Material: Why Merino Wool is the high-performance HYROX choice

Meridri™: engineered for HYROX

Many people think of wool and immediately think of warmth and comfort, and as Merino wool as the luxury version of that. In fact, in the trail running and ultra-marathon community, Merino wool has long been prized as the highest performing sock material. Not for it's warmth, but for Merino's unique ability to manage moisture, which in term reduces blisters and provides reliable comfort for miles of running. We took what the ultra marathon industry learnt, and we applied it to a sock designed for HYROX from the sole up.

Meridri™ is our proprietary blend of compact-spun merino wool and performance polyamide, zone-mapped to the specific demands of HYROX competition. Here is what it does, and why.

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The foot zone: Meridri™ blend

The section of the sock covered by your shoe, in direct contact with your skin across thousands of ground strikes, is where moisture management and comfort matter most.

Why merino

Merino fibre has a dual structure no synthetic replicates. The outer layer repels liquid water. The inner core absorbs moisture as vapour, before it becomes liquid on your skin. Each fibre holds up to 30% of its weight in moisture while your foot remains dry to the touch.

Each fibre holds up to 30% of its weight in moisture

When sweat production increases, which in a 90-minute HYROX effort it will, capillary action between fibres draws liquid moisture away from the skin and distributes it across the fabric surface for evaporation. No cold, clammy sensation. No saturation point.

Merino also thermoregulates. It creates a microclimate against your skin, releasing excess heat during intense effort and retaining warmth when you cool. In an exhibition hall with hard concrete underfoot and rising ambient temperature, this is not a comfort feature. It is a performance one.

Why compact spinning

Standard ring-spun merino leaves loose fibre ends at the yarn surface, these are the fibres that pill and wear under repeated friction. Compact spinning draws all fibres tightly together before twisting, eliminating surface ends before they can become a problem. The result is a denser, more abrasion-resistant yarn that maintains its structure through training cycles and race days without sacrificing the softness or moisture performance of the merino.

Why polyamide in the blend

At peak exertion, merino's absorption system can reach capacity. Polyamide's smooth fibre surface provides fast surface transport for heavier sweat load, moving moisture outward when the merino system is working hardest. The two materials handle different stages of the same problem.

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The compression zones: polyamide elastane blend

The compression zones of the Bold Block Merino, are a blend of polyamide and elastane.

They are designed to hold precise compression in the areas where you need it, without squeezing the toes or toe box, supporting good natural foot posture, balance and comfort.

without squeezing the toes or toe box, supporting good natural foot posture, balance and comfort.

The compression zones are engineered for structural precision. The moisture management system operates in the foot zone, where it is needed.

Each material is doing the job it is best at, in the part of the sock where that job matters most.

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The Meridri™ blend

Fibre sourced from Australia and New Zealand. Six months of prototype development and competition testing before production. Meridri™ is knitted into the sole of every pair.

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The Bold Block Merino. Built for HYROX. Nothing else.