Bicycle Mechanics - Campy front derailler cable explosion.

Picked up a used bike with Record ten shifters and deraillers. Noticed a small crack in the cable housing where it meets the cable guide hear the steerer tube as I was assembling the bike. I shortened the stem 10mm from a 130 to 120. Today during my second ride on the bike I noticed the front derailler was not shifting well at all. Lo and behold, the cable housing was completely frayed near the guide and kinking /binding the shift cable. What would have caused the housing to explode, as it is itself wrapped cable and plastic? I am ordering new housings. Should I shorten the housing at all or just slap a new one on?

Things come apart. Housing is flat spring wire wrapped in a spiral and perhaps water,
grease rust whatever caused the helices to delaminate. Maybe it was tempered incorrectly. Housing length should be within a few inches of the present length,
look at the way the present ones curve and if this is satisfactory match the lenght.
Get a new set of housings. Check the entire length of the brake cables just for
fun. I had a new Ultegra brake cable rust out just below the seat in 12months
on my Vortex. Campy is probably stainless but check just the same. Steve

I had this happen on the used bike I bought; the housing frayed and I couldn't shift. Just go ahead and change the derailleur cable and housing, it's easy to do and worth knowing how to do.

I am now assuming this resulted from shipping the bike and twisting the bars sideways to get the bars in the shipping box. This tweaked the cable housing causing the jack-in-the-box effect that I now am looking at. Do I need special tools to cut the cable housings to size? I have good wire cutters etc.

Housings can be cut with any tool that does not crush the spiral. You will need to
file or grind the end of the housing so it is flat afterward. Experiment with the old
housing first before whacking away at the new housing. You don't want ovalized,
crimped or crushed housing. Wire cutters would be used on a diagonal so as to slide between the spiral wire and cut it at one site. Cable cutting is not as easy as it looks either. Wire cutters tend to crush them as well resulting in unraveling of the cable that is hard to stop and makes it difficult to thread through the housing. Dremel type abrasive cutters do well in a pinch, if available. Steve