Allbirds Trail Runner SWT First Runs: An Eco-Friendly Trail Shoe With Trade-Offs

Introduction

Allbirds has made its move from road to trail with the Trail Runner SWT, and we have put a few early first-run miles into it. The headline details: a 7mm drop, a 25mm heel stack and 18mm forefoot, 4mm lugs for traction, and a weight of 369g in a UK men’s size 9 (13 ounces in a US men’s size 10). Pricing sits at £128 or $138.

The key thing to understand before buying is what this shoe is not. It is not a performance trail racer, and Allbirds does not pretend otherwise. It is a casual trail and hiking-running shoe designed for light to rugged trails, wet and dry climates, and distances of roughly five to ten miles. Judged on that brief, it does a reasonable job, but there are real trade-offs to know about first.

Who This Shoe Is For

This is the shoe for the casual trailer: someone who runs a few times a week, occasionally goes off-road around a park or local forest, prefers shorter efforts of 5K to 15K, and wants something friendlier to the planet while doing it. If you chase PBs or plan ultras, this is not your shoe.

Both testers agreed with Allbirds’ own five-to-ten-mile categorization. Beyond that distance, foot fatigue becomes a real risk because the midsole foam does not compress much.

Materials and Design

The eco story is the heart of the shoe. Allbirds has replaced as many petrochemical-based materials as possible with plant-based and natural alternatives, including merino wool and eucalyptus tree fibers, plus a fluorine-free water-repellent coating to keep water out. The laces come from recycled plastic bottles, and the midsole foam is SweetFoam derived from sugar cane. Each pair even carries a stamped carbon footprint of 16.3kg of CO2 under the removable insole.

The one-piece upper construction splits into two zones: a tight-knit merino wool midsection with a soft knitted heel collar, and eucalyptus fiber panels running around the toe box and down the sides for added support. Inside, a merino wool lining holds the heel in place and adds comfort across the top of the foot. A natural rubber outsole and a low, plant-based TPU heel counter round things out.

Fit and Sizing

Fit is worth thinking about carefully. One tester found the shoe quite long in his normal size, with a very spacious toe box that felt more like a regular shoe than a running shoe, and suggested going half a size down. The minimal lacing also makes a proper heel lockdown harder to achieve, though working the laces tight helps.

Interestingly, the other tester ran half a size up from his usual and found the roomy toe box ran fine with no slipping, suggesting some might go half a size up instead. Foot shape clearly matters here, so trying both directions is sensible if you can.

Grip and Ride Feel

Grip on a range of surfaces is genuinely good: hard forest trails, stony sections, sloppy ground, grass, and even tarmac all handled well. The weak point is deep mud, where the unusual lug shape struggles to get purchase and tends to pick up mud, so the shoe skates on the wettest sections.

The ride is firm and bottom-heavy, and the shoe feels heavy in general. It is the opposite end of the scale from big-cushioned modern trail shoes. You will feel stones popping through the sole, but the wide, stable base is a genuine plus. On softer, uneven trail ground, that firmness matters far less than it would on roads.

Buying Advice

If your trail running is short, casual, and easy-paced, and reducing your carbon footprint matters to you, this is a lovely option. The uppers are very comfortable and hug the foot nicely, and easy plods on the trail are genuinely enjoyable in it.

If you care most about the ride and performance, look elsewhere. You are making a trade-off for the eco credentials: heavier weight, firmer foam, and no high-performance intent. We would also like to see the weight come down and the ride soften up in future versions, and merino wool may hold water on wet runs despite the coating.

Conclusion

The Trail Runner SWT runs like an Allbirds shoe: firm, not the highest performing, but honest about what it is. For short runs up to around five miles on lighter, easier trails at a casual pace, it does a good job while pointing the way toward more sustainable materials in the trail space. It is a promising move for the category, and one worth considering if your priorities match its brief.