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Black Diamond Speed 40 vs Decathlon Forclaz MT900 UL 50+10L

Weight and specs compared for 2026 — and which one to choose.

Black Diamond Speed 40 is the lighter option — 135 g lighter than the Decathlon Forclaz MT900 UL 50+10L (10% less weight). If grams matter to you, that is the one to beat.
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Spec Black Diamond Speed 40 Decathlon Forclaz MT900 UL 50+10L
Weight 1,180 g · 1.180 kg · 2.60 lb 1,315 g · 1.315 kg · 2.90 lb
Brand Black Diamond Decathlon
Category Backpack Backpack
Black Diamond Speed 40
1,180 g

Lightweight 40L alpine pack with removable framesheet.

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Decathlon Forclaz MT900 UL 50+10L
1,315 g

Affordable ultralight backpacking pack with 50L capacity plus 10L extension collar. Highly functional load lifters and large front pockets. Budget-friendly entr...

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Black Diamond Speed 40 vs Decathlon Forclaz MT900 UL 50+10L: which should you buy?

If saving weight is your priority, the Black Diamond Speed 40 wins — at 1,180 g it is 135 g (10%) lighter than the Decathlon Forclaz MT900 UL 50+10L (1,315 g). That said, the heavier option may justify the extra grams with more capacity, durability or comfort, so weigh the trade-off against how you'll use it.

See where both rank against everything else in this category on the lightest backpack page, or browse the full gear weight database.

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