The only thing about it is that the seat position was just right. I gradually learned to balance the seats curves where it widens in the back between my leg muscles to make it act as a kind of block lock, so that when I crank the pedals, my feet are forced against pedals, and the tops of my legs are chocked into the back of the seat curves. And it pops! The speed gains are excellent. It keeps up with traffic. Hehe.
I notice it's a mix of nuanced talent and leg power/stamina to be able to time and balance that maneuver right.
It won't work though if it's the wrong kind of seat, or the combination of pedal, crank, BB, and seat proportional proximity isn't just right. I need to experiment around with this to get it down to a science.