I live in area where I ride some pretty serious hills for about 80% of my mileage. I have a 2005 Felt F80 that I bought used last spring and feel that I need to look at some re-gearing options to make these hills more manageable. What I am contmeplating is finding a way to drop the size of the smallest front ring down about two teeth while leaving the middle and large ring the same. My question is this: (since this is my first bike of this caliber), is it possible to change out just the small ring or does one have to change the entire ring-set (or crank set) to accomplish this goal?

thanks in advance