Re recent mentions of supershoes and Biopace, and quoting myself from post 65:

So: power is applied to the right pedal from 2:00 to 4:00. Bottom bracket swings to the left.

As the right pedal moves through 6:00, the left pedal moves through 12:00. Rider begins applying power at the left pedal at the moment that the bottom bracket begins to swing back to the right.

Instead of an abrupt transition into the application of pedal force, the left pedal retreats slightly down and away from the foot, increasing the length of time during which the full pedal force comes to be applied.

The recent arrival in the running world of "super-shoes" might represent an analogous phenomenon.