I changed the bars on my Prince from a 46 to a 42. Since the cables were about 18 months old I decided to take the opportunity to change those at the same time. I thought I was smart to cut the cable and just leave the ends in the RD and FD so I could make sure to rethread those correctly.
I thought it might take an hour to replace the bars, rethread the cables and retape the bars. I've done some faster.
However this was my first experience with Campy Ergo shifters. It was also my first experience rethreading the rear brake cable back through the top tube.
The cable in the Ergo shifters make a really sharp turn after threading it into the shifter and just before leaving the shifter. After numerous attempts I never could figure out how to get the cable to make that turn and get it into the hole leaving the shifter. I even damaged one cable beyond repair trying one approach.
In addition, I never could get the brake cable rethreaded back through the top tube. Surely there was a guide tube inside the top tube for the cable????
So, after almost 3 hours of I put all my parts in a box and took them to the LBS where I'd bought them sheepishly asked them to put it back together for me. When I get time I've got to find out how they did it.