Nike Free

Nike Free is a running shoe built around the way a bare foot moves. Nike says the first model followed measurements by Tobie Hatfield and Eric Avar of the foot running unshod, after Hatfield watched a track team training barefoot. The benchmarks Nike lists are a balanced heel-to-toe pressure gradient, a 33-degree toe-off angle and a more neutral pronation pattern, and it says the shoe sets the 52 muscles of the foot free to work.

That flexibility is graded on the Free Scale: the lower the number, the closer to barefoot. Nike describes the fit as shaped to the anatomy of the foot. This hub lists every Nike Free model from the shops we track, with sizes in stock and the checked date.