ORIGINAL: LouW
When the wing is operating at zero angle of attack, such as in knife-edge flight, there is no dihedral effect, hence no roll coupling.
I don't agree with that statement. It is a common mistake to say that when the plane is in knife-edge, in a climb or in a dive, the wing is at zero AoA... the AoA is forced by elevator trim and hence is alwais the same, provided that the elevator trim is the same.
To prove that, one of the way to trim the airplane pitch behaviour during KE is changing the position of the CG, which let's you chenge the elevator trim.
BTW, interesting thread!