First off, this is on a compact FSA SLK crank set and 105 cassette, RD and FD which came stock on my '06 Roubaix Comp.
I've been noticing the rear derailleur has been shifting a little funny, so I sat down with the bike today and did the full adjustment down to resetting the cable tension and the H and L screws as well as the "B" screw. That all looks fine and dandy, and the rear shifts perfectly now, but it didn't change the situation with my FD.
It doesn't happen all the time, but if I shift from the small ring to the big ring, it can drop the chain. After I set the RD, I went to the FD to check it out. I made some fine adjustments, but it was more or less perfect as it was. It's in line with the crank set and about 1mm clearance between the inside cage and chain on the small ring and largest rear cog, 1mm clearance from the outside cage to the chain on the big ring/smallest cog.
I kept trying to throw the chain and successfully did it a few times. If I do it slowly, it seems like the chain is just out of alignment to the point that the chain link plates on the inside of the chain are riding the teeth of the big chain ring. If you spin it fast enough, it just falls off.
So I guess I came to the conclusion that I need to be in the middle of the rear cassette in order for it to be lined up with the big chain ring, otherwise, the slight angle of the chain might pull it off of the chain ring. But it seems to me that I should be able to shift from the small chain ring to the biggest while in the 2nd or 3rd smallest cog in the rear without throwing a chain.
Am I missing something in the FD setup or do I just need to fix my shifting habits?
Edit: title should read "Limit screw OR shifting issue."