mix left shifter and font derailleur of different speed I have a Shimano 5700 front derailleur and 5700 flat bar shifter (left) but for some reason I can't use the FD on my frame (too narrow, my driven train is 9 speed). After lot of research some people suggest using Shimano 2400 FD (8 speed). I am going to try but my question is can I still use the 5700 flat bar shifter (left), which is for 10 speed driven train?
It will work OK while you should not mix 2 &amp; 3 speed (MTB and road) front gears. 8 speed chain is a little wider than 9 speed and the FD will be a little wider but it's not much wider and will move your chain pretty nice. It's not affecting the shifter cable pull and FD move.
The problem in mixing 8 &amp; 9 gears is in rear shifter.