Originally Posted by
blakcloud
My guess is that a front Shimano XT double will shift just fine on a compact road. Shimano's documentation says it can handle a 14 tooth difference but I suspect that they err on the side of caution. A compact is 16 tooth difference.
I had read somewhere that the MTB derailleurs (and chainrings) worked with different spacings than the road rings, so that you would never get a clean shift with an MTB shifter and a road or MTB derailleur on road rings (shifter pulls a different amount of cable.)
I'd check into that.
I know there are pulley compensators which make any system work with about any other system, but if it were me I would find out about cable pull and swing length and arc, or it might end up as one of those "No matter how I adjust the derailleur ... " situations.