Originally Posted by
Andrew R Stewart
The laws of ratios pretty much control these questions. With the same gear size the differences of a multy speed system in the same ratio as a single speed are far smaller then one thinks. Portions of a % point of efficiencies, depending on pulley friction and chain lines. The differences are far more perceived then real.
This.
While there is some power loss to running a chain around the derailleur pulleys, it's a tiny loss because there's virtually zero tension in the chain's lower loop. The perceived advantage of SS vs multigear is mostly in the rider's head.
I've been riding fixed and derailleur bikes for 45+ years and. like many, appreciate the snappier feel of the fixed gear, especially in the city. Though when I was young, strong and foolish, I did centuries in the hills of Connecticut and PA with the fixed gear (no more).
Possibly one reason fixed feels snappier is that the wheel pushes the pedals through the dead spot. Another is that it forces you to ride more aggressively in rolling terrain, having to sprint hills since you can't afford to lose speed on climbs.