OK, I bought a Motobecane Sprintour frame online. It is only a couple of years old, and I wanted to build it up with mostly Shimano parts. I noticed that the frame had downtube shifter bosses. There is only one set of cable troughs under the top tube and a plastic cable guide under the BB housing. I am wondering if I am going to have some issues with cable routing when I start putting it together using STI shifters? If so what should I do?