Ed Holland

Hi Geoff
Lets have a look at the mechanics of your problem anyway. The Front derailleur (in all the types I have seen) moves toward the larger chainrings, outward from the frame, as the cable is pulled tighter by the shifter. Slackening the cable by action of the shifter allows the derailleur to move towards the frame, and to the smaller chainring(s). The derailleur mech has a spring built into it that allows it to relax to the smaller chainring positions when the cable is slackened. From the above posts, it seems like your shifter is ok - the cable slackens - but the mech is refusing to shift the chain. There are a number of possible reasons of this;

1 Derailleur is stuck due to dirt and or lack of lubrication
2 Cable is trapped or sticking somewhere (perhaps where it leads under the bottom bracket)
3 The return spring inside the derailleur is weak/broken
4 Somehow the limit screws on the mech have been adjusted so that shifting is prevented (unlikely)

To start with, I'd suggest playing with the shifter to see if any movement in the derailleur can be observed. A clean up, if necessary, and a drop of oil on the pivot points of the mech would not hurt it. Also trace the cable along its length to see if it is the cause of the problem. If you are unsure about tinkering with this, it sounds like an easy job for the bike shop

Ed