Midsole
The Flyknit Racer’s midsole is constructed from Nike’s Zoom material. It’s firmer than their Lunarlon material, yet just as light and offers an incredibly responsive ride. Initially, some may find the feel a little too harsh, especially if they have never run in racing flats before, or have come from traditional cushioned shoes. Putting a few miles through the Flyknit Racers will break them in and the ride will soften up slightly. I can only describe the feeling as being full of feedback; I know exactly when I’m running on tarmac, concrete or grass based on the feeling underfoot.
The Zoom Air unit is located in the midsole area. This shoe is ideally suited for runners that land on their toes or mid-foot. Lighter-weight heel strikers could possibly get away with this shoe over shorter distances, though I would be cautious about venturing into anything above a 10k for fear of injury.