Saw this thread and it seemed applicable to problems I noticed this weekend...I also just got a new bike with the new Tiagra shifters on them. Went for two rides this past weekend and a lot of time I felt like I couldn't get get the chain to stay in a gear very well. I occasionally heard it make sounds like it was dropping a gear and heard a decent amount of clicking as if it wasn't completely in a gear sometimes. My bike is a cannondale caad9 5, brand new '08, so I'm a bit concerned but being new to this it could very easily be user error.