I'm interested in starting touring and have been looking at buying bikes (used if possible) and I see a lot of bikes that are called sport touring. What is it about these bikes that makes them not suitable for carrying full loads? what kind of terminology should I be looking for in a bike for loaded touring? Also, any recommendations for finding a used bike other than the LBS? I'm tall and they are not easy to find where I am.
Usually their frame are of a lighter tubeset, and there is a compromise in frame flex if they are loaded. They are intended for those who ride (a) randonnees or (b) credit-card touring where the load in each case is usually just a trunk bag.
For serious touring cyclists, the investment in a bike is a long-term one. Someone mentions in another thread a Jamis Aurora on ebay. Ebay probably is your best bet, but is fraught with the old fit danger.
Mounting a heavily loaded set of panniers off the rear stays or the fork requires tubing with a thicker sidewall than is found on most racing/sport bikes.
A loaded tourer is optimised to ride with a full load, so you have longer chainstays, more stable touring, more braze-ons, lower gears etc etc.
Check out Bruce Gordon for a good rant on sport bikes vs load-carriers, and Beckman Sakkit bikes for the ultimate loaded tourer.
Cervelo RS. Marinoni touring bike. Kona Tanuki. Specialized Harrock (commuter). Raleigh (early 80s) Super Gran Prix.
I have a Sport/touring bike and as well as thinner framesets, higher gears and shorter chainstays, sport/touring generally have lighter wheels (24-28 spoke) and dual pivot brakes. Where as for loaded touring it would be wise to have a beefier set of wheels (36 spoke) and better brakes for the heavier load (cantis or V brakes).
My sport/touring bike was custom made (Marinoni) and has a triple chainring but with a 52T large ring. The rear cassette is 11-25T. Although I have the braze-ons for front and rear racks I would not be able to carry a huge amount of weight due to the wheel set and brakes, plus the gearing doesn't make it easy for steep hills for loaded touring.
Sport/touring bikes are for lightweight loads/credit card tours, day tours, sag supported tours, fast/long distances (brevets). Can be used for racing if you want, but will have to comprimise on the gearing.