Salomon S/LAB Phantasm 3 Review: An Aerodynamic Advantage?

Salomon has long been synonymous with trail running. But since the launch of the Sonic line in 2016, the brand has expanded its focus to include the road. Salomon’s latest and most ambitious road project yet is an updated version of its carbon-fiber super shoe, the S/LAB Phantasm. Rather than chasing marginal gains through foam or plate tweaks, Salomon turned to one of the under-explored variables in super-shoe performance: aerodynamics.

Taking a page out of the cycling innovation playbook, Salomon turned to the wind tunnel to optimize this overlooked variable in running. We found out where they focused to improve the shoe’s aerodynamics, and put a pre-release sample to the test.

Salomon S/Lab Phantasm 3 At-a-Glance

Salomon S/Lab Phantasm 3

Weight: 7.0 oz (men’s 9, women’s 10.5)
Stack Height: 39.5–33.5 mm
Heel-to-toe Drop: 6 mm

Pros and Cons

+ Incredibly smooth-riding midsole
+ Provides excellent cushioning without being mushy
+ Head-turning futuristic design

– Difficult to get on and tie the laces
– Narrow width under the heel is not ideal for heel strikers

The S Curve of Super Shoe Innovation

New technologies often follow a pattern known as the S-curve of innovation in which they progress slowly at first, accelerate rapidly, then plateau as further gains become harder to achieve. Super shoes now appear to be entering that final stage.

Today, nearly ten years after the first super shoe was created, the fundamental materials and design (foam, plate, and midsole geometry) are largely understood and optimized, making meaningful progress difficult. To find marginal gains in performance and stand out from an increasingly homogenous field of super shoes, brands are looking beyond refining the fundamentals.

Aerodynamics and Running

During a run in 2023, Gatien Airiau, Product Line Manager for Road Running Footwear at Salomon, was discussing the future of road running shoes with a colleague. The conversation turned to aerodynamics, which led to a cycling company called Swiss Side, best known for wind-tunnel testing and aerodynamic consulting in professional cycling. Shortly thereafter, Airiau met with the Swiss Side founder, Jean-Paul Ballard, to explore how they could work together to improve shoes.

Aerodynamics has already been explored in running apparel and pacing. Nike’s AeroSwift gear, worn by Faith Kipyegon during her sub-4-minute mile attempt, and Eliud Kipchoge’s wind tunnel-tested drafting strategy in the Breaking2 project, showed that aerodynamics had the opportunity to enhance performance. Yet, despite its influence on clothing and race tactics, aerodynamics has remained largely unexplored in the realm of footwear.

To explore the potential benefits, Airiau and his team conducted a study to quantify what performance gains could be achieved. They tested 12 shoes, ranging from the chunky Hoka Bondi to the sleek Nike Vaporfly, on a treadmill. They found that a runner’s foot speed during the forward swing of the stride is twice their pace. At those speeds, shoe drag becomes more significant, suggesting the potential of performance gains by optimizing a shoe’s aerodynamic efficiency.

Inside the Wind Tunnel

Using a compact two-by-two-meter wind tunnel to evaluate various shoe shapes, the team fixed each shoe at the 50-degree and 25-degree angles of a runner’s gait. They 3D-printed over 80 prototypes with different design modifications and tested them in the compact tunnel. Using computational fluid dynamics, they determined that the biggest areas where aerodynamic efficiency could be improved were the transitions between the outsole, midsole, and upper.

The more they could smooth out each transition and make the shoe a natural extension of the leg, the better it performed in the compact wind tunnel. The final design featured a rounded, smooth midsole and an integrated upper that covers the laces.

Once the team settled on a final prototype, Salomon, with support from Swiss Side, conducted running economy tests with elite athletes in a large-scale wind tunnel. Athletes completed two 12-minute runs at LT1 pace in the S/LAB Phantasm 2, first without wind and then with a 20 km/h headwind to replicate outdoor conditions. After an eight-minute recovery, the same protocol was repeated in the S/LAB Phantasm 3.

The results backed up what Salomon first saw in the small wind tunnel: the S/LAB Phantasm 3 reduced overall aerodynamic drag by 2.5 to 3 percent, a margin Salomon claims could equate to as much as 18 seconds over a marathon run at 20 km/h (aka 2:06:35 marathon pace). While an independent running economy comparison against competing models would strengthen Salomon’s case, the early data suggests there’s more here than just theory.

The shoe also recently received a compelling real-world demonstration, with ultrarunning super star Courtney Dauwalter bettering her marathon personal best by a massive 11 minutes, posting a 2:38:55 at the California International Marathon while running in them. Futsum Zienasellassie won the men’s race in 2:09:31, also a personal best, in the same shoe.

Salomon S/Lab Phantasm 3: First Impressions

Put to the test on the road, the Phantasm 3 outperforms its predecessor in every way, aerodynamic innovation aside. That was noticeable immediately. It runs like a completely different shoe than the Phantasm 2.

The weight dropped 10 percent to 7 ounces, while the stack height increased by 10 percent to 39.5 millimeters under the heel. It still uses a supercritical PEBA foam, but with a softer, denser formulation. The spoon-shaped carbon fiber plate remains the same.

On the run, I tested the S/Lab Phantasm 3 from an easy warm-up pace to around 5 minutes per mile, and the ride felt remarkably consistent throughout. I never found a pace at which the shoe felt awkward or out of its element.

The first thing I noticed on the run was how smooth the ride was. It’s not an overly bouncy ride that’s somewhat uncontrollable, like some PEBA-based supershoes. I found the foam to be rather stable. However, like the Phantasm 2, the width from the midfoot back to the heel was quite narrow, leading me to question whether the shoe would be stable enough for a rearfoot striker.

The wide forefoot features a noticeable, but moderate, rocker that makes transitions from the heel smooth, without requiring a powerful toe-off like some shoes with a steep rocker do.

The standout feature of the shoe is no doubt the white bootie upper that belies the shoe’s aerodynamics. The outer layer is made of a very thin, light, stretchy material. Inside is a single-layer engineered mesh upper with sawtooth laces. It’s not an easy shoe to get on by any means; getting the internal upper to lie flat takes some patience. Personally, that’s not a downside: I like a racing shoe that’s hard to get on. I don’t wear it often, so it’s not a daily annoyance, and the snug fit makes me feel locked in, ready to roll.

I couldn’t point to a moment when I felt a clear aerodynamic benefit from the shoe, but the enclosed-lace design was noticeable, giving the upper a clean, uninterrupted feel that enhanced the locked-in sensation.

Salomon S/Lab Phantasm 3: Who It’s For

The S/Lab Phantasm 3 is best suited for competitive road runners racing longer distances, whose higher leg speeds create greater aerodynamic drag. I’m skeptical that average or slower runners, with lower leg speeds, will benefit much from the aerodynamic optimization.

More than anything, the S/Lab Phantasm 3 signals how Salomon is approaching shoe design. Rather than chasing trends or copying what already works elsewhere, Salomon is investing in research and testing to guide their development process.

Salomon has been vocal that it wants to increase its road reputation. To be a true player in the road shoe market today, having a legitimate super shoe is a requirement. Salomon wasn’t even on my radar as a super shoe contender before the S/Lab Phantasm 3, but its performance puts the brand in the race, and the aerodynamic tech should turn heads.

Whether aerodynamics ultimately proves to be a meaningful performance lever in super shoes remains an open question. Still, Salomon’s findings with the Phantasm 3, paired with signals from On’s lace-free Cloudboom LightSpray, suggest that smoother, more integrated constructions may play a larger role in the next phase of super shoe design.

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