Quote Originally Posted by VeloMel View Post
I can change out just one chain ring? Wow I learned something new today! If I change out my cassette will I have to change the deurailler (sp?) And chain too?
No, I think you have to change the whole cassette but others might know more about that. I was just referring to the fact that what you will really notice is the new 28 teeth cog because the rest of the gearing on the 11x28 will be very similar to your current cassette.

For example, your 12x25 cassette is probably 12-13-14-15-16-17-19-21-23-25.

Those numbers represent the teeth on each cog.

When you switch to the 11x28 you might get, lets say:
11-13-15-16-17-19-21-22-25-28

I don't know for sure which 10 cogs you will get (I just guessed at those above) but you as you can see, much of the gearing will be identical to what you already have, what you will really notice is the 28.

Also, looking at Sheldon Brown's site and the gain ratios that different front chain rings and different rear cassettes would produce will show you that all these set ups will have lots of overlaying gears. You just need to figure out which hard gears you need for speed and which light gears you need for climbing based on your experience with hills and your current gearing.

I'm not sure if you would have to change derailleur or chain. I'm not knowledgeable enough.