Trail Runner’s Shoe Review: DYNAFIT Ultra 100

Trail runner Sarah Barber reviews the DYNAFIT Ultra 100 trail running shoes, which were provided at no cost by DYNAFIT, a corporate member of American Trail Running Association.

Those who made it past high school physics know that a dyne is a derived unit of force—specifically the amount of force required to accelerate a one-gram mass at a rate of one centimeter per second squared. In other words, it’s a teeny tiny fraction of the better-known unit of force, the Newton. Physics aside, all runners know that the best kind of force is the kind that propels you forward, and that is exactly what the DYNAFIT Ultra 100 is designed to do.

Visually Explosive

It’s not difficult to quickly identify a half-dozen trail shoe brands that have a model with the word “ultra” in the name. This speaks to the growing popularity of trail ultra running, as well as the shoe producers’ market awareness. However, the chunky, clunky sneaker image associated with the concept of trail shoes built for ultra running is a far cry from DYNAFIT’s new Ultra 100.
The hot-coral-blueberry color scheme on the women’s shoe is visually explosive…like dynamite. And if the “dyn” in DYNAFIT invokes memories of high school physics, the Ultra 100 is here to defy the law of gravity. An item appearing to have a certain robustness to its mass can’t possibly weigh almost nothing, can it? Well, yes, apparently it can. Tipping the scales at under 270 grams, this hollow-boned beast just needs to sprout a pair of wings and it would fly.

The Fit

The Ultra 100’s hot-rod hips sit atop 4 mm lugs made of the Vibram Megagrip Blend and taper all the way to the toe. Maybe that tapered toe makes the shoe aerodynamic? It’s reinforced to prevent stubbed toes from inadvertent contact with rocks and stones, but the rigidity combined with the narrowness might be a little unforgiving for toe number five. Anyone between sizes should therefore err on the upper end—particularly given that non-negotiable gift of long distance running: foot swell. Generally speaking, the Ultra 100 has a secure fit with a seamless tongue and a lace cover to satisfy the compulsively tidy, minimize pressure points, and discourage the gremlins from messing with your shoelaces.

DYNAFIT Ultra 100 on the trail as tested by Barber.

The Feel

It’s rare that a shoe named “ultra” feels speedy when the pace gets spicy, but when I leaned into some pre-workout strides in the Ultra 100s, my first impression was along the lines of Formula One. The only thing missing was the snarl of revving engines. The web-advertised “dynamic, fluid roll-through” enhanced by the rocker-shaped sole is no lie—these kicks are made for speed over distance. The 30 mm stack height might give the illusion of cushion, but if your wish is for squish, move on. Personally, I loved the brisk, responsive feel on all terrain as I galloped over some hills and through a shallow stream. Giddy up!

While the Ultra 100 can certainly handle any amount of training mileage thrown at it, its true capacity will be revealed in race conditions. When you consider that running a 50K requires lifting one’s feet more than 60,000 times, wearing lighter-weight kicks will get you to the finish line faster. Couple that with just enough midsole mass to provide that Newtonian equal and opposite reactive force against the ground, and now you’re in contention for the podium. If we’re talking about a chance of winning, the DYNAFIT Ultra 100 is a no-risk bet.

Proven Commitment to the Mountains

As a brand, the DYNAFIT dynasty is a young one at less than 100 years old. But in that short span of time, the company has proven its commitment to the mountains—and not just for humans engaged in endurance sports. The company’s logo features a stylized snow leopard, a creature that embodies what DYNAFIT products confer to athletes: the ability to thrive in barren alpine conditions with speed, endurance, silent elegance, and sure-footed confidence. DYNAFIT backs their animal passion with dollars and public relations work for the Snow Leopard Trust in the Pacific Northwest. I don’t know about you, but the next time I trot out to nail some trails, I know I’ll be channeling my inner snow leopard.
Weight: 269 grams
Stack height: 30 mm
Heel-toe drop: 6 mm
MSRP: $169