There are no shortcomings in the Zoom Fly’s ability to help runners of all abilities run faster. The midsole configuration of resilient EVA plus midsole plate is remarkably effective for transition of energy from one foot strike to the next. Comfort is compromised a bit with the narrow forefoot and rigid all-around construction, but if you’re cool with the fit, the Zoom Fly is an ideal shoe for fast track workouts up to marathon racing.
The Zoom Fly has a form-fitting racing last and construction that wraps the entire foot like a glove. The forefoot is relatively narrow and is designed for racing rather than everyday mileage. Flywire cords looped into the laces on the medial and lateral sides lock-down the upper to the midsole platform. Some of our testers reported the arch support runs too far medially.
In the rear foot, the Zoom Fly has a high and rigid heel cup with moderate padding around the ankle collar, which wraps the heel securely but can also cause some friction. The seamless one-piece Flymesh uppers are extremely comfortable against the foot and are completely flexible to move with your foot. The thin tongue has a small cut groove that allows wider range of motion from the foot and ankle. Underfoot comfort is outstanding in that impact from the road surface is barely felt.
Two advanced technologies in the midsole contribute to high responsiveness in the Zoom Fly. Ultra lightweight Lunarlon foam gives a soft and resilient feel on impact, and a full-length carbon infused nylon plate provides stiffness and creates propulsion from heel strike to toe off. The shape of the plate is roughly equivalent to the black line on the midsole, dipping low at the forefoot and curving upward again in the toes. The bounce from the Zoom Fly is the most pronounced of any shoe in our test group, and the full spring helped our testers maintain leg energy during longer training runs.
The tradeoff for having a stiff midfoot plate is that the entire Zoom Fly shoe is very rigid, with almost no flexibility for natural movement in the forefoot. There is enough resilient cushioning underfoot to make the entire stance phase very smooth, and the transition from heel-to-toe is effective even over long distances. The midsole geometry (10mm drop) is ideal for heel strikers but will leave midfoot runners scuffing the rearfoot. One change our testers appreciate in the Zoom Fly outsole is the more prominent use of high abrasion rubber in the heel and throughout the entire forefoot, which improves road traction in stance and grip at toe-off. It also improves the overall durability of the shoe in comparison to the company’s recent trend of just using EVA on the bottom surface.
Testers described the Zoom Fly as a track spike with a ton of cushioning; others said it feels like they’re running downhill all the time. The Zoom Fly is clearly built for speed, and easily facilitates fast leg turnover and snappy foot strike at high velocities. This shoe is highly recommended for a casual runner who wants to train at faster speeds, or as a long distance race day option.