The humble base layer is the foundation of any comfortable outfit. More critical than ever once the temperature drops, in winter a cycling base layer should manage the indispensable task of keeping your core warm and dry.
Letting you ride on in comfort, unlike your everyday cotton t-shirt which will rapidly absorb sweat, cycling clothing tends to employ either synthetic fibres or natural Merino wool.
The result is that even when damp your base layer will retain most of its insulating properties. Also allowing it to continue wicking away moisture, this means that pulling one on will reduce the risk of you ever feeling clammy or catching a chill.
Here are a look at eight of the best winter base layers for cycling
Best winter base layers for cycling
- Castelli Flanders: RRP £90
- Isadore Merino: RRP £80
- Spatz Basez 2: RRP £74.99
- Craft Active Extreme 2.0 CN: RRP £44.99
- Rapha Thermal: RRP £90
- Megmeister Drynamo: RRP £55
- Endura BaaBaa Merino Blend: RRP £59.99
- Universal Colours Thermal: RRP £65
Related questions you can explore with Ask Cyclist, our new AI search engine.
Best winter cycling base layers 2025
Castelli Flanders long sleeve base layer
£72 (RRP £90) | View offer
A garment named after professional cycling’s most gnarly playground, the Castelli Flanders base layer has been designed in mind of the most hostile of February days in the Flemish Ardennes.
It does that by relying on a high-loft fleeced inner material that manages to provide warmth and comfort to the skin while also quickly wicking away any sweat you produce. To prevent overheating, the armpits are mesh and the flat hem bottom means this base layer tucks perfectly into a set of shorts or bibtights.
We are also fans of the mock turtle neck, sitting a little higher it gives you a few more centimetres of protection for your chest and neck.
Being Castelli, we would also recommend sizing up as the fit can be quite racy and ultimately you want comfort from your winter base layer.
Isadore Merino base layer
£80 | View offer
Another brand to utilise merino wool, Isadore offers a premium product that it promises can be raced in. Expected considering the brand is the brainchild of former pro brothers, Martin and Peter Velits.
In a slimmer cut, Isadore's offering fits slightly different to most other options, being a little tighter but this doesn't subtract from comfort which is provided by the soft material.
The little touches have also been remembered including thumb holes on the cuffs, a lower cut and unrestricted neck and the choice of five colours. Available from XS to XXL.
- Read our full Isadore Merino base layer review
- Buy now from Isadore (£80)
Spatzwear Basez2 base layer
£74.99 | View offer
It seems to be that if you know about Spatzwear, you know. The small Yorkshire-based brand that started on a quest to make the perfect overshoe after countless sodden miles ridden through the Dales.
After conquering the overshoe, Spatz has expanded into the world of base layers with the Basez2 which claims it will be ‘the most technically advanced base layer you’ll ever own’.
An extended rear section protects from draft seeping through the back of your jacket, thumb loops help keep the sleeves pulled down and a high neck negates the need for a buff or snood. It’s even good enough for the current men’s road race Olympic Champion too.
- Buy now from Sigma Sports (£74)
Craft Active Extreme 2.0 CN base layer
£20 (RRP £44.99) | View offer
Hailing from Sweden, Craft knows a thing or two about keeping warm, and that’s apparent in its Active Extreme base layer.
The polyester/elastane mix used in this garment gives this a thinner feel than the others on test. Something that’s evident in the saddle, too.
This is a base layer better suited to milder autumn rides (or maybe Swedish summer ones) than ones when a southwesterly is blasting you with freezing air fresh from the Atlantic.
On warmer rides, you’d have no worries about sweat, however, as the fabric used scores highly for its wicking abilities, while its design also helps to keep body temperatures down.
Loose rather than close-fitting, its ribbed pattern keeps the material thin and stretchy while separate mesh panels around the armpits lend the garment even greater breathability. Available in black, French blue and white, in sizes S-XXL.
- Buy now from Decathlon (£20)
Rapha Thermal base layer
£90 | View offer
Not much comes cheap with Rapha but that's for a reason. Extra care in manufacturing has helped it produce products that stand the test of time, just like this thermal base layer, made in two weights of Polartec fabric and an excellent first layer for any ride in slightly colder conditions.
The fit is close making it perfectly acceptable for a fast chain gang or even racing while low-profile seams reduce on irritation, often an issue with base layers. The high neck is good too and does away with the need for a snood. Available in black, navy and plum in XS to XXL.
- Buy now from Rapha (£63)
Megmeister Drynamo
£49.99 (RRP £55) | View offer
Nothing to do with Bradford-born magicians, everything to do with staying warm on the bike through winter.
The best thing about this base layer from Megmeister is its ability to manage your body temperature, keeping you warm enough to stave off the shivers while allowing enough heat to escape when you begin to wrench it up a climb. It also does a good job of managing moisture and doesn’t hold odours, which is always a bonus.
One point of note is that it comes up fairly big so do not be scared about buying true to size or even a size down.
- Buy now from ForRunnersByRunners (£49.99)
Endura BaaBaa Blend
£59.99 | View offer
Endura's base layer is a mix of 20 percent Merino wool with 80 percent Lyocell, giving a good mix of warmth without weight along with a dose of softness, sweat dispersion and odour resistance. Plus, it's machine washable unlike some woollier mixes.
Available in five sizes and five colours, it's a versatile bottom layer that won't break the bank.
- Buy now from Merlin Cycles (£48)
Universal Colours Thermal
£65 | View offer
UK-based Universal Colours uses Polartec Power Grid fabric for its cold weather base layer. The gridded structure is made from recycled polyester and helps trap warm air next to the skin, while wicking very effectively.
There's a high collar and close cuffs to help keep air in and enough stretch than three sizes cover riders from XS to XXL. Black or navy options offer a bit of variety for your cold weather first layer.
- Buy now from Sigma Sports (£48)
