The Stickiest Climbing Shoe Rubbers

Which rubber is the stickiest on climbing shoes? A study shows some rubbers are sticky than others. Photograph copyright Stewart M. Green

Climbers have been debating the stickiest climbing shoe rubber since the first smooth-soled climbing shoes were imported from Europe to the United States in the 1960s.

Rock climbers wear specialized shoes to increase their climbing performance. Sticky rubber helps climbers' shoes mold more easily to the rock, allowing them to climb harder and higher. For this reason, serious climbers are always looking for shoes with the stickiest rubber.

The Composition of Climbing Rubber

Natural rubber is an organic compound harvested from rubber trees. Because of its molecular structure, it has unique properties, such as the ability to bend and mold itself to different surfaces. When rubber makes contact with a surface, such as the holds on a climbing wall, it generates friction. Without this friction, climbing would be much more difficult. But natural rubber isn't perfect. It generates different amounts of friction at different temperatures, making it unreliable—not something you want in a climbing shoe.

Since the 1960s, natural rubber has been largely replaced by synthetic rubber, which is produced using a variety of proprietary formulas. The climbing shoes sold today all include some form of synthetic rubber. These climbing rubbers are usually not vulcanized as much as other rubbers, so they are still soft and sticky and perfect for climbing.

Study of Climbing Rubbers

For 50 years, the question of which climbing rubber was the stickiest was a matter of great debate. There was little empirical data to help climbers make informed comparisons between the different climbing rubbers on the market. Now, that debate is over. A study, published by Spadout.com and conducted by climber and physicist Steven Won at Northwestern University's Department of Physics and Astronomy, analyzed nine popular climbing rubbers, including Evolv TRAX XT-5 and La Sportiva FriXion RS.

Climbing shoes with each rubber were purchased and cut apart, and samples of each rubber were tested to determine their  “coefficient of friction” on both a granite hold and an artificial hold.

The Stickiest Rubber

The results were surprising. The study’s overall winner was Evolv TRAX XT-5, with La Sportiva’s FriXion RS a close runner-up. The 5.10 Stealth C4 rubber came next to last, just above Mad Rock's Formula #5. Brian Shelton of Front Range Climbing Company wasn’t surprised. “I’ve always used my Evolv shoes on my hardest face routes because they’re the stickiest," he said. Other climbers may have to switch over and see if the sticky rubber helps them climb harder.

Lab Tests vs. Real World Results

This study, of course, should not be the final word when it comes to determining the best rubbers. The study was done in a lab with controlled temperatures and a limited load on the rubber samples. Further testing needs to be done in real-world conditions. As is often the case, trial-and-error may still be the best way for climbers to determine which climbing shoe rubber is right for them. What works best in an air-conditioned gym may not be the same as what works best on the face of a desert cliff.