Not dumb at all. I needed some in a hurry, did not feel like going to LBS. I tried to remove some from brake housing . Don't do that. OTOH, it is very easy to split some derailleur housing, use one of the metal wires inside to keep splitting the outside plastic, You will be left with a bunch of wires and the inside liner. You can even re-purpose used housing as long as you cut away the first few inches at the ends.