I went from 25 to 28 on my 8 speed Allez. The difference was noticabe on hills. I have a triple up front with a 30t small ring. I don't see any gear ratio spacing issues. I have a 6 speed 34t Megarange on my Super Course, and that gear spacing is noticable, but a good compromise on hills. The SC has a Sugino Triple with 32t small ring.