Personally, I rotate the barrels all the way in and then back it out about a turn or turn and a half. That way if the cables are initially too tight, I have a little wiggle room, but plenty of room to allow for housing compression. On one of my bikes, I set it up without barrels (Cannondale-Record- Nokons), and to be honest it's fine. It took a couple times on the stand to get fully dialed in, but after that, no worries.