SPEED: Insanely light 1-ply upper, Strategic rubber, Speed platform
EFFICIENCY: Pace-tuned heel and a forefoot FastPod deliver optimized cushioning and maximized forefoot propulsion efficiency for the way you run
COMFORT: Wide toe box, Contoured heel pocket, Lively pace-tuned feel
z40 Design Notes
ENGINEERING SPECS: Average adult ranges for height, cadence, and body weight at this pace.
CUSHIONING: At 7 minutes per mile, your flight distance is quite long, which means you generate a lot of force on impact. To account for that specific impact force, we tune the reaction density of the heel and midfoot to optimize cushioning you get. Forget about "max" cushioning for some random runner in a magazine—the Z40 gives you the best cushioning when running within the pace zone. We call this pace-tuned cushioning. Pace-tuning is the only way to get the best cushioning in a running shoe.
PROPULSION: At this pace it takes a lot of force to propel yourself forward, so the last thing you want is a squishy, inefficient midsole. We’ve tuned the forefoot FastPods in the Z40 to deliver maximally efficient energy return given the forces at this pace.
DROP: Runners at this pace are usually light in weight and often midfoot strikers. With this in mind, we built a 5mm drop into the Z40. This helps prevent a negative heel drop angle upon impact.
SOLE DESIGN: Rocker design and fortified arch outsole for ideal propulsion. According to a recent paper on arch compression, forces on the arch are greatest during the push-off phase of your stride (not the impact phase). Many shoe designs carve out the arch area, exaggerating pronation during the propulsion phase of your stride. The Z40 fills the arch area to provide support during push-off, precisely when you need it most.
Why you need a pace-tuned running shoe
Everyone running in the 7 minute mile range wants the best cushioning possible but without sacrificing push-off efficiency. As you know, we all generate a wide range of both impact forces and propulsion forces while running. Those forces are intense at 7 minutes per mile, but much less so at 12 minutes per mile.
We’ve carefully studied midsole material and how it responds to running forces. We found that it’s not possible for one midsole foam to respond correctly to all paces. What does this mean? Midsole densities need to be adjusted to the speed of the runner. (Kind of a problem for all those running shoe brands that try to sell every shoe to every runner, irrespective of pace.)
Our research also showed that the propulsion forces in your forefoot and toe are greater than the impact force you encounter in the midfoot and/or heel. As a result, running shoes need to be tuned by both pace and between heel and forefoot, at least if you want the best performing shoe.
By adjusting midsole density in the heel and midfoot to the forces you generate at 7 minutes per mile, you get the precise amount of cushioning you need at that pace. Kind of like Goldilocks cushioning. Pace-tuned cushioning in the Vimazi Z40 ensures stability during push-off, plus the comfort and health benefits of reduced shock.
But you’d never want better cushioning to get in the way of a propulsive push-off. To get the energetic push-off you want, the forefoot has to be tuned differently than the heel. We’ve engineered the forefoot FastPod in the Z40 so that it specifically responds to the propulsion force you generate at 7 minutes per mile.
The result: The Z40 reduces shock while increasing efficiency when running between 6:15-7:45 minutes per mile (3:55-4:45 minutes per kilometer).