It took maybe a year after they were introduced for me to try the Nike Free shoes. I ran two blocks and sold them.
They said it would make my foot free, I said it felt like I was running on wet tar. Funny then, that just a year or so later they began putting carbon fiber plates in their road racing shoes. Free, my butt.
The question: How fast would Kipchoge have run the sub-2 effort in Nike Free shoes?