I live in Denver and ride alot up in the mountains (many sustained 15-20% climbs at altitude), and would like to dump my Ritchey WCS Compact Crank (50-34) (the original double was a 53-39 Ultegra) for a Ultegra Triple. My rear cogset is a nine speed 12-27. My components are all Ultegra (circa 2003). My question is will I need to change anything other than the crank, and if yes, what?