I have 2 pairs of rollers. one pair are grey and the others are what my friend calls "Reds" the cock in this pair is a very deep roller and ends up hurting himself, one time so bad he is now blind I only let him and his hen out when the rest of my birds are in just in case he sets of flying with them.
In all your opinions what actually makes them roll, I think it's sometimes showing of. My friend say's it could be some kind of dizzy spell. I let mine out everyday and most days they roll.