My first question is if you're using a stock / "complete" CC or built your own.
If you are using the stock, the crank can be set up as a standard or compact double, and has mounts for a 3rd chainring. You will need a different bottom bracket and front derailleur to switch to a triple.
The rear derailleur is Tiagra, so it's a bit limited in range -- 11T-27T. 48-36-28 with an 11-27 is passable for touring, although not as wide as you'd get with MTB parts where you could do 48-36-26 with 11-34. (The infamous Sheldon Brown / Harris Cyclery suggests that Shimano is conservative in their listed range, as yet untested by yours truly though....)
I've found friction shifting with a triple is a little annoying, as you need to tweak the FD position when shifting the rear. I plan to stick with it though, as there are other advantages to the bar-end shifters.
You might want to try a 48-32 up front and 11-27 in back. If that doesn't work, then look into either a wider rear (if you dare), a triple or MTB bits on the back.
Last edited by Bacciagalupe; 04-02-08 at 06:55 PM.
Reason: quick tweaks