Originally Posted by dsbrantjr

hyhuu: Just a guess but the chain makes a more acute bend (each link bends through a sharper angle) going onto and coming off of the smallest chainring. I'd think you would notice the same effect on the smalller cogs as well, though. The tension provided by the derailleur is lower and the derailleur wheel angles are different on the smaller chainrings and cogs, maybe that makes a difference.