When changing a flat, the time before last, I noticed the shift cable near the hub of my Nexus 8 was nearly completely broken. There was only a strand of two holding it together.

After a replacement cable was installed, when changing my next flat, the cable looked good, but I just noticed when changing yet another flat, the cable has stared to break again.

This time there is just a strand or two that's broken, but it's on it's way.

Is this normal? Do shifting cables break down this quickly?