Simond MT900 UL 50 Review

Overview

The Simond MT900 UL 50 is a 50.5L roll-top backpack that weighs just 880g — a weight-to-capacity ratio that most 50L packs on the market don’t come close to touching. It’s built by Simond, the century-plus-old French mountaineering brand that Decathlon acquired in 2008 but kept running as a semi-independent technical label, and it’s aimed squarely at long-distance trekkers and thru-hikers who are counting grams but still want a real back system, not just a stuffsack with straps.

Key Specs

Spec	Value
Weight	880 g
Volume	50.5 L (expandable via roll-top + compression)
Material	100D Ripstop Polyamide
Closure	Roll-top
Hydration compatibility	2L bladder sleeve
Max recommended load	12 kg
Warranty	10 years

Performance

The headline number here is genuinely the story: one reviewer who put the pack through both day hikes and multi-day treks pointed out that lightness is the most striking feature setting this pack apart, since typical trekking packs run a weight-to-capacity ratio of 30-35 grams per liter while the MT900 comes in around 17.6. That’s not marketing spin — Simond apparently spent real R&D time chasing it, with one write-up noting the pack reportedly took three years of research and testing to develop, with a goal of hitting 880 grams for a 50L capacity without giving up durability and functionality.

Where does that weight actually get shaved? Mostly from the closure and frame. This is a roll-top, not a lid-and-brain setup, and it uses a roll-top closure rather than a proper lid, though you still get a hydration pouch sleeve, a steel frame, a proper back panel and multiple pockets for storage. The volume itself flexes a bit — the volume, varying from 50 to 55 L, can be adjusted using the roll-top closure and the compression cords that wrap around it, which is handy for dialing in bulk on multi-day food carries versus a fastpacking loadout.

Back panel comfort is the pack’s other strong suit, and it’s the part that surprised testers most given the weight. One reviewer called out the back panel as their favorite feature, noting the suspended mesh, supported by an ultra-light alloy frame, provides good support and effective ventilation between the backpack and the back, and breathability proved excellent even during high-intensity activity without compromising load stability. The shoulder straps follow the same logic — thin doesn’t mean uncomfortable here, since the shoulder straps are comfortable despite being quite thin, thanks to the double-density foam, a detail echoed by Simond’s own award writeup describing shoulder straps and hip belt made with double-density foam to ensure stability and comfort, even on long tours.

The catch — and it’s a real one, not a nitpick — is load limits. This pack is not trying to be a mule. Testers were consistent that the waist belt has a very light structure and offers reduced support in distributing weight on the hips, so the minimalist materials don’t recommend loads exceeding 10-12 kg. That lines up with the 12kg max-recommended-load spec. If you’re the type who packs a 15+ kg bear-canister winter loadout, this isn’t your pack; if you’re running a sub-9kg base weight thru-hiking kit with food and water on top, it’s right in its comfort zone. One long-term tester specifically ran it with loads between 7 and 11 kg across day trips and multi-day treks, which is a realistic ultralight range.

Weather protection is a mixed bag. The fabric itself holds up fine day-to-day — it’s made of 100D Ripstop polyamide, a honeycomb-structured fabric that balances lightness with abrasion and tear resistance — but there’s no built-in rain cover, and while the fabric is water-repellent, the backpack doesn’t come with a rain cover, so it’s advisable to protect gear with internal waterproof bags or buy a cover separately when hiking in wet conditions. Budget for a liner bag or cover if you’re headed somewhere like the PNW or Scotland.

On the durability question — always the first worry with anything this light — Simond says the pack went through serious abuse testing before release, including a ‘Jerk Test’ simulating 10,000 sudden drops of a fully-loaded bag to test the fabrics and construction, and the brand claims it was tested for real on the Pacific Crest Trail, covering around 4240km over five months. That’s brand-supplied testing rather than independent long-term data, so treat it as a good sign rather than proof — I’d still want to see more owner reports after a full thru-hike season before calling durability settled.

Pros & Cons

Pros

• Genuinely class-leading weight for the capacity (880g for 50.5L)
• Ventilated, suspended mesh back panel that performs well even loaded and moving fast
• Comfortable straps and hip belt foam despite minimal bulk
• Roll-top gives flexible volume between 50-55L
• 10-year warranty is unusually generous for an ultralight pack
• 2L hydration sleeve included

Cons

• 12kg max recommended load — not for heavier winter or bear-can setups
• Hip belt has minimal structure, so weight transfer to the hips is limited under heavier loads
• No included rain cover, and the fabric is only water-repellent, not waterproof
• Roll-top closure means no quick-grab lid pocket
• Still a relatively new design — long-term durability data from owners is thin

Who Should Buy This

This pack makes the most sense for thru-hikers and long-distance trekkers who’ve already dialed in a lightweight kit — think sub-9kg base weight — and want a 50L pack that won’t undo their gram-counting. It’s a good match for routes like the PCT, GR20, or Camino de Santiago where you’re moving big miles day after day and comfort under moderate loads matters more than raw carrying capacity. If your loadout regularly pushes past 12-13kg — extra layers, a bear canister, technical climbing gear — you’ll want a pack with a more substantial hip belt and frame instead.

Verdict

The MT900 UL 50 delivers on its core promise: a 50L pack at 880g that’s still genuinely comfortable to wear, thanks to a well-executed back panel and foam straps. The trade-off is a soft hip belt and a firm 12kg practical ceiling, so this is a pack for disciplined ultralight packers, not one to grow into. For the right user, it’s one of the more compelling weight-to-comfort ratios currently on the market — I’d rate it 7.5/10, with the extra half-point held back until more owners have put it through a full season of abuse.