While changing my tube in the flat I got last week, I noticed that the the cable guide under the bottom bracket (pedals) was broken. I picked up the part and a new cable, and replaced it (the first time). I didn't have any problems doing that, and even adjusting the derailleur settings afterward went smoothly. There was only one problem that I had that I didn't anticipate: cutting the cable short. Originally, I had hoped to solder the end so it wouldn't fray as I do not own one of the cable end covers or the tools needed to put it on. However, the solder didn't stick to the cable. I looked for some shrink tubing but, lacking that, settled for some of the edge molding that you use to hold the screens in on screen doors and windows. It had a hole in the center, and fit quite snugly. I tried to melt the end a bit, but that didn't work that well. We'll see how well it holds up. At least it looks better than just wrapping it in tape, which is what I did last time.