Originally Posted by
operator
Mechanical efficiency with more teeth? Sorry, that doesn't make sense. If anything, the longer your chain the less efficient it is.
The bigger your cogs/chainrings the longer they will last.
I read about this somewhere (Sheldon Brown-ish no-bull**** place), that smaller chainrings and sprockets will cause more stress on the chain and as a result, higher friction losses.
Then there's that paper in "Human Power" that compared various gear systems - among them deraileur-equipped systems, and compared the transmission losses for various sprocket-chainring combinations. Even there, there was a trend to have higher efficiency (closer to 100%) with larger sprocket+chainring, although by no means a linear function.