So I've been having trouble with front derailleur lately. I made some adjustments and after hours of swearing and getting ready to throw my bike in the garbage I finally got the stupid thing to work.

Then I decided to go for a test ride up the street. Well, all of sudden while riding the front derailleur no longer worked. It wouldn't change gears and when it did it just threws the chain off. Ok. Fine.

So then I put the bike back on the stand and was going to fiddle with the thing, but before I did I decided to check it out one more time. I turned the cranks by hand and shifted through the gears. I was perfect! I hadn't done a thing. WTF?!

Another test ride...nada. It was all f'ed up again.

WTF?!

What is happening here?