Base layers. Everyone is talking about them. But is everyone wearing them? And if so, should you wear one?

In this article, I’ll dive into what a base layer is, when you might wear a base layer, and why you would wear a base layer.


What Is A Base Layer?

A base layer, by simple definition, is the first layer of clothing you wear against your skin before you put on any other layers. It is the “base” of your outfit.

Generally, when someone says “base layer,” they mean an undershirt. Other garments (underwear, tights, etc.) are rarely considered base layers, but sometimes certain compression shorts and/or long underwear fall into the base layer category.

For the sake of simplicity, in this article I’ll be talking about base layers for cyclists, which will be undershirts. Typically, a good base layer will be made of high-tech synthetic fabrics (or wool,) and it will wick sweat away from your body. Sometimes they are like loose fit t-shirts, some are tight, some are compression fit, some are thin, and some are thick.

I suggest either a tight fit or compression fit base layer. To do its job, a base layer should be snug against your skin. A loose fit base layer will just bunch up, rendering it uncomfortable and unable to function very well.

The thickness of the base layer will depend on when you wear it…


When Do I Wear A Base Layer?

When I think of layering, I think of wearing multiple layers in cold or changing weather conditions so that I can always stay comfortable. However, you can wear a base layer in just about any weather conditions year-round.

Cold days, hot days. Summer, winter. Training rides, races. Road, mountain. Whatever.

There are arguments for all those times to wear a base layer. Hence the next section, “why wear a base layer?”


Why Should I Wear A Base Layer?

That’s a good question. In this section, I’ll analyze all the reasons you might wear a base layer.

Base layers keep you warm in cold weather.

This is the most popular reason right here. You can wear a base layer in cold weather to help keep you warm.

It does this in two ways. First, the base layer provides an extra layer of insulation. Second, it will wick sweat away from your skin, so you stay dry.

Base layers keep you cool in hot weather.

On warmer days, you can wear a base layer to stay cooler. That’s the promise at least. Somehow the sweat evaporating off the base layer is supposed to cool your body. But really, sweat evaporating straight off your skin would keep you cooler.

I say this idea is pure marketing; companies are simply trying to sell more base layers!

I mean, some shirts are even marketed as promoting “air to skin contact.” What’s that mean? How can you get more air to skin contact than having the air hit your bare skin?!

Pro riders wear base layers.

I remember seeing ads and/or editorials talking about pros wearing base layers. Usually this was tied into the “base layer keeps you cooler in the heat” reason mentioned above.

Then I’d watch some pro cycling on TV, like a mountain stage of the Tour de France on a hot day, and maybe a couple riders out of the bunch were wearing base layers. Most wore just a jersey and had it fully unzipped at that. That should tell you something.

And for the pros that were wearing base layers, it could have been for a different reason, like road rash prevention and/or compression fit benefits. Or perhaps they’re paid to wear them. They are sponsored after all!

Compression gear increases performance.

A compression base layer is a different ball game. In this case, the base layer is worn for the benefits of compression clothing, regardless of the weather conditions.

Some research shows that compression garments (Under Armour, SteelStretch, etc.) can delay muscle fatigue and increase performance when worn during exercise. I do like the feel of some compression shirts, but since cycling is primarily a lower-body activity, I wouldn’t worry too much about these benefits.

A dry base layer is more comfortable than a clammy cycling jersey.

I found this reason mentioned on another cycling website and found it so senseless that I couldn’t forget it.

The comparison is between a dry base layer and a wet, clammy cycling jersey. Obviously the dry layer would be more comfortable, but how is this situation realistic?

First of all, your cycling jersey should wick sweat away from your body. If it doesn’t, get a new jersey!

But let’s say you have a nice base layer under your jersey. The base layer will wick your sweat away from your body, but then it must transfer the sweat to your outer layer (your jersey) for evaporation.

Assuming your jersey gets sweaty and stays sweaty/clammy, the base layer can no longer transport your sweat to the already saturated jersey. So you now have a clammy base layer under a clammy cycling jersey! How is that more comfortable?!

Base layers can save your skin from road rash.

This is the reason that convinced me to purchase an undershirt before I started racing.

The theory is that, if you fall off your bike and slide or roll, your jersey will catch the asphalt, but your undershirt will keep sliding within the jersey. And sliding on an undershirt feels marginally better than sliding on bare skin.

Obviously, this won’t save you from everything. It definitely won’t prevent broken bones. And if the crash is big enough and you slide far enough, any road surface is going to eat through a couple layers of spandex in no time. (That’s why motorcycle racers, longboarders, etc. wear leathers!)


Base Layers: My Recommendation!

While there are quite a few reasons being thrown around, there are just two main times when I’ll wear a base layer.

First, when it’s cold and I want to stay warm and dry.

Wearing a base layer in cold or wet weather has always helped me stay warm. I love my fleece and wool undershirts (very warm and cozy,) but I also like my SteelStretch Ice undershirt since it’s tight and thin (so it easily fits under anything.)

Second, when I am in situations that could lead to crashes.

The ‘why’ for me comes down to reducing friction in a crash. I’m not expecting miracles, but a slightly reduced risk of injury is worth wearing a base layer.

Since I wear an undershirt during races, I’ll also wear one during training. Which means I’m bound to wear undershirts on warm days. And yeah, they’re more comfortable than some of my cycling jerseys. But I’m not expecting them to keep me cooler!

I suggest you buy at least two base layers.

First, get a thin, short sleeve base layer with a tight fit. White is preferable. Compression fabric is optional. This is your summer undershirt, (but it can also be worn in cooler temperatures, because any little bit helps.) This is mainly to help prevent road rash and keep you comfortable under any not-so-comfortable jerseys.

Then, get a thicker, long sleeve base layer. I suggest merino wool because it’s the best material ever found, but there are some fleece undershirts that are nice, too. This should also be a fairly tight fit. This will be your cold weather base layer, and it will increase your riding comfort much, much more than the summer undershirt!

If you buy more undershirts, I recommend stocking up ones designed for cooler weather.

But really, just go ride your bike!

You may also like
  1. I’m a cyclist and fair skinned. I live in LasVegas and I always wear a long sleeve base layer with UPF50 rating. Much better than sunblock

  2. Well this might be a stupid question, but…

    I’m going to Helsinki next week

    I’ve bought synthetic baselayers/ long underwear but not sure they will work properly as on top I’ll wear a cotton shirt, wool jumper and parka/ down jacket, bottom will be jeans.

    Will the baselayer still work or is it pointless?

    Peter Ting-Saelges

    • @Peter

      Not a stupid question at all. It’s a very common situation, but there’s no “one size fits all” answer.

      In general, yes, the base layers were a great idea! They’ll still work.

      The only catch is that there will be limits. You could reach a situation where the outer garments start to limit the effectiveness of the base layers. It will depend on how much you’re sweating and in what time span. Your cotton shirt might end up soaking wet. But on the bright side, your skin should still be dry and free of any uncomfortable chafing thanks to the base layer!

      Enjoy your trip!

  3. You are very smart/experienced!! I am not always on the ball, but I have found too that on hot days going without a base layer allows my sweat to go from me right through the jersey so I never really seem like I am sweating even though I ride fast.

    Big difference when I listened to the thin base, mid layer and outer layer advice when riding in the cold. The thin base layer, despite being polyester got all wet and kind of clammy.When I skipped the thin base layer and went with what would normally be a mid layer thin fleece shirt under a long sleeve fall jersey I didn’t seem to sweat…guess it evaporated better!

Leave a Reply