>>1546806You literally can't commute in a pursuit position with full aero suit and narrow tubulars at 160PSI, brakeless, with a single tall gear.
It's simply unfeasible on real world conditions: you can't see where you're going, you can't stop quickly, you can't coast, you can't get up to speed quick enough, and you won't get a mile in before the tires either get fucked by glass or have you wipe out.
Also, messengers ride with bags/cargo racks and a lot of them like risers for stability and visibility, both of which shit on aero, and ride extra tough tires that roll like shit. The fixie messengers aren't even a sizable fraction once you tally all of them in, either.
Regarding drivetrain efficiency, have a look here and it's sources:
https://dorkythorpy.blogspot.com/2014/03/hub-gear-efficiency-vs-derailleur-gear.html3 speed hubs scored similar to derailleur systems but hubs with many gears are indeed less efficient, also if the graph you posted was normalized to the singlespeed efficiency to isolate hub losses it wouldn't look as if the difference was huge as it does there with that and the truncated Y axis
