Shimano 105 front derailer problem

gsk82
gsk82 Posts: 3,527
edited May 2009 in Workshop
I've just bought a Focus Cayo from wiggle. been out on it a couple of times and most of the time i can't change the front gears at the first attemt. I've stood it upside down and tried and it works fine and a local shop made slight adjustments and it worked fine on their stand. however as soon as i start riding it it all stops working, the derailer is moving but the chain isn't following.

I've been using sora kit until now, is there something i'm doing wrong with my gear changes?

Cheers
"Unfortunately these days a lot of people don’t understand the real quality of a bike" Ernesto Colnago