Baselayers are there to keep you comfortable while cycling. They do this in two ways: by trapping a layer of air next to your body to keep you warm, and by transporting sweat away from your skin to keep you dry.
If you want to get technical about it, a baselayer forms the bottom of a multi-layer clothing system designed to manage the climate differential between the inside and outside of your garments.
As such, you’re likely to wear them on all but the very hottest days. Here’s everything you need to know about baselayers and how to choose the right one for you.
How do baselayers work?
Some baselayers wick moisture away from the skin through capillary action (the fabric’s inner face has lots of tiny voids to make it porous), while others do it using hydrophilic coatings that work to actively draw moisture through the garment.
Either way, the idea is to move moisture away from the skin, in order to help regulate your body temperature.
What are baselayers made from?
Polyester vs Merino wool
Broadly speaking, baselayers are made from synthetic fibre (such as polyester blends) or natural fibres (in most case, Merino wool).
Synthetic fibres can be manufactured with hollow channels to aid the wicking process and can be incredibly efficient as moving sweat and drying quickly.
The downside is that they get smelly fast, so most now come with some form of antibacterial treatment.
Merino wool is naturally antibacterial, so it can be worn for extended periods without needing washing, and feels often feels luxuriously soft against the skin.
However, it doesn’t wick as well, takes longer to dry and can feel damp next to your skin, although it does still maintain its ability to insulate.
Many higher-end baselayers are now made of a mixture of wool and synthetic fibres, for the optimum combination of comfort and performance. This means they provide a lot of warmth at a lighter weight and drying faster than pure wool.
What to look for in a baselayer
When it comes to choosing a baselayer there are other things to consider besides the material it’s made from. It’s important to think about the fit, thickness of material used, warmth you’ll need from it and odour management.
Warmth (but not too much)
Baselayers provide warmth by trapping air next to the skin. This effect is due to the weave design, the fabric fibres used, or a mixture of both. The colder the conditions, the thicker the baselayer you use.
How warm you want your baselayer to be depends on how warm you naturally are, and how warm you want to stay. Some folk can ride in sub-zero conditions with just a thin baselayer and a shell, while others need three inches of fleece just to go out in autumn.
For the ultimate warmth, some baselayers have a windproof panel integrated into the front, but this can come at the cost of breathability when you’re working hard.
Baselayers aren’t just for cool or cold conditions, though. Many riders swear by baselayers throughout the year – even in the heat of summer, when a lightweight or mesh baselayer can help keep you comfortable by moving sweat away from the skin.
Long, short or no sleeves?
Assuming you want sleeves, the first thing to consider is how long you want them to be.
You won’t want a long-sleeved baselayer if all your jerseys have short sleeves. In terms of versatilty, short-sleeved baselayers will work with long- and short-sleeved jerseys but won’t be as warm in winter, and you may find the sleeves bunch up around your shoulders, especially underneath some of today’s closely tailored tops.
Whether you prefer short or long sleeves, you’re better off going for ones that use a raglan design. Raglan sleeves extend over the shoulder and all the way up to the collar. The design provides more freedom of movement for your arms and uses a diagonal seam that runs from your armpit to your collarbone, rather than circling your shoulder.
The other option is to go sleeveless. If you can’t bear to go without a baselayer on even the hottest days, a sleeveless, string-vest style garment might be the way to go.
As few seams and zips as possible
As a general rule, you want as few seams and zips as possible. The reason for that is simple: a baselayer is worn close next to your skin, so you’ll want to avoid anything that might catch, nip, rub or irritate as much as possible.
That said, you can’t avoid seams entirely so look for garments with seams in places that won’t interfere with your movements. Seams that are flatlock stitched rather than coverstitched are less likely to irritate skin, as the joint between fabric panels is level rather than lipped, so they’re the ones to seek out.
Some fabrics use contour mapping, which changes the weave of the fabric so that the structure can map to the body’s shape without the need for numerous panels and seams.
Baselayers do get smelly, so any material that delays the build-up of bacteria is a bonus. Merino naturally resists odours — wool fibres are smooth so there’s nowhere for bacteria to hide and fester.
Unfortunately, the rougher fibres of synthetic baselayers are great for breeding bacteria. Some tops use a microbacterial treatment that fights them off for a bit, but within a few rides all synthetic tops will have a… certain nasal ambience.
The answer is easy, of course – wash your baselayer(s) regularly – but it’s something worth considering if that’s not something you can do easily (on a multi-day tour or bikepacking trip, for example).
Some high-tech synthetic tops use activated carbon-treated fabric to hold in the odours and release them during the wash and dry cycle.
Some baselayers have high collars but those that do are geared more towards winter use, and may be too warm to wear in the summer months.
A lighter baselayer with a lower collar is more suitable for warmer weather and can be worn with a high-collared jersey/jacket and neck warmer when the mercury drops.
The bottom of the baselayer is just as important as the top and it’s worthwhile looking for one that extends down a little further than the typical top.
It doesn’t necessarily need to be a cycling-specific cut but a baselayer with a longer body provides more coverage, but also more material to overlap, so you’re less likely to be exposed if your jersey rides up or shorts slide down.
Meanwhile, an articulated cut will ensure the sleeves follow the bend of your elbows when you’re in an active position on the bike, rather than being left straight. This is generally comfier and prevents the fabric from riding up or bunching.
Thumb loops on long-sleeve baselayers can help keep your hands warmer in winter. They are also are great for holding your sleeves in place when you’re layering up or wearing winter gloves on top.
Caring for your baselayer
For the most part, baselayers can be thrown in the wash with the rest of your gear, but given that they’re usually made of soft materials it’s best to avoid washing in the same load as garments with Velcro, as snags can potentially ruin a baselayer.
If you’re worried about snags, consider using a wash bag (or, if you don’t have one, a pillowcase also works).
To limit a baselayer’s smelliness you may want to wash them in hot water to get rid of any stowaway stinky bacteria. But be sure to check the washing instructions before you put them in a hot wash as Merino can shrink at high temps. Also, take note of drying instructions as this can shrink baselayers too.
If you’ve got a baselayer that can’t be washed in hot water but smells like you’ve just worn it on a five-hour ride fresh out of the washing machine, Nikwax and Grangers make detergents specifically to take care of the odour-causing bacteria that can build up on your wicking layer. Assos and Rapha also make similar active washes.