Symbiosis Gear Thinks Women Deserve Better Ultralight Backpacks

When she was thru-hiking the Pacific Crest Trail, Sarah Berkeley blew through three different packs before coming to a realization: ultralight packs are made for men. A few years later, when she decided that designing her own backpack would be easier than finding the perfect fit off the shelf, she surveyed hundreds of women about what they wanted in a pack. The most common request was simple: shoulder straps that didn’t squish their chest. Today, Berkeley runs Symbiosis Gear, the rare woman-owned ultralight brand. Her flagship product, the Aspen, is a frameless pack designed to fit women and femme bodies.

It’s been a long time since the days of male-dominated hiking and backpacking. According to the Outdoor Industry Association, there’s a roughly 50/50 split between men and women who day hike, and thru-hiker surveys show that women account for about 30 to 40 percent of long-distance backpackers. By and large, the outdoor industry has become more equitable in response. Sizing options for gear have expanded rapidly, and the “pink it and shrink it” trend that disguised ill-fitting men’s gear as women-specific is giving way to intentional design.

But if there’s one niche of the backpacking world that hasn’t caught up, it’s the ultralight community. The stereotypical ultralighter is young, male, and white. The vast majority of ultralight brands are founded by men. Size and fit options for gear still tend to reflect that, though there are a few exceptions. Brands with women founders or co-founders include Toaks, apparel maker Alpine Fit, and Wild Brush, a one-woman cottage operation that Backpacker profiled in 2024.

There’s still a long way to go. To Berkeley, there’s no clearer example of this phenomenon than the ultralight backpack. “I think a lot of women feel excluded,” she says. “Ultralight packs have been designed by men and made for men.” The result is a self-fulfilling cycle. Women say that ultralight gear isn’t designed with them in mind, and look elsewhere for gear. Brands, with few female-identifying customers to cater to, don’t design their products with them in mind. With the Aspen, a frameless pack designed from the ground up exclusively for women, Berkeley hopes to break that cycle.

In designing the pack, Berkeley’s first priority was to dial-in the shoulder strap system. An S-shaped strap helps to accommodate narrower shoulders while also providing extra room around the chest. S-shaped straps aren’t new, but Berkeley says the curves of the Aspen’s shoulder straps are more pronounced, and therefore a better fit for women with larger busts. An elastic sternum strap with three adjustment points (two separate daisy chains run the entire length of each strap) ensures the straps fit as many body shapes and sizes as possible.

Even with the fit figured out, Berkeley soon realized that building a brand focused on ultralight gear for women comes with a big challenge: finding an audience.

“I kind of had the vision of being the Pa’lante Packs for girls,” she says, referencing the cottage pack maker that found success by leveraging word-of-mouth among thru-hikers and ultralight Reddit posters. “What I learned is that a lot of women aren’t ultralight, and not only that, they’re put off by the label. When I talked about making ultralight packs, I encountered some resistance that I didn’t know was there.”

Even though she considers herself an ultralighter, she didn’t think she’d win over the audience she needed to reach by focusing on ounce-cutting features and high-tech fabrics. Nor did she expect the ultralight community—very online and very male—to provide the kind of grassroots hype-building that other ultralight brands benefit from.

Instead, she’s taken a different approach. For one, her messaging to potential customers revolves around simplicity, minimalism, and comfort, rather than “going ultralight.” Because of that, she’s already attracting a wider customer base—not just ultralighters and thru-hikers, but day hikers, peak-baggers, and travelers. She’s also upending the direct-to-consumer sales model that most ultralight brands favor to stay lean and increase margins, and searching out wholesalers and retailers. Even though Symbiosis Gear’s sales currently number in the hundreds, rather than the thousands, the Aspen is already available in 16 retail stores in the US. In comparison, ultralight mainstay ULA lists just 12 US retailers for its products. Most fledgling ultralight brands opt out of the retail side altogether.

The design of the Aspen itself also reflects Berkeley’s search for wider appeal. At 25 ounces, it’s fairly stout for an ultralight pack, with 420-denier Extreema nylon used throughout. There’s also a full mesh back panel and a UHMWPE mesh front pocket, which add weight but also durability and comfort. Extra gear loops, a stretch bottom pocket, and oversized side pockets are designed to make the Aspen as versatile as possible.

This year, Berkeley is focused on expanding the product line. Upcoming releases include a larger, framed pack and more sizing options for the Aspen. The most recent drop is a combination hipbelt pocket/sling bag that she has christened the Huckleberry. Long-term, Berkeley isn’t entirely sure where the brand is heading. Double down on ultralight packs? Or embrace a wider audience with more traditional gear?

“I’m building this very organically and seeing how people respond,” Berkeley says. “Whatever comes next, it starts by listening to women.”