Originally Posted by
Retro Grouch
The greater diameter difference in chainrings the less smoothly it will shift. A typical triple will have around 10 teeth difference in chainrings. A compact double will typically have a 14 tooth difference. I'm not saying it isn't going to work, just don't expect it to be smoother.
My 50-34 compact setup (FSA carbon compact pro) does not upshift as fast as the 50-40-30 (Campagnolo Racing-T, 8 speed vintage) it replaced (same chain stay length, same rear cogs, new Campagnolo CT compact double front derailleur). I haven't a clue how much of that came from the significantly larger difference in chain rings and how much is the different pinning and ramping (Campagnolo and Shimano tend to be a lot better than other companies).