Chain overshifts small ring

[j beede]

I thought this would be a trivial fix--just turn in the "L" screw on the front derallieur. No such luck. I have L turned in as far as I can without making the cage rub. When shifting from the middle ring to small with the rear on the largest gear the chain occasionally shifts past the small ring and falls onto the bottom bracket shell. The FD is a Shimano 105 and seems to be set at the correct height (~1mm clearance to big ring) and outer cage is parallel to rings. Ideas?
...j

[Alex Ramon]

Hmmm, that sounds annoying. Sounds like you've set everything up properly, as the "L" screw is usually the one to adjust to stop over-shifting onto the bottom bracket.

Maybe you have a really wide range between the large and small sprocket? Have you ever replaced individual chainrings for custom gearing? Post some pics of your setup if you can!