My visor clicks in with four little plastic pegs. I leave the two on the side attached but pop out the ones in the middle, so the visor pivots up and down. It mostly sits partway up the front of the helmet and out of the way, but when I find myself riding right into the sun or into headlights, I can pull it down. I ride drop bars about even with the saddle, so when the visor is down it definitely blocks part of my field of view, which is usually annoying but occasionally useful.

I don't think I invented this myself, but I forget where I got the idea. I've never assessed the effect in the mirror. I assume it looks incredibly dorky. I think it's a good system, though.