Poor front gear shifting performance

"If your shifting used to be fine, your shifter cable may need to be tightened or perhaps the derailleur was knocked and rotated. Park Tools has published a pretty good guide on adjusting derailleurs, but your results may vary depending on the type and model of derailleur you have.

http://www.parktool.com/blog/repair-help..."

front derailleur usually has a 'over-shift' screw which keeps it from shifting too far and pulling your chain off the front casett. With riding this can rotate in/out.