How to play against bad bishop outside pawn chain

Question

I'm trying to understand general principles and common themes on how to play against a bad bishop outside of the pawn chain. In particular, I'm talking about the less sharp variations of the london system, slav, and caro kann(although I don't play the caro kann with either side). Think typical london system or 4. e3 slav where black plays Bf5 or Bg4. Are there any enlightening games or common ideas?

Answer 1

Two ideas that spring to my mind:

1. Harass the bishop, and threaten to trap it / exchange it for a knight, with moves like h3, g4 and Nh4.
2. Attack the squares/pawns the bishop has left behind, with moves like Qb3 targeting the b7 pawn, or Qa4 / Bb5 / Ne5 targeting the a4-e8 diagonal.

Answer 2

More to the point would be why do you think a bishop is "bad" if it is outside the pawn chain? The bishop on f5/g6 for black is a fine piece in the Caro Kann. It serves several functions, offensively and defensively.

That is simplistic and novice thinking.

More to the point is it can be considered "bad" if it cannot attack opposing pawns and only its own pawns, and if it serves no useful purpose.