Can you convert a bike with internal cabling to external cabling?
The short answer is yes. All you need on almost any Bowden cable-operated brake or rear gear mech is to run the housing in one length from the operating lever to the mechanism, rather than having a break along the way with bare inner wire visible. Life may be a bit harder with a front gear mech, since few, if any, made today have an integral outer casing stop. Ingenuity will be needed to provide a rigid stop for the housing. You’ll also need to find some way to keep the cable neatly secured to the frame – zip ties or similar will do the job. It may be tricky to find a suitable length of housing; the bike shop will have reels of housing, which will make life easier.
Technical Editor, Cycle magazine