Gone are the days of heavy, waterproof, puffy jackets, with tons of gizmos and gadgets that weigh you down and just get in the way. These certainly are warm, but as soon as you start doing any sort of physical activity in them, you quickly start to marinate in your own sweat.
The Layering System for Outdoor Activities
As outdoor sports progressed the clothing technology did as well. People began thinking about what to wear while cycling, hiking, backpacking, climbing, etc. Eventually, companies started realizing that it is much more efficient to use a layering system rather than 1 big piece of warm gear. Essentially, each layer provides one essential function. The layers usually consist of the following.
- Base Layer – for comfort, warmth, and moving moisture (sweat) away from the skin.
- A Mid-Layer – for comfort and warmth.
- An Insulating Layer – for warmth. Also known as a soft shell. These are the ultralight down jackets you see people wearing even around town.
- A Rain/Wind Layer – for rain and wind protection. Also known as a hard shell.
In this article, we’re going to be talking about the importance of the base layer. More specifically, we’re going to show you why Merino wool is the only base layer you should even consider. This applies to bikepacking, backpacking, hiking, mountaineering, and almost any other high exertion outdoor sport. Let’s get to it.
What is a Base Layer?
First, let’s quickly talk about what a base layer is and what the purpose of a base layer is. The base layer is the first piece of clothing you put on. It sits next to the skin, closest to your body. It is there to provide three main things:
- Wicking – Wicking is the act of the base layer material moving moisture away from the body to keep you dry and warm.
- Warmth – The base layer material traps a small amount of body heat against the body.
- Comfort – Though this is subjective, a base layer is usually supple and light, making it stretch and bend with the movements of your body. It also acts as an interface between your skin and your mid layer, as mid layers are usually not nearly as soft as base layers.
What is Merino Wool and Why is it an Excellent Base Layer?
‘Merino’ is actually a breed of sheep originally from Portugal. Today, Merinos are found everywhere in the world, but notably Australia, New Zealand, Spain, and California. The wool from these sheep has become prized because of how fine and soft it is compared to other breeds of sheep.
Advantages and Disadvantages of Merino Wool as a Base Layer
Let’s talk about why you should choose Merino wool as a base layer. We’ll also address some possible disadvantages. However, we’re still convinced the positives outweigh the negatives by a longshot.
- Wicking – This is the act of drawing liquid away through capillary action. In layman terms, it’s the material’s ability to move moisture away from the body. Wool is great at doing this. Cotton, on the other hand, is terrible at doing this. That’s why a wet cotton shirt takes forever to dry and makes you feel cold when it’s wet. Synthetic materials like polyester and nylon are also good at wicking moisture.
- Odor-Resistant – Sure, you’ve probably seen plenty of clothing items that claim to be odor-fighting, only to find out that they stink after the first few uses. Merino wool is nothing like those. Why doesn’t Merino wool smell? First, it is able to transport moisture vapor away from the body quickly, which means that vapor does not have time to condense into a liquid in the wool itself (though a small percentage does). This lack of moisture makes it harder for odor-causing bacteria to find a place to grow. Second, any vapor that does turn into liquid is moved quickly outward toward the outside of the wool fabric, where it can evaporate quickly. There are thousands of stories of people wearing their Merino wool layers for days, even weeks, before they start to smell and have to wash them. Smell is the one reason folks tend to stay away from polyester and nylon base layers.
- Warmth – The structure of wool gives it an ability to trap air. It turns out air is one of the best insulators that we can use to our advantage in the outdoors. Not only is wool naturally warm, it also has an incredible ability to stay warm even when it’s wet. This is not something you’ll find with polyester or nylon, and certainly not with cotton, which actually cools you faster when it’s wet.
- Cooling – This one is a little less intuitive but it has to do with breathability. You’d think that something that is so good at keeping you warm cannot possibly also keep you cool. But it’s true. And it’s once again thanks to its ability to wick moisture away. When you sweat a lot, the Merino wool fibers will absorb a small amount of this moisture. As your body heats up, and as the fibers move the moisture away from your skin and toward the outer surface of the fabric, it begins to evaporate. Evaporation allows for a transfer of heat and so your body is able to move the heat away in order to cool itself.
- Non-Itchy – Let’s make one thing clear: Merino wool is not the same as traditional wool. Merino wool fibers are much smaller and softer than standard wool, making them smooth and comfortable next to the skin. Because these fibers are so small and fine, they are more flexible and stretchy, which makes these garments conform better to your body and increase overall comfort.
- Sun Protection – Merino wool naturally protects against harmful UV rays. This is great news for those of you who aren’t fans of sunscreen. A long sleeve Merino wool shirt can be worn in warm conditions, keep you cool, and protect you from the sun at the same time.
- Dries Quickly – When compared to synthetic garments of equal weight (meaning material thickness), most Merino wool dries just as quickly.
- Requires Less Washing – Because Merino wool is odor-resistant, you can get away with washing it less (and no one will notice). That doesn’t just save you some money in terms of utility bills, but it also means your clothes will last longer.
- Durability – Thin and lightweight Merino wool pieces can be more fragile when compared to lightweight synthetics. For this reason, it’s best to hang dry them. However, manufacturers have found a great way to make Merino wool more durable. See the section on Merino Wool Weights below for information.
- Can be More Expensive – As with everything, you get what you pay for. More expensive 100% Merino wool pieces will be more expensive than blends that only have 15% wool. A piece with 100% Merino wool isn’t necessarily the best for bikepacking though, due to potential durability issues. See the description of ‘corespun‘ pieces below.
Merino Wool Weights
Merino wool essentially comes in three “weights”. Think of the “weights” as warmth levels. Companies oftentimes use numbers to describe the weights (150, 200-250, 250-300 weight).
- Lightweight or “150 Weight and below” – Use in hot to warm temperatures.
- Midweight or “150-200 Weight” – Use in warm to cool temperatures.
- Heavyweight or “250 Weight and above” – Use in below freezing temperatures.
Merino Wool Blends
Often, companies will market a piece of clothing as “Merino wool” when it only contains a small percentage of the stuff. You want to avoid these. For example, socks with 15% Merino wool and 85% nylon or polyester will stink just as much as if there was no wool in them at all.
Focus on clothing that has at least 60% Merino wool also called ‘corespun’.
With lightweight Merino wool clothing, durability can be an issue. To help with this, manufacturers have started producing pieces made of 60-80% Merino wool and 20-40% nylon. Look for this in the product description. These clothes are called ‘corespun‘ and involve spinning the wool around a nylon core. In our opinion, these are the best pieces because they retain all the advantages of 100% wool, but have drastically increased durability. This construction is especially common in socks, which need to be durable.
Merino Wool for Bikepacking – A Summary
So, why Merino wool for bikepacking? Quite simply for all the reasons listed above. But let’s recap:
- A layering system is key when choosing the clothes to bring on a bikepacking trip.
- A base layer will enhance comfort, ability to stay warm, ability to cool off, and the ability to not smell!
- Merino wool is the ideal material to wear for all these things.
- For warm temperatures, choose lightweight Merino wool (100-150 weight).
- For cool temperatures, choose midweight Merino wool (150-250 weight).
- For cold temperatures, choose heavyweight Merino wool (250 weight and above).
- Look for clothes with a high percentage of Merino wool in their composition. Something with more than 60% Merino wool is good.
- For socks, look for Merino wool and nylon blends (‘corespun’). This makes socks more durable.
- For lightweight (100-150 weight) Merino wool pieces, look for Merino wool and nylon blends (‘corespun’). This will keep these notoriously fragile pieces in one piece for much longer.