I have a 105 compact crank double with Ultegra deraileurs and Ultegra flightdeck brifters. I want to switch to a triple crank for loaded touring. What do I have to do and replace. I am thinking of the 6603 Ultegra cranks. I currently have a SRAM OG-1070 11-28t cassette. Do I need a long cage rear deraileur? I saw that the Ultegra recommends not to use more than 27t cassette. Any help would be great.