Yes, you can use Brake cable housing for the rear derailleur cable loop. Per my experience many bikes came that way from the factory anyway. The brake housing tends to be a little bigger in diameter than proprietary derailleur loop housing as supplied by the derailleur manufacturers, so sometimes you cannot fit a ferrule at the tips to go into the stops unless you have a stepdown on it small enough to fit the chainstay cable stop. If you take the plastic skin off the brake cable housing, it usually fits nicely into the chainstay stop, so most of the time people just dont use any ferrules. Same goes for most stops on rear derailleurs.
Or....you can also just try and find yourself some Campagnolo spring cable loops that have the proper smaller diameter and ferrules that fit the RD and chainstay cable stops if you want a very nice looking installation. Just look for Campy part number 617. They look very nice and period appropriate on most classic and vintage bikes. I recently obtained a suplly of these for my bikes after a longish search for them at ebay. I finally snatched a few of them about a month ago, so although not that common out there anymore, they still pop up with most Euro eBay sellers once in a while.
Chombi
Last edited by Chombi; 06-23-10 at 06:48 PM.