I've got an 11-32 9-speed in the rear and 50-34 up front. The bike is for both racing and occasional all-purpose riding. The 34 is for the bulk of the cross racing and both chainrings give me a wide range for all-purpose riding. For you, with a 12-27, You might want to consider a 48 and either a 36 or 34. I live in the mountains and both the riding and cross racing are hilly. Good luck and have fun!