Problem Solved... see Post #29.
My Giant Hybrid has a triple in the front cassette.
In the last ride in Fall 2013, everything was fine. The bike has been stored indoors at room temperature for all Winter. The bike has not moved, no derailleur adjustments made since Fall 2013.
Now I've noticed that the shifter will not shift into the granny gear (smallest cog in front). You press the shifter lever and it does not click and the derailleur does not move. The other 2 cogs can still be reached.
Based on my research on forums and watching many YouTube derailleur videos, it appears the cable tension must be reduced. But this brings up a better question: What caused the tension to mysteriously INCREASE?! I could see cable stretch over time causing a tension reduction, however, the tension increase at constant temperature and no adjustment makes no sense to me.
Any ideas on how this increase happened? Could it point to a larger issue that must be fixed?
Derailleur: Shimano Deore LX
Shifters: Shimano SLX