Allbirds Trail Runners SWT 

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Allbirds entered the footwear business less than a decade ago and have enjoyed remarkable growth and success since their initial launch. The company was founded on a number of guiding principles focused on sustainability and social responsibility, with their shoes featuring extensive utilization of wool fibers and naturally sourced materials over synthetics whenever possible. These materials come from a small number of suppliers who also commit to the same standards of environmental and labor-related practices.

The Allbirds product line has historically been focused on casual and athleisure-type footwear, however, they’ve recently expanded into high-demand athletic use. The Trail Runner SWT (sugar, wool and tree – the shoe’s primary source materials) is their first model built specifically for trail running. Allbirds claims the shoe was tested for over 2,000 miles by 100 runners and hikers in the company’s Allgood Collective roster, which includes ultrarunner Jorge Maravilla. Despite this, we were a bit skeptical of the shoe’s long-term durability at first glance, so we racked up a few more miles than usual with the SWTs before writing up a review. So far, we’ve put more than 250 miles on each of our test pairs, and their durability has been quite impressive. That’s not to say they are perfect, but the SWT is a strong debut into the trail space.

Wool mesh upper with rounded forefoot

True to the company’s material construction ethos, naturally sourced materials are used throughout the SWT, starting with uppers that are made from a blend of merino wool and Forest Stewardship Council (FSC) certified Tencel Lyocell eucalyptus tree fiber. There is no tongue on the upper, just a soft bootie that stretches for foot entry and has a slipper-like feel against the top of the foot. The merino wool is extremely comfortable and breathes better than expected during hot weather but is extremely slow to dry when saturated. You can easily go sockless in these shoes, thanks to the comfort of the wool liner plus the elasticized ankle collar that keeps out the grit. The fabric is also very flexible and doesn’t cause irritation or hot spots, even on runs of 20+ miles. Fit through the rearfoot is comfortable and secure with moderate ankle padding, while the forefoot last is rounded enough to accommodate toe splay on longer runs.

Soft interior lining with moderate ankle padding

An external lacing system is anchored into a tall ripstop overlay of merino wool and recycled polyester to keep the foot secure. The laces are probably thicker than any you’ve seen on other models of trail shoes, but the system works really well to provide a secure fit without excess pressure on the top of the foot. The tall overlays provide great protection and durability, but they tend to run hot. They also contribute to the overall weight of the shoe, which will be a recurring theme here.

Eyelets anchored to external overlays

Allbirds Trail Runners SWT women’s

Perhaps the most interesting construction element of the SWT is the midsole compound, called SweetFoam, because it is derived from sugarcane rather than oil-based materials. The ride quality is surprisingly good, with a firm overall feel; its cushioning and energy return aren’t dramatic, but they aren’t lacking either. A 7mm heel-to-toe drop favors heel strikers but can also accommodate midfoot strikers. The SweetFoam compound provides a smooth, consistent ride, and the density of the material eliminates the need for rock plates or other synthetic enhancements. However, this density has the side effect of being noticeably heavy; the spec weight of the Trail Runner SWT is 12.38oz, and the midsole compound is clearly the primary driver, considering that the stack heights are not particularly tall.

MTB-inspired outsole lugging

Traction on the SWT comes from an FSC-certified natural rubber outsole compound cut into 4mm lugs. They eschew the traditional geometric triangle, diamond or chevron shapes of most lugs in favor of rounded multi-directional curves that overlap and interact with each other like the tread of a mountain bike. The curves are also inspired by the art of English pop artist David Hockney (Google “David Hockney pool patterns” to see what we mean) and are unlike any other outsole we’ve seen. More importantly, they are extremely good at maintaining grip in a variety of conditions. We tested this shoe from the heat of late summer through the autumn downpours of a West Coast atmospheric river, and traction from the SWT outsole was equally solid on dry, loose gravel and thick, sloppy mud. We’ve also used it for hybrid road-to-trail runs; the ride quality on asphalt is similar to the dirt, and the lug heights of the outsole have a better than average wear rate compared to many other outsoles we’ve tested.

For a debut model, the Allbirds Trail Runner SWT offers a number of design and performance elements that already put it on equal footing with established brands. On a larger scale, the addition of Allbirds to the performance footwear category promises to push the industry towards more natural, sustainable and responsible manufacturing practices, which is great news. However, the weight of this shoe is a clear Achilles heel that will hopefully be addressed in future versions; at more than 12oz, the shoe exacerbates leg fatigue on long runs and doesn’t facilitate fast running during shorter sessions. If this shoe was a few ounces lighter, we wouldn’t hesitate to wear it for long training days or races, but as it is now, it’s best for routine base mileage or recreational use. Even with that caveat, we were pleasantly surprised at how much we enjoyed wearing the SWT, and we look forward to future evolutions from Allbirds.

The Allbirds Trail Runner SWT is available in men’s and women’s versions at www.allbirds.com.

Features and Specs:

●   Weight (men’s/women’s, average among size range): 12.36oz
●   Stack height (heel/toe, in mm): 25/18
●   Heel-toe drop (mm): 7mm
●   Upper: Tencel Lyocell (eucalyptus tree fiber) and merino wool blend upper with recycled polyester ripstop reinforcement
●   Midsole: SweetFoam EVA compound derived from sugarcane
●   Outsole: FSC-certified natural rubber with multi-directional 4mm lugs
●   MSRP: $138