Yes it does...(Respond to weighting) - the REASON the leaf wants to shorten/arc, after it reaches its resting position...is BECAUSE the tire/axle is pulling it down.

If the ends are ridgedly connected, it would be all but impossible to have droop past the resting (Relaxed) position...the swing inwards allows both the arc end distances to change during flex up, and down.

If a shackle doesn't allow movement of the leaf, it can't flex...as you correctly described....

...The more the shackle can move, the more the leaf can flex....and ALL the flex is in PROPORTIONAL RESPONSE to weighting.

(If the leaf has less weight on it, it curls towards its resting position...if it has more weight on it...it flattens away from its resting position...If the leaf is pulled down by the weight of the dangling suspension...is arcs PAST its resting position, etc.)

As the leaf pack curls, the shackle swings in...because the ends of the leaves are pulling closer to each other as the center is lowered (Droop).



The point at which we do a shackle bolt change is when the shackle is unweighted...that point at which there is no weight on the shackle, and, no pull down by the suspension...its at its neutral point.

A regular shackle, and a Revolver shackle, BOTH have this neutral point...that's how we install them for example...when they are unweighted.

The amount of droop to REACH that point is the only difference, all else being equal.