It’s funny how something as seemingly simple as the rubber on the bottom of your shoe can make such a monumental difference, isn't it? For anyone who’s ever laced up a pair of climbing shoes, you know that feeling – that almost supernatural grip that lets you trust your feet on the tiniest of edges or the slickest of slabs. But have you ever stopped to wonder how we got here, from clunky leather boots to these high-tech, sticky marvels?
Think back, way back. Climbing wasn't always the accessible, dynamic sport it is today. Forty years ago, a 5.12 or 7a climb was the stuff of legends, reserved for the absolute elite. Now, while still a significant achievement, it’s a benchmark many dedicated climbers can reach. A huge part of that evolution, beyond training and technique, has been the gear. And at the heart of that gear? The humble climbing shoe, and more specifically, its rubber sole.
Our journey starts with mountaineering boots from the early 1900s. Imagine lugging yourself up a mountain in shoes made entirely of leather, soles and all. They were heavy, not exactly waterproof, and often studded with nails for grip on mud and snow. Functional, sure, but for the delicate dance of rock climbing? Not so much.
The real game-changer arrived with Charles Goodyear’s discovery of vulcanization in the mid-1800s. Before that, rubber was a bit of a diva – sticky when hot, brittle when cold. Vulcanization tamed it, making it elastic and durable, paving the way for rubber soles in footwear. You might even recognize the name; the tire giant Goodyear is named in his honor.
Still, early climbers were using modified mountaineering boots, which were cumbersome and lacked any real sensitivity. It wasn't until the 1930s that pioneers like Pierre Alain in France started thinking, “There has to be a better way.” Alain, a keen boulderer himself, realized the limitations of existing footwear. After trying out hiking shoes with marginal improvement, his obsession led him, in 1947, to collaborate with a local shoemaker. The result? The PA boot, the world's first shoe specifically designed for climbing. It was a hit, and a few years later, Edmond Bourdonnaau acquired Alain's venture, refining the design and renaming it the EB boot – marking the first time a brand name appeared on a climbing shoe.
Fast forward to the 1970s, and a Spanish company named Calzados Boreal S.L. embarked on a decade-long project to develop the ultimate climbing shoe. Their focus? A specialized climbing rubber that offered unparalleled friction while balancing durability and stickiness. This relentless pursuit led to the Boreal Fire in 1979, a shoe that truly revolutionized climbing. Climbers reported immediate improvements in their ability, with some even claiming they could climb a full number grade harder. The Boreal Fire’s rubber sole was the blueprint for what we see today, even if it still retained a mid-high cut reminiscent of mountaineering boots.
The legend of the Boreal Fire spread like wildfire. When Gallegos brothers brought these shoes to Yosemite in the early 80s, climbers like the legendary John Bachar were captivated by their sticky rubber. The demand was so intense that a batch imported to a Yosemite outdoor shop sold out in just two hours, purely by word of mouth.
Since those early days, climbing shoe design has seen massive advancements, but the core technology remains the "sticky rubber" – a carefully guarded secret blend of chemicals, unique to each manufacturer. Among the leading players in this high-stakes game are:
Vibram Rubber
Vibram’s story begins with tragedy. In the 1930s, Vitale Bramani lost six friends in a mountaineering accident, attributing the poor quality of their footwear as a contributing factor. His subsequent development of a high-performance, durable rubber for challenging terrain made mountaineering safer and established Vibram as a leader. It wasn't until 1988, however, that they introduced the Vibram Grip series, specifically for free climbing.
- XS Grip: This is a high-performance rubber known for its semi-stiff nature, offering excellent friction on various rock types. It's a favorite among manufacturers like Tenaya, Red Chili, and Ocun, and has been a go-to for elite climbers like Daniel Woods and Alex Megos.
- XS Grip 2: An evolution of XS Grip, this compound offers enhanced grip and durability. It's softer than its predecessor, excelling on overhanging routes while maintaining good performance on small edges and smears. It's commonly found on high-end shoes from La Sportiva (Solution, Miura, Skwama) and Scarpa (Instinct, Vapor, Drago).
- XS Edge: Noticeably harder than XS Grip 2, XS Edge provides superior durability and support, making it ideal for edging – that crucial technique of standing on tiny rock protrusions. It's a popular choice for entry-level shoes and for granite climbing, especially for slab and crack climbing. La Sportiva's TC Pro, a favorite for Yosemite granite, features this rubber, as does Evolv's Yosemite Bum.
So, what's the key difference between XS Edge and XS Grip 2? Think of XS Edge as the precision tool for small holds, offering stiffness and stability, perfect for granite and edging. XS Grip 2, on the other hand, is the more versatile, softer option that enhances overall climbing performance, making it a great choice for those past the beginner stages.
It’s a fascinating journey from leather boots to these specialized sticky compounds. Each rubber formulation is a testament to innovation, pushing the boundaries of what’s possible on the rock. And the quest for the perfect grip continues, promising even more exciting developments in the future.
