What’s Inside a Hiking Shoe?

03 October 2022

Your guide to finding the perfect boot.

Whether it’s a couple of hours or several days, we want to make sure your feet stay happy from trailhead to summit. Pick your passion below:


Backpacking – You’re in it for the long haul, sleeping under the stars on this multi-day trip. You’ll need a heavy pack to carry all of your gear (13kg ) and will need some serious hiking boots with support.


Day Hiking– You can’t quite commit for a multi-day adventure, but still want to escape outside for the day. You may want to carry a mid-weight pack (under 13kg) to hold water, snacks or a meal and extra layers, so make sure you have something sturdy on your feet but not so bulky they weigh you down.


Lightweight Hiking – You only have a couple of hours or want to change up your daily workout routine for one on the trail. You’re looking to take only the essentials and need your gear to be lightweight, versatile and ready for any adventure.


THE JOURNEY: Types of Hiking Boots and Shoes

While the insole is nearly invisible, few things play a greater role in the way a shoe performs. We design our insoles around the way a shoe will be used – a stiffer sole provides the stability you need when carrying heavy loads through rocky, uneven terrain; lighter and more flexible insoles enhance your agility while speed hiking. By using different materials and configurations – like steel shanks or different lengths and thicknesses and tapered injected nylon – we can fine tune the flex of each insole so that it’s just right for its intended purpose. Use the Merrell Flex Index as a guide:



1. Boot Height: How low should you go?


Low Cut – Looking for versatility? A low cut hiking shoe is your go-to for travel and quick day trips. They’re lightweight and very packable. Let the adventures begin!


Mid Cut – Carrying a pack & headed out for more than a couple hours? Go for the mid cut boot. It will offer better ankle support and protection from dirt and debris.


2. Boot Anatomy: Materials and Construction

There are three main parts to the construction of a shoe: Upper, Midsole and Outsole:


The Upper – You have two main material choices when selecting a hiking shoe upper: leather or synthetic


Leather – The best for durability, protection, strength and comfort. The type of leather can affect the aesthetics & waterproof capability.


• Full Grain Leather – This type of leather is smooth & shiny. It takes on waterproof agents very well. The thickness of this leather and tightly knit fibres give it exceptional durability.
• Reverse Full Grain Leather – This is the strongest leather due to its thickness. The tough outer layer stands up against abrasions.
• Nubuck Leather – This is a type of full grain leather that has been buffed as to not show imperfections in the hide. Reacts well to embossing, pressing. Various waterproof agents will work, but may result in a darker appearance.
• Split Leather – This is the split side of the hide after the upper full grain portion has been detached. This option is the most affordable available. The fibres are slightly looser than full grain leather to provide a softer feel. This leather can also be oiled, waxed, & buffed to improve appearance or water resistance


Synthetic – This is a man-made product that can be used for the construction of the upper in shoes.


• Ventilated: This option is best for warm climates & dry conditions. The upper is ventilated & ultra breathable, but still durable to keep out dirt and other trail debris.
• Waterproof Synthetic Leather: Looking for a vegan option for your shoes? Our synthetic leather functions very similarly to traditional leathers. Water resistance & durability are not lost with synthetic leathers. You can still expect exceptional performance on the trail.


Waterproof Linings – GORE-TEX® is a common waterproof membrane. Merrell also offers options with our own proprietary waterproof that is often a lower cost.


There are 2 ways a shoe can become waterproof:


• Full bootie construction: this is like constructing a waterproof membrane shaped like a sock into the footwear.

• Seam-sealed construction: This process includes taping pieces of waterproof membrane together in the shoe to make it completely waterproof.

Check out Merrell’s Waterproof Hiking Products for Men and Women.


Insulated Linings – When the temperatures drop, it’s important to have proper insulation. The materials and fibres capture body heat and reflect it back. This creates a thermal micro-climate inside your shoe.


The Midsole

This is where the comfort and stability of the shoe live. It’s below the footbed and above the outsole. The area below highlighted in orange is the midsole.



Air Cushion

Air cushion is found exclusively in Merrell footwear. This part of the shoe absorbs shock and adds stability. The orange disc shown below is the air cushion.



The Outsole

Most hiking outsoles are made from rubber and are classified by the level of stiffness. We recommend using the FIST scale (above) to determine which type of outsole you need.


Lug Pattern – The lug pattern and depth on the outsole helps your foot move through the dirt, trail and ground. The deeper the lugs, the greater the traction will be.


Heel Brake – A “heel brake” is a raised heel zone that reduces your chance of sliding & falling on steep descents. Not all hiking footwear has this, encouraging the use of your foot and your toes’ natural strength to prevent sliding or slipping on the trail.



Vibram® is the world leader in high performance rubber soles and compounds for outdoor footwear. It is used in many of Merrell hiking products. Look for the yellow logo.




The three parts of the shoe – upper, midsole and outsole – need to be joined together. There are two predominant forms of how this is done:


Strobel Construction – Currently the more popular type of construction, Strobel construction secures the upper and outsole by using heat to weld materials together, or with adhesives. This creates a very flexible boot or shoe, and often less bulk.


Norwegian Welting sews the upper directly onto the outsole. This creates a very sturdy, although sometimes very stiff, boot.


3. FIT: If the Boot Fits…Your feet will thank you!


Design Factors


Last – A last is a piece of wood, metal or synthetic material roughly following the shape of the foot and acting as a form on which a shoe or boot is made. It is the foundation or ‘vital centre’ of all of Merrell’s footwear. Through years of testing, Merrell has designed lasts that are specific not only for men and women, but for different kinds of outdoor activities. Our shoes should fit snug in the heel and precise over the instep to keep feet from sliding forward. You should have plenty of toe room and be able to wear mid-weight hiking socks or a combination of a light liner with a mid-weight sock.


Women’s Specific Fit – Since the beginning, Merrell has used separate lasts for men and women. Our women’s lasts have always taken the following details into account:


• Women’s feet are narrower than men’s at the ball of the foot, the Achilles tendon and the heel.
• Women have proportionally longer toes than men.
• Women have a higher instep and arch.
• Women’s calf muscles are longer, carrying farther down into the boot.



Tips for a Proper Fit


Merrell is known for footwear that fits right out of the box. Make sure your shoes or boots fit at the time of purchase. You will want a snug fit across the arch of your foot & in the heel and room in the toe box. Here are some things to look for when finding the right fit for your shoe or boot. It’s always best to do a couple test hikes before you head out for the main adventure.



Front to Back – We design our boots to fit like your street shoes. Try the boots on with the socks you would normally wear on the trail. Stand up and push your toes forward so they touch the front of the boot. Make sure you can slip one finger into the space behind the heel. If you can’t do this, you should try the next half size larger. For boots that will be used carrying a moderate to heavy load, a full finger space is highly recommended as your feet may swell with the weight of your pack.


Side to Side – To lace your shoe, tap your heel back in the heel cup of the boot. The boot should feel snug across the ball, around the instep, and in the heel. The arch should be comfortably supported and the toes should have enough space to wiggle and curl. It is important that the instep is snug. This will help give internal control and prevent toes from sliding forward when you go downhill.


Check the Fit – To check the fit in the heel, test the boot on an incline. The heel should lift a maximum of ½ an inch. In a stride, your foot bends at the ball, and heel tries to pull away from the boot. Because of our precise fit, the upper follows the heel. This prevents the slipping and sliding that eventually causes blisters. To check the fit in the toes, walk down an incline. Your toes should not jam in to the front of the boot, but gently tap the front of the footwear.


A Note on Width – The standard/medium width of Merrell footwear is a Men’s D and a Women’s B. If the foot feels too loose or too tight in this width, you may want to adjust the overall volume of the fit. Merrell’s Men’s & Women’s custom fit system of footbeds allows you to modify the volume and width to fine tune the fit of our footwear. While this works for some people, in some cases a standard/medium width may not fit.  In these situations, a wide is recommended.


When we designed the fit of our footwear, we considered sock thickness. In choosing socks for Merrell footwear, the following guide should apply:


Hiking Boots – Heavyweight, thick, dense socks with or without a liner sock.

Light Hiking Boots or Multi-Sport Shoes – Light or medium-weight dense socks.



Did you find this informative? Check out How to Lace Hiking Boots.




Women’s Moab Mid GTX

Men’s Moab Mid GTX