Icebug Acceleritas8 RB9X Review

An in-depth review of the Icebug Acceleritas8 RB9X.

By on September 29, 2022 | Leave a reply

The Icebug Acceleritas8 RB9X ($140) is an ideal trail running shoe for runners who like to feel the mud beneath their feet, without taking it down the trail with them. It’s an almost minimalist, mud-specific trail running shoe with a very short stack height, 4 millimeters of heel-to-toe drop, and deep tractor-tread-inspired lugs. Its upper is constructed from a non-absorbent recycled polyester that both drains and dries quickly. It’s lightweight, coming in at 8.15 ounces (231 grams) of actual weight for a men’s size 9.

The overall fit is snug, without being remotely uncomfortable. Many shoes our team tested were far too narrow to make our best trail running shoes for mud guide, where we named this one of the best mud-specific shoes. And although this shoe was narrow as well, the upper was malleable enough that the narrowness didn’t feel constricting. Plus, it was redesigned this year with a slightly wider toebox, so it fit even wider-footed testers well.

If you’re no stranger to minimalist footwear and need a shoe for the sloppy times of year, the Icebug Acceleritas8 RB9X could be one worth trying.

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Icebug Acceleritas8 RB9X

The Icebug Acceleritas8 RB9X. All photos: iRunFar/Bryon Powell

Icebug Acceleritas8 RB9X Upper

The recycled polyester upper on the Icebug Acceleritas8 RB9X is almost more reminiscent in look and feel of a waterproof fabric than a mesh. It appears slightly meshy on the outside, but that mesh-like fabric seems to be laminated to a tightly woven, white inner fabric made to let water through but surely not debris.

As expected, this upper shielded our feet well from mud, grass seeds, pine needles, and pebbles. Being so non-meshy we also expected it to dry slowly, but one tester’s report proved otherwise. She said that the Acceleritas8 RB9X managed splashing and sloshing better than her phone, and that the uppers were dry after only about 10 minutes during a sunny high desert run that followed a full morning of rain.

This upper was designed more for thermal protection rather than quick drying, so it’s notable that it actually does both things well. We think the key here is using a recycled polyester that is exceptionally non-absorbent, to begin with. This fabric choice is a success.

There is a clear plastic rand made from recycled fishing nets that wraps the shoe. It is protective, which is important for such a malleable shoe, but also could theoretically make this shoe unwearable for wider feet because this plastic has no malleability at all. That said, the overall malleability of the shoe allowed it to fit a variety of feet well, from very narrow to fairly wide. We feel confident saying that despite its narrow last and the plastic rand, the shoe’s flexibility makes this a very user-friendly and adaptable shoe.

Icebug Acceleritas8 RB9X lateral view

A lateral view of the Icebug Acceleritas8 RB9X.

Icebug Acceleritas8 RB9X Midsole

The brand doesn’t report the thickness of the Icebug Acceleritas8 RB9X’s midsole, but it’s thin. This thin EVA foam is dense enough to be somewhat protective but malleable enough to give the shoe a nearly barefoot feel. The Acceleritas8 RB9X has a 4-millimeter overall heel-to-toe drop.

This all translates to a near-minimalist piece of mud-running footwear. The design keeps your foot low to the ground, which is exactly where you want it when things get slippery. This minimalism also means that you have to be careful where you step because the shoe has little rigidity and hardly any protection from hidden obstacles like rocks and roots.

That’s a downside or a boon, however, depending on your preferences. Folks who don’t want to put a whole lot of thought into foot placement might want a more protective shoe and even one with a rock plate, whereas folks familiar with minimalist footwear will feel right at home in the Acceleritas8 RB9X.

Icebug Acceleritas8 RB9X medial view

A medial view of the Icebug Acceleritas8 RB9X.

Icebug Acceleritas8 RB9X Outsole

The outsole of the Icebug Acceleritas8 RB9X is uniquely modeled after the tread design of a tractor tire, where lugs are aligned and angled to channel mud to the outside. By contrast, many other trail running shoes designed for running in mud have big square cleat-like lugs or large chevron-shaped lugs. The lugs on the forefoot of the Acceleritas8 RB9X are set at a roughly 40-degree angle, radiating out from the center of the shoe toward the front to form a forward-facing V.

The heel of the shoe is just the opposite, with lugs angled from the center of the shoe toward the rear creating a rear-facing V. We can’t be sure that this design is markedly better than other tread designs, but, according to our testers, it certainly works. The large channels between lugs along with the overall flexibility of the shoe seem to allow mud to readily fall right off the outsole.

“I never knew one of the missing pieces in my life was the ability to turn my bare feet into tractor wheels,” one tester said. “One of the hills I ascended slanted like a Sisyphean mud slide daring me to even try to go up without slipping down again and again, but the shoes clung to the hillside with a mountaineer’s fortitude, and I was up and over in one go.

Icebug Acceleritas8 RB9X outsole

The outsole of the Icebug Acceleritas8 RB9X.

Icebug Acceleritas8 RB9X Overall Impressions

“I’m giving the Icebug Acceleritas8 RB9X 10s across the board because I am in love,” one of our testers enthusiastically wrote. “Comfortable straight out of the box, when I put them on my feet, I felt like a dog whose person just grabbed a leash — ready to go!” She found the Acceleritas8 RB9X to grip in slippery mud, dash confidently through the dry trail, and transform “Chitty Chitty Bang Bang style into water vessels through puddle ponds.”

Our less enthusiastic testers had to agree on all points, really only knocking the minimalism of this shoe, while also realizing that the minimalism is probably the thing that will make people choose this shoe over its bulkier and stiffer mud-running shoe competitors.

So, if you run in minimalist footwear and have already worked through all the calf and tendon strains of barefoot style and want a mud shoe to add to your quiver, the Icebug Acceleritas8 RB9X is one we would recommend. To learn more, check out our best trail running shoes for mud guide, where we named this shoe one of the best mud-specific shoes.

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Call for Comments

  • Would you consider the Icebug Acceleritas8 RB9X a minimalist shoe?
  • Do you prefer minimal shoes for mud running?

[Editor’s Note: If you’re affiliated (i.e., an employee, ambassador, etc.) with a brand, please share your relation in each of your comments on this article. Thanks!]

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Icebug Acceleritas8 RB9X upper

A top view of the Icebug Acceleritas8 RB9X.

Ben Kilbourne

Ben Kilbourne is a Gear Tester, Writer, and Editor at iRunFar. He’s been writing about ultralight backpacking and fastpacking, as well as the intersection of these types of recreation with environmental issues for four years. Aside from iRunFar, he has written for publications including Backpacker Magazine, Backpacking Light, Dark Mountain, and Section Hiker. Based in Salt Lake City, Utah, Ben explores all over the west, but especially the canyon country of the Colorado Plateau. His experiences on the land, whether triumphant or thwarted by events either in or out of his control, have provided the foundation for his essays, paintings, articles, and songs.