Ultralight vs. Traditional Backpacks: A Field Test to Unravel Load-Carrying Performance

Published February 27, 2026 02:15PM

For decades, the paradigm for backpackers tasked with carrying substantial loads – think week-long expeditions or full-winter camping setups – has been the robust, internal-frame pack. These behemoths, built with sturdy frames and ample padding, were the undisputed champions of heavy-duty hauling. However, the landscape of outdoor gear is in constant flux, and a new contender has emerged from the shadows of the ultralight movement. Recent testing at the esteemed Outside Lab at CU Denver has revealed a surprising development: a select few modern ultralight packs are now demonstrating the ability to distribute significant weight as efficiently as their considerably heavier, traditional counterparts. This lab-based revelation, where weight transfer to the hip belt was measured to be on par with established models, naturally begs the critical question: do these promising laboratory results translate to the unpredictable realities of the trail?

To bridge the gap between controlled scientific measurement and the nuanced experience of human physiology, a novel approach was undertaken. Since test dummies, however sophisticated, cannot articulate the subtle sensations of carrying a loaded pack, two willing human participants were enlisted: Adam Roy, Editor-in-Chief of Backpacker, and Adam Trenkamp, Outside Lab Test Editor. Their mission was to conduct a direct, side-by-side comparison of a traditional pack and a cutting-edge ultralight model, both subjected to identical loads, to ascertain how their lab-tested capacities would manifest in real-world performance. The packs chosen for this critical evaluation were the Gregory Paragon, a representative of the traditional backpacking pack design, and the Zpacks Arc Haul 60, a leading example of the ultralight philosophy. The core of the investigation lay in determining if the lab’s findings—that both packs could handle the same weight before reaching their failure point—would translate to a comparable user experience on varied terrain.

In an interview format that underscores the practical application of lab data, Adam Trenkamp elaborated on the lab’s capabilities and limitations. "Here in the lab," Trenkamp explained, "we can meticulously measure how much weight each pack can carry and determine its ultimate failure point. We use mannequins for this, which allows for precise, repeatable testing. However, what a mannequin cannot convey is the subjective feeling of carrying that weight. The way the load shifts as you move, the pressure points, the overall comfort – these are crucial aspects that can only be truly understood through human subjects interacting with the gear in its intended environment." This sentiment was echoed by Adam Roy, who expressed his eagerness to serve as the "dummy" for this crucial field test, acknowledging that such a role has been a part of his professional journey before.

The selected packs, the Gregory Paragon and the Zpacks Arc Haul 60, were chosen specifically because their lab tests indicated they reached their failure point at the same weight. This crucial data point set the stage for the comparison, suggesting a theoretical parity in load-carrying capacity. However, both editors recognized that weight capacity is only one facet of a pack’s performance. "There are numerous factors that influence how a pack actually feels on your back," Trenkamp noted, "factors that a simple lab test with a mannequin simply cannot capture." These unquantifiable elements, such as the dynamics of weight distribution during movement, the effectiveness of suspension systems on uneven terrain, and the impact of load bulge, are precisely what the field test aimed to illuminate.

Trenkamp further detailed the testing methodology, outlining a plan to load each pack to what was determined in the lab to be within the "middle of their comfort range." This specific load point, approximately 30-35% of the pack’s load capacity on the shoulders, was chosen to be slightly above what is considered purely comfortable, but not so heavy as to be overwhelming. The objective was to create a scenario where subtle differences in weight transfer, stability, and overall feel would become readily apparent. "We want to be able to feel the weight shifting around," Trenkamp stated, "but we don’t want to be so overwhelmed by the load that we can’t discern the nuances of each pack’s performance."

To ensure a realistic simulation of a backpacking scenario, the packs were filled with a combination of common backcountry items. This included sleeping bags and sleeping pads to fill the volume of the packs, creating a more natural load distribution. Crucially, dumbbells were also incorporated into the load. This deliberate addition served a dual purpose: to contribute to the overall weight and to simulate the impact of dense, potentially awkward items that can affect a pack’s balance and stability. The total weight for each pack was carefully calibrated to 44 pounds, 1 ounce for one and 44 pounds, 10 ounces for the other, a negligible difference that ensured a fair comparison. The inclusion of dumbbells, humorously framed by Roy as essential for maintaining upper body strength on the trail, highlighted the practical considerations of gear selection and the need for packs to manage a variety of load types effectively.

The first leg of the field test involved each editor donning one of the loaded packs and embarking on a walk around the building and its surrounding grounds. This initial phase was designed to provide immediate feedback on the immediate feel of the packs. Adam Trenkamp, wearing the Zpacks Arc Haul 60, described his experience: "Load-wise, I can feel that it’s really just that external sort of frame stay and like small frame. I can feel things pushing into my back a little bit more, which is not necessarily weight uncomfortable on my shoulders, but it is a little bit more uncomfortable on my back itself." He characterized his experience with the ultralight pack as akin to being in an F1 race car – built for speed and performance, but not necessarily for plush comfort.

Conversely, Adam Roy, wearing the Gregory Paragon, offered a contrasting perspective: "What I’ve got on right now feels like the equivalent of a luxury car. Like maybe it’s not as high performance as the pack you have, maybe it’s not trimmed down to every ounce, but it’s padded, it’s contoured to my body really well. Right now it’s fairly comfortable for all the weight it’s carrying." He emphasized the pack’s well-padded and contoured design, which contributed to a sense of comfort despite the significant load. This analogy effectively captured the perceived difference in design philosophy – one prioritizing minimalist efficiency, the other emphasizing user comfort through more substantial construction.

The conversation then turned to the suspension systems of the packs. Trenkamp noted that while the Zpacks Arc Haul 60 felt stable enough on a flat surface, he anticipated potential challenges on more undulating terrain. Roy, on the other hand, praised the Gregory Paragon’s suspension: "The suspension on this pack is actually quite nice. I don’t feel it shifting basically at all when I’m moving side to side, feels rock solid. Feels a little springy almost, which could be the back panel, but it’s absorbing some of the energy when I step, you know, the kind of rocking back and forth isn’t… I could see it, you know, being more comfortable over the long run instead of causing wear on my back." This observation pointed to the potential long-term benefits of a well-engineered suspension system in mitigating fatigue and discomfort.

A direct inquiry into how the weight felt on their shoulders and hips revealed further distinctions. Roy, still wearing the Gregory Paragon, reported feeling some strain on his shoulders, despite the hip belt carrying the majority of the load. He speculated that while padding offers short-term comfort, the fundamental forces of carrying a heavy load would eventually lead to soreness. Trenkamp, meanwhile, expressed envy for Roy’s "luxury car," suggesting that the ultralight pack, while potentially lighter in empty weight, was not offering the same level of comfort under load.

The editors then switched packs to experience the performance of the other model. Roy, now wearing the Zpacks Arc Haul 60, immediately noticed a significant difference. "Off the bat I’m noticing a difference," he stated. "This pack is a lot less stable with this weight in it. I’m feeling the shift side to side." He described the ultralight pack’s trampoline-like back panel as feeling more "notional than anything" at this load, and experienced discomfort from the bear canister pushing against his back, an issue he did not encounter with the Gregory Paragon. Roy concluded that on uneven terrain, he would feel more sure-footed with the sturdier, traditional pack.

Trenkamp, after switching to the Gregory Paragon, found the load distribution on his shoulders and hips to feel similar to the Zpacks Arc Haul 60. However, he agreed that the overall comfort and stability of the traditional pack were superior. "I’m not really feeling anything push in my back," he reported. "All I really feel is that suspension pack, a little bit of the foam. It’s pretty comfortable." While acknowledging that both packs were manageable, he leaned towards the traditional pack for its perceived stability on varied terrain.

This direct comparison underscored the critical importance of field testing. "And this is why we do field testing in addition to lab testing, right?" Trenkamp posed rhetorically. "You’re not going to get this kind of information putting it on a mannequin in the lab. You have to move with it and see how it moves." He elaborated that while lab tests are invaluable for understanding load distribution and weight capacity, they cannot replicate the dynamic interaction between the pack, the wearer, and the environment. The subtle shifts in weight, the impact of load bulge, and the direct physical feedback are all elements that necessitate real-world assessment.

The editors then proceeded to climb stairs, simulating an uphill movement. Roy observed, "Actually it’s impressive the difference between these two." He reiterated that while lab data might suggest parity, the reality of comfort and stability revealed significant distinctions. The decision of which pack is "better" ultimately depends on a variety of factors, including the type of terrain, the necessity of carrying specific items like bear canisters, and individual preferences for comfort versus minimalist design.

Trenkamp concluded that the choice between an ultralight and a traditional pack, especially when carrying heavy loads, is not a simple matter of weight. "It may come down to what’s the trail you’re going to be on? Is it going to be a smoother trail that maybe just rolls or is it going to be something with a lot of off-balance steps? Do you have to carry a bear can or not? Those can kind of all kind of influence what type of pack you want to carry." This nuanced perspective emphasizes that the optimal gear choice is highly situational and depends on a thorough understanding of one’s intended use. The adage, "The more we test, the more you know," as championed by the Outside Lab team, serves as a guiding principle in navigating the complex world of outdoor gear, ensuring that consumers can make informed decisions based on both rigorous scientific data and practical, real-world experience.