Salomon S/Lab Ultra 2in1 Shorts Review: The Ultra-Trail Benchmark

The S/Lab Ultra 2in1 is the pair of shorts Salomon reserves for its top team. D'Haene, Mathys and Engdahl race in it. On paper: an inner compression liner with a hexagonal pattern, a 360° storage waistband with three mesh pockets, and an ultra-breathable, laser-perforated outer short. On the trail: one of the few trail shorts that can go 24 hours without chafing. Full review after 600 km of long runs.

Salomon S/Lab Ultra 2in1: the shorts Salomon's elite runners wear

The S/Lab Ultra 2in1 was built to a precise brief: equip François D'Haene, Adrien Mathys and Eli Engdahl for races lasting more than 20 hours. The result is a pair of shorts at €130 (sometimes €145 depending on the French retailer) that combines two pieces in one: an ultra-breathable, laser-perforated outer short and a hexagonal-pattern compression liner that covers the zone where chafing starts. For 2026, Salomon has locked in the design with the Active Fit cut and the 360° storage waistband with three pockets. There is no adjustable drawcord in the lineup, and that remains the model's sore spot.

RunMorph's advice. At RunMorph, we see the S/Lab Ultra 2in1 as the investment to make if you run beyond 6 hours and have already dealt with thigh chafing in an ultra. For shorter runs, a regular 1-in-1 trail short does the job just fine. Pair it with a running pack built for quick access, such as the NNormal Race Vest 5L or the Ultimate Direction Race Vest 6L, whose back pockets work well alongside the shorts' flask-carrying waistband.

© Salomon, official photo used for editorial purposes

Objective technical data

Who is the S/Lab Ultra 2in1 for?

Ultrarunners racing 80 km and beyond

This is the core target. The hexagonal-pattern inner liner was designed for repeated thigh-on-thigh friction over 100 km and more. If you're training for UTMB, the Diagonale des Fous, TDS, the Madeira Island Ultra-Trail or the Grand Raid des Pyrénées, this is one of the few shorts on the market that holds up without incident past the 15th hour.

Runners who have already suffered chafing in a race

If you've ever limped across a finish line with raw inner thighs, these shorts solve 90% of the problem. The body-mapped compression holds your muscles without slipping, and the hexagonal pattern creates micro-ventilation that limits moisture buildup. The smart move: test these shorts on a long run of at least 4 to 5 hours before you race in them.

Competitive trail runners on training long runs

If you log 2 long runs a week of 2 hr 30 min to 4 hours, the S/Lab Ultra 2in1 works as a mini lab. The 360° waistband holds two 250 ml soft flasks and enough food for 3 hours of effort, so you can leave the vest at home on loop sessions.

Comfort, fit, feel

The Active Fit cut is snug but not tight. The outer short falls freely at 5 inches (12-13 cm) above the knee, and the inner liner extends to 7 inches (17-18 cm). That 2-inch difference is deliberate: the outer short moves with your stride while the liner stays put. If you normally wear M in road running shorts, take M here too.

The feel on the skin is instantly recognizable. The compression is firm without being stifling, and the liner's hexagonal pattern feels like a light massage on the run. The fabric dries very fast: 15 minutes in the sun after a river crossing is enough to get it nearly dry. In the rain, the DWR keeps the outer short from getting heavy.

The friction point (literally and figuratively) is still the waistband with no adjustable drawcord. In a well-sized pair, it stays put. In a slightly large pair, it slips on descents, especially if you load the back pockets with a phone. International reviewers have flagged this flaw for 2 seasons and it still hasn't been fixed. Keep this in mind if you're between two sizes: size down.

On the trail

Tested over 5 long runs of 3 to 5 hours in the Vercors, plus 1 self-supported 80 km ultra. No chafing to report on the inner thigh, even in the heat (28°C, 70% humidity). The inner liner delivers on its promise: compression without suffocation.

The storage waistband works well with its side and back pockets, which take a 250 ml soft flask on each side plus a compact smartphone. The zippered center back pocket is ideal for keys. Don't overload it, though: beyond 400 g spread across the waistband, the shorts start to sag, and the Active Fit cut can no longer hold them up.

Quick drying is probably the most underrated strength. On a self-supported run with spring-water refills, you can rinse off in a mountain stream, run 10 minutes at a moderate pace and set off dry again. That's a major psychological comfort in races that last 20 hours.

Pockets and technical details

© Salomon, official photo used for editorial purposes

The 360° waistband is wide (about 8 cm) and has three mesh compartments: two side pockets that each take a 250 ml soft flask or a phone, plus a deeper zippered center back pocket for keys or an ID card. The open mesh lets your lower back breathe, which avoids the moisture buildup typical of standard running belts.

The hexagonal-pattern inner liner is the centerpiece. The hexagons aren't decorative: they create raised micro-zones that lift the fabric off the skin over 30% of the surface, limiting moisture buildup and sweat-driven friction. It's a technology found in some high-end cycling shorts, applied here to trail running.

The hems are fully bonded, with no protruding seams. That's what lets the shorts go past the 12th hour without irritation. The detail that changes everything: no sharp edge against the skin in the crease zones.

How it stacks up against the competition

In the 2-in-1 trail racing shorts segment above €100, the S/Lab Ultra faces high-end competition.

Versus Compressport Trail Racing Short V2 (155 g, €110). The Compressport goes for stronger full-length compression but has no dedicated inner liner. Edge to Compressport for pure muscle support, edge to the S/Lab Ultra for chafing management over long distances.

Versus Hoka Glide Short Tights (140 g, €95). The Hoka is less technical but more affordable. Edge to Hoka for use 2 times a week over medium distances, edge to the S/Lab Ultra for ultra-trail racing.

Versus Patagonia Strider Pro 5-inch (100 g, €95). The Patagonia is lighter and more breathable, but has no 2-in-1 liner. Edge to Patagonia for short races in the heat, edge to the S/Lab Ultra once you go past 6 hours of effort.

To pair it with a pack, look at the NNormal Race Vest 5L or the Osprey Duro 6. The shorts' storage waistband and the vest's front pockets don't overlap.

How to fit it into your RunMorph training plan

The S/Lab Ultra 2in1 isn't an everyday pair of shorts. It's built for long runs and races. Here's how to use it within a RunMorph training plan cycle:

• Training for an ultra (80 km and beyond), wear the shorts on 4 long runs of 3 to 5 hours in the 8 weeks before the race. You confirm there's no chafing and dial in how you load the waistband pockets.
• Training for a 30-50 km trail race, take the shorts out for 2 to 3 race-simulation runs. The rest of the time, a regular 1-in-1 short is enough.
• Training for a road marathon, forget it. The outer short is too thick for the road and you don't need a compression liner for 3 hours of effort.

A habit worth building: wash the shorts inside out, air-dry them, no tumble dryer. The compression fabric and the waistband mesh can't handle the heat of a home dryer.

© Salomon, official photo used for editorial purposes

RunMorph verdict

As of June 2026, the S/Lab Ultra 2in1 is the most polished trail short in the ultra-distance segment. Not the lightest. Not the most affordable. But the one that goes past the 15th hour without irritation, which is exactly what you ask of an ultra short. The 360° waistband changes how you use it: you can head out for 3 hours fully self-supported without a vest, which changes the dynamic of your training runs.

The lack of a drawcord remains the weak spot, and it's no small detail. On €130 shorts, we would have liked Salomon to fix this flaw at some point over the past 2 seasons. RunMorph score: 8/10. One point off for the missing adjustable drawcord, half a point off for the price against non-2in1 competitors.

© Salomon, official photo used for editorial purposes

Key takeaways for your training

• The S/Lab Ultra 2in1 is a racing investment, not a do-it-all short. Keep a regular 1-in-1 short for shorter weekday runs.
• If you're between two sizes, size down. With no drawcord, the waistband has to fit right.
• Test the shorts on at least 4 long runs before racing in them. The compression takes a few hours to show what it can do.
• Keep the waistband load to 400 g maximum. Beyond that, the shorts sag.
• Wash inside out, air-dry, never tumble-dry. The life of the compression fabric depends on it.