I'm looking for a new f.d. and am aware that they are sold according to how many gears are at the rear and how narrow the chain is.
I have an 8 speed set up, can i get away with a 9 speed shimano ultegra front derailler?
There are meant to be some differences in the front derailleurs, but for what it's worth, I'm having no problems running a 9-speed Tiagra front mech (triple) with 8-speed Sora shifters + casette and a 10-speed Ultegra rear mech.
Can't really see that there is going to be much difference at all between an 8 and 9 speed front mech - in reality it is only a 2 speed changer (or 3 speed on a triple), and it is the shifter and limit stops that control the extent of movement. The cage width may vary minimally too of course.