Winter Cycling Base Layers

Buying Guide

When winter riding becomes part of your routine, a high‑quality base layer is no longer optional – it’s essential. The right cycling base layer for winter can be the difference between an enjoyable, consistent training ride and cutting things short due to cold, sweat build‑up or discomfort. Including winter cycling base layers as a key part of your cycling wardrobe ensures you have the versatility and performance needed for a range of winter conditions.

Why Winter Cycling Base Layers Matter

A base layer’s job is simple in theory, but critical in practice: manage moisture and regulate temperature. In winter, this becomes more challenging because conditions are often cold, damp, windy – and variable.

Unlike summer base layers when airflow helps cool you, winter riding demands insulation without overheating. A good winter base layer:

Wicks sweat away from the skin to keep you dry and comfortable
Traps air to help keep your core warm and maintain stable body temperature
Works with your other layers for optimal insulation and moisture management, not against them
Reduces the risk of chills on descents or café stops

This is why cyclists searching for the best cycling base layers should always start with intended conditions and riding intensity, rather than just thickness alone. At Sigma Sports, we stock thermal base layers, windproof base layers and long sleeve base layers ideal for the colder months.

Recommended Winter Cycling Base Layers

While this guide focuses on how to choose, these standout options illustrate what makes a great winter base layer. Each of these reflects different priorities, from maximum warmth to breathability and versatility, ensuring you stay comfortable and protected from the winter chill.

Best Long Sleeve Base Layer

Castelli Flanders 2 High Neck Warmer Base Layer

The Castelli Flanders 2 is widely considered the ultimate deep-winter base layer because it combines maximum insulation with a highly versatile design.

Extreme Warmth: Utilising SottoZero fleece, it is Castelli’s warmest synthetic layer, specifically engineered to trap heat and wick moisture in temperatures as low as -4°C.
Integrated Protection: The built-in high neck is a "3-in-1" solution, functioning as a neck gaiter, face mask, or helmet liner to seal out icy drafts.
High-Intensity Comfort: It balances warmth with performance through mesh armpit inserts for ventilation and flat Merrow stitching to prevent chafing during long efforts.
Low Bulk: Designed to fit seamlessly under a winter jacket, it provides substantial thermal protection without the restrictive "bunched up" feeling of multiple thick layers.

Best Short Sleeve Base Layer

Castelli Core Seamless Short Sleeve Base Layer

The Castelli Core Seamless Short Sleeve is the ideal choice for transitional weather, offering a "second-skin" fit that excels at moisture management and comfort.

Advanced Moisture Control: The blend of polypropylene and polyester yarns is exceptionally soft and stretchy, designed to pull sweat away from the skin instantly to keep you dry during high-output rides.
Seamless Comfort: The seamless construction eliminates pressure points and friction, while the wide neck opening ensures it remains invisible and comfortable even under low-collared race jerseys.
Targeted Breathability: It features lighter-weight fabric on the sides and back, providing extra ventilation where you need it most to prevent overheating.
Versatile Layering: Optimised for a broad temperature range (8°C to 20°C), it adds just enough thermal protection for chilly mornings without feeling bulky as the day warms up.

Best windproof base layer

GOREWEAR Thermo WINDSTOPPER Long Sleeve Base Layer

The Gore Wear Thermo WINDSTOPPER Long Sleeve is a specialised piece of kit designed to be the ultimate shield against wind chill, making it ideal for high-speed descents or gusty, cold conditions.

Strategic Wind Protection: It features Gore® WINDSTOPPER® inserts on the front, shoulders, and kidney areas, the parts of your body most exposed to the wind, effectively blocking cold air from penetrating your core.
Thermal Flexibility: The thermo-stretch fabric provides breathable insulation that moves with you, ensuring you stay warm without sacrificing the mobility needed for a performance cycling position.
Cycling-Specific Fit: An extra-long back ensures full coverage and prevents the layer from riding up when you are tucked in the drops, protecting your lower back from exposure.
Low-Friction Design: By using minimised, flat-lock seams, Gore has reduced the bulk and potential for chafing, making it comfortable for long-distance rides under a jacket or jersey.

Best Thermal Base Layer

Universal Colours Thermal Long Sleeve Base Layer

The Universal Colours Thermal Long Sleeve is a standout choice for eco-conscious cyclists who need high-performance insulation for rides ranging from mild single digits to sub-zero.

Polartec® Power Grid Technology: The use of Polartec® Power Grid fabric creates a "grid" of air channels that trap heat for instant warmth while remaining incredibly lightweight and breathable.
Superior Moisture Management: This specific knit structure is designed to pull moisture away from the skin and disperse it rapidly, ensuring you stay dry and comfortable even during high-effort climbs.
Eco-Friendly Construction: It is a leading choice for the environmentally-conscious, made from 49% recycled post-consumer waste and produced in socially audited facilities.
Highly Adaptable Layering: Optimized for 0°C to 10°C, its low-bulk design makes it exceptionally versatile for layering under a thermal jersey or a windproof gilet as the temperature fluctuates.

Best Mens & Womens Base Layer

Assos Spring Fall Long Sleeve Base Layer P1

The Assos Spring Fall Long Sleeve P1 is widely regarded as a benchmark for 3-season performance, offering a sophisticated "second-skin" fit that excels at balancing temperature during fluctuating effort levels. We've also selected the womens fit of this ASSOS base layer as the best base layer for female cyclists.

Dynamic Thermal Regulation: It features a body-mapped weave, a tight knit on the front to shield the core from cool air, and a more open weave on the back and underarms to vent excess heat during hard efforts.
Next-Level Comfort: This generation is 15% lighter than its predecessor and uses a single-piece seamless construction, eliminating friction and ensuring a perfect fit under aerodynamic jerseys.
Odour Management: The fabric is infused with carbon, providing permanent antimicrobial properties that prevent odors from building up, no matter how much you sweat.
Versatile Layering: Specifically engineered for the "shoulder seasons," it is the ideal companion for spring/fall jerseys, maintaining comfort in both cool morning air and warmer afternoon sun.

Best Merino Cycling Base Layer

Rapha Women's Short Sleeve Merino Base Layer

The Rapha Women's Merino Base Layer is the gold standard for riders seeking a natural, high-performance fabric that provides versatile comfort across all four seasons. There is also a version of this item for male cyclists.

Premium Merino Blend: The proprietary 160gsm merino blend offers a superior balance of insulation and breathability, making it light enough for summer climbs yet warm enough for crisp autumn mornings.
Natural Odour Resistance: Thanks to the inherent properties of merino wool, this layer is naturally anti-bacterial and odor-resistant, allowing it to stay fresh during multi-day trips or long endurance rides.
Refined "Itch-Free" Fit: The updated design includes extra elastane for a closer, more aerodynamic fit, while flatlock seams ensure the fabric remains soft and irritation-free against the skin.
Exceptional Durability: Unlike standard wool, this technical blend is engineered to be lighter and more durable, reducing moisture retention and ensuring the garment maintains its shape through repeated use and washing.

How to Layer a Winter Cycling Base Layer

A base layer works best as part of a system:

Base layer – moisture management and insulation
Mid‑layer (optional) – thermal jersey or fleece for very cold days
Outer layer – wind and wet weather protection

Adding other layers on top of your base layer can provide extra warmth and help you stay warm during winter rides, especially in colder or more challenging conditions. For most UK winter conditions, a well‑chosen base layer paired with a thermal jersey or softshell jacket is sufficient.

Fabric Choice: Synthetic vs Merino Wool

The material of your base layer plays a huge role in comfort and performance.

Synthetic base layers (polyester or polyamide blends):

Excellent moisture‑wicking
Dry quickly
Often lighter and more elastic
Ideal for high‑intensity winter training
Impressive wicking abilities to draw sweat away from the skin

Merino wool base layers:

Naturally thermoregulating
Excellent odour resistance
Warm even when damp
Perfect for long rides and variable conditions
Made from natural materials with outstanding insulating properties
Provides effective odour control for lasting freshness

Many of the best winter cycling base layers now blend merino with synthetics, combining warmth, stretch and durability. Some base layers also use mesh fabric for enhanced breathability and a super soft feel.

Fit, Construction & Selecting the Right Weight

A "second-skin" fit is essential to eliminate cold air pockets and facilitate efficient moisture wicking. To avoid chafing and ensure comfort under bib shorts, look for:

Anatomical cycling cuts with stretch fabrics.
Seamless or flat-lock construction to minimise friction.

Since no single layer covers every condition, choose a weight based on intensity and temperature:

Lightweight: Ideal for mild autumn days or high-intensity efforts.
Midweight: The most versatile choice for standard winter conditions.
Heavyweight/Thermal: Best for "deep winter" or slower, colder rides.

Sleeve Length: Long vs Short Sleeve

It’s a common misconception that winter always means long sleeves.

Long sleeved winter base layers with long arms provide extra coverage and warmth, helping to retain heat and prevent gaps at the wrists for enhanced comfort in cold weather.
Short sleeve base layers can work well under thermal jerseys or softshells, allowing better temperature control during harder efforts.
Different length sleeve options are available, including sleeveless base layers for flexibility in hot or changeable climates, or for those who prefer to combine them with other layers.
Arm warmers can be paired with sleeveless or short sleeve base layers for adaptable layering, offering additional warmth and flexibility as conditions change.
All base layers can be worn under a regular jersey for added insulation and comfort during winter rides.

Choosing between them depends on layering strategy, not just temperature.

Wind Protection Base Layers

For exposed winter riding, wind is often the real enemy. Some advanced winter base layers now integrate windproof panels on the chest or front torso. For added insulation, you can use an extra layer beneath windproof base layers, especially on the coldest days.

Many windproof base layers also feature a wide collar to enhance comfort and wind protection, particularly when layering beneath jackets or skinsuits. Additional details like thumb holes or thumb loops help keep sleeves in place, prevent cold gaps, and improve overall fit and warmth during winter rides.

These are particularly effective when:

Riding in strong headwinds
Wearing more breathable outer layers
Training at lower intensities

A windproof base layer can reduce the need for bulkier jackets while maintaining warmth.

Conclusion

To maximise your investment and comfort, avoid common pitfalls like choosing non-cycling-specific thermals, ignoring wind chill, or wearing a layer that is too thick, which leads to overheating and chill-inducing sweat. A high-quality, task-specific base layer is one of the most cost-effective upgrades you can make, transforming cold-weather training into an enjoyable experience. By selecting a versatile range of layers tailored to your riding intensity, you can stay dry, warm, and prepared to ride through the heart of winter.