While on an extended tour last fall, we got caught in the rain and subsequently had some rear derailleur shifting problems on our 2005 Burley Duet that were eventually linked to a rust problem on the cable guide under the excentric bottom bracket. We cleaned it up as best we could and replaced the cable, but now it's time to solve the problem for good.
Obviously, I need to sand, prime, and repaint, but I'm concerned that I'll just have the same problem again because I assume the problem was originally caused by the cables scraping away the paint inside the guide and allowing rust to begin forming.
Does anyone have any recommendations of anything I can do to "line" the steel guides on the bike? I think I've heard that you can buy a real small diameter cable housing, but I'm not sure how or where I could attach it. I've also considered filing off the existing cable guide and trying to install a different plastic version, but the idea of trying to drill and tap a new hole in the bottom bracket shell to attach it is a little intimidating to me.
What are my options?