Ok, here's the deal...my Giant road bike came stock with a Shimano triple 9 speed and I am thinking about changing it to a double crankset instead. The Trek Store I went to said with the Shimano 9 speed I can change my crankset to a double without having to replace my shifters or my cassette. Cost installed will be about $280.00. My question is, will this change improve performance very much. I never use the small ring on my triple. The triple crankset I currently have is TruVativ so I guess the Shimano will be an upgrade.