fork using silver solder. I have seen the external ones that mount on the front of the fork. The other fork I have has the bosses in the side, which puts them in shear. I think that is good for durability.
In the side type bosses there is a hole on the opposite side, the inner side, of the fork.
What does this inner side fitting do? Is the bolt that mounts the pannier supposed to pass all the way through to reduce the bending moment on the outer boss?