Originally Posted by
son_of_clyde
This sounds questionable because given the same gear ratio on the same bike, the angles between the chain/sprocket tangent points are the same, resulting in the sum of the angles subtended by the links to be the same regardless of sprocket size (ratio held constant) - basically big sprockets mean more links at less angle and small sprockets mean less links at more angle.
Was just thinking about this again - smaller sprockets (given same ratio) leads to higher chain tension which leads to higher friction, which results in bigger sprockets indeed being more efficient (at steady state anyway).