All force transferred along the chain that is normal to the chain-pin axis is the most efficient from a load-distribution standpoint. Forces are evenly shared by both inner and outer links, and side-load to the gear teeth is minimized. Any oblique angle of force in the chain line will apply more pressure on either the inner, or outer link, increasing material deflection, as well as more side-contact with gear teeth, increasing heat, and increasing friction. Reducing the force in the chain will decrease friction in the pins and gear teeth at normal and oblique angles, but minimally with the gear teeth, as there will be more contact with gear teeth under side-load.

All that taken into consideration, however, still means the difference will still be immeasurable with the +/- 2.5% accuracy error of most consumer-available power meters.