[QUOTE=The Chemist;13342439]Hello All,

Tonight I was riding home from work and I noticed that the rear derailleur suddenly became very difficult to shift. After a couple of minutes there was a snap and the rear derailleur cable broke inside the shifter housing.
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I've seen it happen quite frequently but never to my own bikes. I can only suggest that you replace cables as soon as shifting starts to feel balky or notchy.