Efficiency of hub gears

There is a perception that hub gears are horribly inefficient but this is not necessarilty so. A number of studies have tried to quantify the efficiency, with greater or lesser success; the difficulties are explained below. Note that the efficiencies quoted in different studies cannot be compared with any accuracy - the experimental conditions are unlikey to be sufficiently similar.

A recent study compares 3-speeds, 7-speeds, a Rohloff and some derailleur systems. The 3-speeds come out as efficient as a derailleur, but hub gears with more than 3 gears were noticably less efficient.

Rohloff's measurements are more optimistic.