Bicycle Mechanics - Is this symptom of a front derailer problem?

I have a compact double.

When shifting from the small to large ring the chain sometimes does not catch. After a couple seconds of pedalling or trying to shift up again, the chain moves. I have a feeling the derailer is not moving far enough to the right.

And then sometimes when down shifting from the large to small ring (usually happens when I'm going downhill for some reason) the chain comes off the rings. I think it's going too far to the left.

So overall I think the front derailer is too far left... such that shifting up sometimes doesn't catch... and shifting down sometimes drops the chain. I think this is a reasonable diagnosis. But what can I do?

Thanks for the help! BTW, finally donated, does it usually take time for the red star to appear?

This link should help: http://www.parktool.com/repair/readhowto.asp?id=75

Sounds like an adjustment problem, but also remember that front ders shift best from the small CR to the large CR when you are applying very little pressure to the pedals. Even the best set up will balk if you try to shift when you are hard on the power.

A counter clockwise turn of the barrel adjustor will move the derailleur to the right, but there could be other reasons for your particular problem. Using the instructions at the Park Tool website is a good recommendation, but they need to be done carefully and in sequence.

Al

Yes that web site is great. I adjusted both derailers last month usng that website. and after a short ride and an extra 1/4 turn here and there my 30 speed shifts perfectly.