Originally Posted by
joejack951
In my experience an 8 speed chain on a 9 speed triple crankset can cause issues with the chain hitting the chainring ramps. A compact double will likely not have the same problem and several here have posted about successfully using 8 speed chains on 9 speed cranksets. You can always try it and see if it works. If not, a new 9 speed chain can be had for ~$15 and will work fine with the rest of your components.
if anything a compact double will be worse than a triple as far as chain hitting the ramps goes. 16t jump between the chainrings instead of 9-12 means the chain can't angle outwards as much. But if that happens you can fit it with thin chainring spacers.
That being said, I have found a compact double that is a 9 speed, as most seem to be. Assuming FD change to match this crankset, will I need to change anything else in the drivetrain to be sure of flawless operation? The only thing I can possibly see is the chain, to match the 9 speed crank.
My experience is you should match the FD with the chain, not the crankset. So use an 8 speed chain and keep the current FD, or 9 speed chain and change the FD.