When winter sets in, the cold demands that athletes build their outfit from the base up: the first layer. In direct contact with the skin, the thermal base layer is the cornerstone of your thermal regulation. Its role is twofold: insulating you from the cold while wicking away sweat to prevent the "fridge" effect the moment you stop.
Our selection: Which base layer for your activity?
There's no one-size-fits-all base layer — there's a model suited to every intensity and every temperature. Here are our recommendations based on Cimalp technologies.
The most natural: WOOL TOP 200 in merino wool
Who is it for? Expedition enthusiasts, winter hikers or skiers.
This model uses the exceptional properties of merino wool. It's the ultimate fibre for those seeking consistent warmth and natural odour management.
- The key strength: Merino regulates temperature dynamically: it keeps you warm in extreme cold and breathes when effort intensifies. It's the ideal choice for activities that alternate between high-output phases and static phases.
- Use: Mountaineering, winter hiking, long-haul travel.
The softest: The Bamboo + Silk combination of the STRATEGIC TOP and PANT
Who is it for? Sensitive skin and wellness activities.
This duo of natural fibres offers an incomparably soft feel. Bamboo, naturally antibacterial, is paired with silk, one of the world's finest thermal insulators given its fineness.
- The key strength: Absolute "cocooning" comfort and a seamless construction that prevents any irritation. This base layer wears like a second skin, whether on a light hiking trip or day-to-day.
- Use: Hiking, Nordic walking, skiing.
The most versatile: WARM TOP (CimaWarm® technology)
Who is it for? Those looking for balanced warmth for cold-weather activities at an unbeatable price-to-performance ratio. The WARM TOP uses the technical CimaWarm® fibre with hollow fibres and a brushed inner to create a lightweight, high-performance thermal barrier.
- The key strength: Excellent insulation combined with optimal moisture transfer. Its soft inner delivers an immediate feeling of warmth without ever stifling the body during exercise.
- Use: Cross-country skiing, snowshoeing, Nordic walking, hiking.
The most technical: The SEAMLESS TOP
Who is it for? High-intensity athletes.
This base layer is defined by its seamless construction, eliminating any risk of chafing or heat build-up during exercise. Its lightweight fabric disappears the moment you put it on.
- The key strength: Ultra-fast moisture evacuation. Technical synthetic fibres dry in record time, keeping the garment dry.
- Use: Trail running, skiing, winter hiking.
The warmest: X-WARM ZIP
Who is it for? Athletes who train in extreme cold and static cold conditions.
When temperatures drop sharply, the X-WARM ZIP is your best defence. Designed with hollow fibres that trap maximum warm air, this model puts thermal insulation first.
- The key strength: Massive heat output. This is the base layer you choose when staying still (watching the Northern Lights, bivvy) or for the coldest alpine skiing days of the season.
- Use: Extreme cold, skiing, mountaineering.
The natural featherweight: WOOL TOP 150
Who is it for? Mid-season hikers or for multi-layer use in demanding activities. Its fineness (150g/m²) makes it the lightweight, comfortable base layer par excellence. It offers all the benefits of merino with zero itching.
- The key strength: Zero odour and subtle thermal regulation that prevents overheating on sunny days or spring ascents.
- Use: Skiing in mild conditions, travel, autumn/spring hiking.
The essential accessory: UNDER Boxer
Who is it for? Those who want to optimise the 3-layer system. Moisture management must start from the very first centimetre of skin. Wearing a technical top over a cotton base layer is a classic mistake that creates a cold, damp zone.
- The key strength: Sweat evacuation where it matters most, with flat seams to prevent irritation on long walks.
- Use: All sports activities and long-distance hiking.
The essential properties of a good base layer
To be effective, a technical base layer must do more than just "keep you warm". It must disappear thanks to precise characteristics:
- The tailored fit: A close-to-body cut is vital to minimise pockets of cold air and prevent chafing.
- Seamless construction: It eliminates irritation zones during repetitive movements.
- Moisture evacuation: This is the heart of the technology. The fabric must wick sweat away and push it outwards to keep your skin dry.
- Odour management: Thanks to natural fibres or antibacterial treatments, you stay fresh even after hours of effort.
The importance of a fitted cut
For these technologies to work, the fabric must be in direct contact with the skin. A base layer that's too loose will create internal air currents that cancel out the thermal effect. Don't be put off by the fitted look: the elasticity of our fibres ensures total freedom of movement, whether you're planting a pole or mid-stride.
