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Fixing My Climbing Shoes Part One

Crap, this sucks! I’ve noticed that there’s something wrong with one of my climbing shoes. There’s a hole in it. The rubber has worn through, and you can see a little bit into it. The rubber on the other looks worn too. Not good.

A hold in the rand of my left climbing shoe.

How does this happen? Well, like everything else, stuff breaks down when used frequently. The same goes for climbing shoes. Despite how durable the rubber is, it will wear through over time.

Sticky, Sticky Rubber

According to Climbing Magazine writer Sam Lemonick in his article "The Science of Sticky Rubber", “Rubber refers broadly to a class of tough, elastic materials so ubiquitous it is difficult to define. About 40 percent of the rubber we use is latex, made naturally by rubber trees. Lemonick states that “the general idea behind “sticky rubber” is that it’s soft, so it forms around the smallest of divots and bumps, creating more surface contact between rubber and rock and thus offering greater friction. Sticky rubber deforms in this manner hundreds of times on any given climbing day and bounces back to the original shape, but the softness also means it will wear out faster than the rubber on hiking boots or sneakers.” So, this is good and bad for climbers.

What goes into the rubber besides latex, butadiene, chloroprene, and others, no one knows. That’s because climbing shoe companies keep the rubber recipe under lock and key. There’s a science to creating shoe rubber that I wouldn’t have thought about until I read Lemonick’s article. If you’re interested in learning more about the subject, you should check it out.

Companies design specific types of rubber for shoes. For example, Vibram makes XS Edge and XS Grip 2 for La Sportiva and Scarpa. My Otakis are from La Sportiva and have the XS Grip 2 rubber. Five Ten’s Mi6 is softer than the classic Stealth C4 rubber. However, Five Ten also uses Hf, Onyxx, and Mystique as well for their shoes. Evolv has Trax XT or eco-Trax on their shoes.

Thick or Thin?

Something that also affects the wear of your shoes is the thickness of the rubber on them. Thinner rubber (3-4 mm) is softer and more sensitive, which allows you to get a better feel for the rock. It’s great for shorter routes, bouldering, and smearing for slab. Of course, the drawback to having thinner rubber is that it wears out faster, especially if you climb frequently.

Thicker rubber (up to 5.5 mm) holds up longer and provides extra support on long routes so your feet won’t tire prematurely. You won’t get the same amount of sensitivity, but if you climb mostly long, vertical, technical routes, you’ll want the edging power and durability of climbing shoes with thicker rubber.

Until you’ve built up strength in your feet, softer/thinner rubber soles will make your feet tired and sore. Thicker rubber, on the other hand, gives your feet a bit of a break—and last a little longer—while you improve your footwork. Sloppy footwork is a considerable cause of rubber wear.

Anatomy of a Climbing Shoe

Diagram of exterior climbing shoe parts from one of my Otakis.

It helps to know what the parts of a climbing shoe are. From Switchback Travel writer Chris Kalman, he states which pieces of the shoes climbers should be familiar with are:

Last writer Stewart Green states that shoemakers build climbing shoes around what’s called a last. A last is a three-dimensional form in the shape of the human foot and includes the foot's anatomical information. It determines how a shoe fits the foot as well as the size and shape of the footbed, toe box, and heel cup. They construct shoes around the last: with fabric, leather, and rubber cut and then glued and sewn to the shape of it.


The sole is the rubber exterior on the bottom side of the shoe. This part is where the contact between your feet and the rock happens. There are scores of different rubber blends used for shoe soles, each with varying degrees of stickiness and durability.


The midsole is what sits on top of the rubber sole of the shoe. Its job is to provide rigidity to the shoe, as well as to create and maintain the shape of the footbed. Climbing shoes undergo a lot of pressure, so the midsole is usually composed of a highly flexible, resilient, and thin plastic laminate.


The footbed or insole is the part of the shoe that your foot physically stands upon. It covers the midsole and usually is composed of a durable synthetic leather or leather material.


The rand is on the edge of the sole and wraps the edge of the forward half of your foot. In a climbing shoe, it’s responsible for sucking the foot in tight over the footbed and reinforcing the edging platform of the sole. The outer part of the rand on climbing shoes is composed of some blend of sticky rubber.

Heel/Heel cup

All climbing shoes have some molded heel that’s shaped to fit a typical heel. Some have a highly molded cup-like shape that supports the heel while driving the toes forward. Internally, the cup has the same material as the footbed. Externally it’s composed of sticky rubber.

Toe Box

The toes should be tightly supported in the front of the shoe (the toe box) as much as can be done comfortably. With climbing shoes, the goal is eliminating dead space, and the toe box is no exception. It should be tight from top to bottom and side to side.


The upper is the part of the shoe that rests upon the top and sides of your foot. Uppers typically are from a soft, durable fabric composed of either high-quality leather or synthetic leather materials. Most of the upper tends to be free of rubber and should be comfortable plus wick sweat well.

Now that you’re more informed about how a climbing shoe is composed, in part two I’ll cover what to look for when caring for your shoes. Plus, when you should send your shoes in for mending. Until next time, happy bouldering!