Whatever the weather, the right base layer can help keep you comfortable on the bike by providing insulation, wicking sweat away from your skin or both.
Lightweight synthetics are good for summer use, while Merino wool has fans all year round because it can be worn repeatedly without getting smelly.
For winter use look for features like a high neck, thumb loops and a zip for cooling
Minimalism is the watchword in summer, but short sleeves — rather than a sleeveless design — can still help provide a little crash protection
You can’t build a house without first building solid foundations, and it’s the same when dressing for cycling; it all starts with a decent base layer.
Also known as an undershirt or vest for the jargon-averse, getting the right base layer against your skin can make a big difference to cycling comfort all year round. In winter you wear more layers, and arguably the most important layer is a base layer. How many layers you wear over the top is down to riding conditions, temperature, weather, duration, intensity and personal preference. Start with a good base layer and you’re off to a good start to cycling happily through the winter.
A base layer isn't quite as important in the summer, but can still make a useful contribution to your on-bike comfort. A lightweight base layer will help move sweat away from your skin, a job some jerseys don't do quite as well as you might hope. And there's another reason why you'll often see pros wering base layers even in the height of summer: if you crash, your jersey will slide over your base layer, reducing damage from abrasion.
Choosing the right base layer
The job of a base layer is quite simply to keep you dry when you’re sweating, by pulling moisture away from your skin. A base layer also provides a layer of insulation, and you can tailor how much insulation by the base layer you choose. As the base layer sits next to the skin, comfort is vital so it’s worth investing in a high quality base layer. You don’t want any irritation when you're cycling.
Base layers came in many varieties: different sleeve lengths, different fabrics and weights, high collars and low collars; no two base layers are the same. A base layer doesn’t have an easy job, and the trick is to find one that suits your demands and style of riding.
Lightweight base layers are ideal for year-round cycling and suit hard charging cyclists who produce a lot of sweat. They are good at keeping you comfortable on fast-paced rides or warmer days, or when climbing lots of hills.
Heavier weight base layers are good for really cold days and providing essential warmth, or when you’re riding at a lower intensity - maybe touring or cycling to work.
Long or short sleeve, or sleeveless?
You can choose base layers with short or long sleeves, or sleeveless. Sleeveless and short sleeves are best suited for warmer days and the summer, but depending on the layers you’re putting over the top, and how cold it actually is, a short sleeve base layer can still be useful in the winter. Sometimes it’s simply not cold enough for a long sleeve base layer, and you can always add arm warmers if going with short sleeves.
Long sleeves are the business for the coldest days though, and paired with a soft shell jacket offers perhaps the most versatile and suitable outfit for typical UK winter weather. A long sleeve thermal base layer and good soft shell jacket is a really good setup, for example.
Base layers come in a variety of materials, falling into two camps; man-made and natural materials.
Merino wool is the most common natural fabric base layer. Merino is great because it copes with a wide range of temperatures and doesn't pong when you get sweaty, and it’s very soft next to the skin. It comes in different weights to suit different temperatures, from lightweight to thermal insulation.
Not all merino base layers are the same, there are different weights of merino, and some use 100% merino wool for the construction while some combine merino with another material like polyamide or polyester to provide extra stretch for a better shape and more durability, so you get the best of both worlds, with the faster drying time of the man-made fabric. Such material blends are also easier to care for than 100% merino wool base layers.
If you are cycling every day, or you’re riding twice a day because you’re commuting to the office, then a merino base layer has the advantage that you can wear it for several rides before it needs a wash. Just hang it out to dry and it'll be good to go again.
Man-made synthetic base layers like polypropylene and polyester are generally better at wicking sweat and are usually much lighter, and many people prefer how they feel next to the skin. Such materials can get smelly when you sweat though, so you certainly can't wear them for multiple rides, but recent material developments have seen this become less of an issue than it used to be.
Man-made materials are typically better at actually wicking sweat away from the skin. Whereas merino holds onto the moisture (but retains heat so doesn’t get cold), man-made materials provide excellent wicking properties and don’t hold onto much water. They dry quickly, so are ideal for high intensity cycling. Man-made material base layers are also less bulky and typically provide a closer fit on the body than merino base layers.
Aside from material choice, base layers are available in a wide range of thicknesses, from lightweight summer tops to chunky Arctic-ready base layers. You need to take into account the average temperature that you aim to ride in, the duration and intensity of your cycling, and what layers you plan to wear over the top, to help you decide what base layer is right for you.
Some people also run hotter, and so can get away with a lighter weight base layer, and some people need the extra insulation of a thicker grade base layer. So try and choose the base layer that best fits your requirements. What works for one person won’t necessarily work for you, everyone is different, and experience is the only way to find what works for you.
Some base layers are offered with a wind stopping material used in the chest panels. Why? With wind protection next to the skin, it frees you up from having to wear a windproof outer layer and gives you a little more versatility. For example, you could combine a windproof base layer with a long sleeve jersey that doesn’t have any wind resistance, with the base layer keeping the wind out, providing a good option for high intensity riding. However while they might sound perfect they don’t handle the buildup of heat as well as regular base layers so it’s possible to overheat in them
The weather in the UK can vary hugely, even from one day to the next, so having a couple of different base layers so you can dress appropriately is a good way forward.
Fit and shape
For a base layer to do its job most effectively, the material should sit flush with the skin. If you’re riding at a lower intensity or commuting, then a looser baggy fitting base layer may be fine, but for higher tempo cycling when you expect to produce a large amount of sweat, look for a close fitting base layer.
The more stretch a fabric is generally the better the fit. Also look for smartly placed seams to avoid discomfort, the base layer will dictate the comfort of your whole outfit so check the insides carefully.
Comfort is critical and it’s not just the material being soft next to the skin that is important, t’s also worth looking for a base layer flat seams and no labels or tags, anything that can cause irritation or discomfort.
Most base layers have low neck lines but some heavier duty base layers can have taller necks to provide more insulation on cold days. Some base layers have a zipped neck which can be useful to ventilation on longer climbs or if you find yourself overdressed.
Also check the length of the arms on a long sleeve base layer, you don’t want them coming up short on your wrist, but you also don’t want any material bunching up in the sleeves of your jersey or jacket.
Another thing to consider is length. Some base layers have more length so you can get a good overlap with your bib tights, providing a bit of extra insulation around your lower midriff. Some base layers are a bit lower at the back also to make sure there’s no chance of exposed skin when crouched over the handlebars.
Caring for your base layer
Most base layers these days can be chucked in the washing machine on a regular wash with your other cycling clothes. However, it is important to check the washing and care instructions with any base layer. Merino can shrink on a high temperature wash, but many merino base layers are fine at 40°C. With merino they'll usually tell you not to dry clean or tumble dry, and to dry away from direct heat, so no draping over your radiator.
There’s a trend towards lower temperature washes with modern washing machines but such washes don’t always deal so well with the buildup of bacteria on base layers, which causes the pongy smell.
15 of the best base layers
As there's so much choice out there, we've picked 15 of the best base layers from the road.cc review archive to provide a good starting point, and demonstrate the variety of choice available. Most of these base layers are available for men and women.
Not enough choice for you? Browse the full archive of base layer reviews
dhb's Blok Mesh Sleeveless Baselayer is a no-frills lightweight top, but you get a lot for your money according to our reviewer Ash: "it does as good a job as more expensive ones, and just makes me ask: why would you spend more?" This is actually the latest version and has gone up a fiver since Ash reviewed it, but the materials used and performance have remained despite a colour change. It's got a very light mesh fabric and features Polygiene anti-odour treatment, with flatlock stitching throughout for extra comfort.
'Infused with crushed volcanic rock.' That's the blurb for the fabric used on the front panels of the Pearl Izumi Transfer Sleeveless Baselayer. With claimed properties of excellent moisture absorption, great wicking and odour elimination, it covers everything an underlayer needs to provide. And do you know what? It delivers.
The Transfer baselayer feels great in your hands even before you put it on, and you just know it is going to sit softly against the skin with no part itching or scratching as you ride.
Like many other tops of its kind, the Lusso Race Base Mesh Base Layer works really well in warm conditions, wicking away sweat and keeping you cool, but it's the overall design and fit that makes the Lusso stand out.
The cut is more like a race jersey than an undergarment, and you certainly feel ready for your ride when you put it on.
As with all of Lusso's kit, the Race Base is made here in the UK and it's good to see that homegrown goods can still compete on price: at £24.99 it's a good tenner cheaper than the recently tested Castelli Pro Issue and even less than the Hackney GT Bang.
Lusso hasn't achieved that price by scrimping on quality either. The overall construction is very neat and tidy – the whole thing just screams a top notch jersey, and it feels impressively durable too.
The Ekoi Morpho Senza Unisize is an excellent baselayer, shifting sweat really well to keep you dry and comfortable.
This top is made from Dryarn – 80% polypropylene and 20% polyester. Perhaps I've been doing this job for too long, but I know from experience that polypropylene makes excellent baselayers because it's very lightweight and doesn't absorb sweat. That's exactly the performance you get here, the fabric moving moisture away from your body quickly and effectively without getting waterlogged itself.
The Lusso Dryline Baselayer promises to be lighter and more insulating than merino. Performance is indeed very good and it fits like a glove.
When something only weighs 78g, arguing the toss about lightness is only relevant to the most weenie of weight watchers. That said, the Dryline Baselayer is indeed very light. It's made from Dryarn, an Italian fabric that's claimed to be lighter, more breathable and more insulating than pretty much anything else. I'm a huge fan of merino baselayers – mesh and normal – for warmth, cooling and moisture control, so approached the claims of the Lusso base with a sceptical eye. The bottom line is that the Dryarn fabric is indeed very good at keeping you warm, cool or dry, or a combination of the three.
Tester George Hill says: "The Craft Active Extreme 2.0 CN LS is an excellent baselayer that manages heat better than almost any I have used. Having worn this in freezing and mid-range conditions, I can testify that not only does it keep you warm, it also has great wicking and breathability.
"Craft describes it as a baselayer for 'medium-cold to cold conditions'. This is fairly ambiguous and open to a wide range of interpretations, especially as Craft is a Swedish company, so its medium-cold is probably our hypothermia-inducing. I used it in temperatures varying from -3 to 10 for the duration of the review."
The Castelli Pro Issue SS Base Layer is a superlight, super-comfortable baselayer that performs brilliantly and has topped my list of go-to layering, writes tester Sean Lacey.
Made from 100% polyester 3D mesh fabric, first impressions are that it doesn't seem to weigh anything, and if you are a bit prudish it is almost see-though. Lingerie it is not, though, and its credentials include a wider neck for a better fit under a tight collared or aero jersey, reduced seaming on the shoulders for comfort, and a flat hem so it doesn't create a point of irritation on the waist.
Simple and effective, the Altura Dry Mesh Baselayer should be an essential part of every cycling wardrobe. The benefits of wearing a baselayer are well known among amateur and pro cyclists alike, which is why you'll see racing cyclists on Alpine climbs, jerseys open with a mesh layer on show. The thin open mesh approach to baselayer design allows for increased evaporative cooling when exposed or beneath a layer or two of clothing, cutting down on the time that perspiration sits next to the skin, creating more comfortable riding conditions.
Hackney GT's Bang Unisex Performance Base Layer is a functional and versatile piece of kit that has fast become one of our favourite 'essentials'. Its performance in both hot and cold weather is superb, making it a great all-year-round choice and even better value.
The vest is super-lightweight and very soft to the touch. It's made from a fabric called Aviatar, a perforated polyester designed to work in all seasons and weathers, with the side panels made of Lycra to offer a little more give.
With the WindBloc S/S Base Layer Lusso has taken the Dryline base layer and added a windproof layer on the front of the torso. It works a treat, offering excellent moisture wicking and a useful amount of protection for fast descents.
A good baselayer wants to sit closely against the skin to maximise its ability to 'wick' – to take sweat from your skin and move it away for evaporation. Various fabrics can do this effectively, including merino wool and some synthetics, and the construction of the fabric can play as significant a role as the raw material itself.
Here Lusso uses Dryarn, made from polypropylene, which it claims is "more breathable than polyester, more insulating than wool and lighter than any other fibre" – bold claims. In use I found it did indeed perform very impressively – the Dryarn is used across the whole baselayer except for the black windproof panel on the front. Even working hard on big Pyrenean climbs I found not a hint of moisture build-up in the usual sweat-trap areas.
The skin tight Sportful 2nd Skin Long Sleeve T High Collar is comfortable, warm and copes well with sweat. It's a good investment for the winter. It's made from 60% polyproplyene, 27% polyester and 13% nylon. Sportful has used body mapping to add in mesh fabric in key areas, to help with temperature regulation.
The Craft Zero Extreme Windstopper base layer adds superior wind protection for beating the chill. Craft add a Gore Windstopper membrane to the chest panel of this base layer, which adds impressive protection against the wind. With wind protection next to the skin, it frees you up from having to wear a windproof outer layer and gives you a little more versatility.
The Rapha Women's Long Sleeve Base Layer is a soft, breathable base layer made from merino wool that will prove useful time and time again, both on and off the bike. This lightweight top is made from 100% merino, which might head off some of the haters at the starting line.
The X-Bionic Energy Accumulator V2.1 is a fantastic baselayer. And given the price, that's exactly what you should expect. You won't be disappointed, though, this one really delivers. It's among the very best winter baselayers we've tried.
Rapha has a wide range of base layers from lightweight summer numbers to deep-winter Merino mix undershirts with windproof fronting to fight the chill. Their lightweight Merino base layer is a longstanding favourite, while the Winter Base Layer is a toasty merino offering with a unique design that'll help to keep you cosy.
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David has worked on the road.cc tech team since July 2012. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds.