Just about any stainless steel "slick" inner cable works great. The "slick" cables are smoother on the outside than the regular cables and stainless is best in my opinion because they don't rust (teflon coated cables are usually just cheap carbon steel cables that have a coating on them that will wear off in short order thus allowing the cable to rust). For the outer cable, get the Shimano brand stuff. The generic cables tend to get stiff much faster than the Shimano brand stuff. Also, the outer cable for road bike shifters is smaller diameter than the off road stuff - 4mm vs. 5mm I think. The thinner cables work just fine and are less bulky which we all know makes you ride faster.
