Yes they are necessary because the road brake levers do not pull enough cable to use the brakes properly. You can hook them up without the travel agents but the brakes will have to be so tight that the pads will generally rub on the rim under the slightest amount of wheel flex. There will also be a very spongy feel at the levers. The travel agents work great but be sure to either have a mechanic do it or follow the directions to the max. It might pay to have the lbs do it because on the first try almost everyone ruins a few cables because they get too kinked up.