Climbing shoes are made from a combination of leather (natural or synthetic) and nylon. Stiffer shoes may contain a thin insole. Very close fitting shoes (slippers) skip the insole to provide more sensitivity. Linings prevent the leather from stretching or bagging out. The material between the outer sole and insole (the midsole) can be a thin plastic, fibreglass, or nylon insert, or hardened natural "pulp" fibre. Finally, the sole and rand are made from a sticky rubber compound. This rubber is a closely guarded proprietary secret and every manufacturer lays claim to the ultimate "sticky" rubber recipe.
Things to consider when buying rock climbing shoes:
For most people, the ideal climbing shoe can handle different types of climbs. Designed for all-day comfort, long climbs, and varied vertical terrain, these shoes are the best solution for a climber who only wants one pair. All around shoes should fit close (but not tight). Look for a shoe with a firm, supportive sole and a wide, flat profile. Avoid shoes with a radical downward curved shape that curls your toes. Lace-ups provide a more versatile fit, slip-on shoes tend to be tighter and less supportive. After a short break-in period, a good all around shoe should fit like a tight running shoe.
Experienced climbers may want a shoe designed specifically for the terrain they plan to tackle. For extremely steep or overhanging routes, look for climbing shoes with a pointy toebox and an aggressive down-turned or hook-lasted shape. Shoes with a down-turned shape are built with a pre-tensioned, or "slingshot" rand that drives the foot forward and centres your weight over the big toe. They suit precise foot placements or heel-hooks on gnarly overhangs. If this sounds like you, consider shoes with a thin, soft, sensitive sole. Slippers, or shoes with hook-and-loop closures are also good because they can be worn very tight and removed quickly when you're through.
Dedicated crack climbers should look for a climbing shoe with a high rand and a stiff midsole that will reduce the pain of camming your feet into hand-width cracks. Climbers who are negotiating finger-width cracks might opt for slightly softer shoes with a narrow profile that allows you to twist a toe into a thin seam. Avoid shoes with a radical down-turned shape; they tend to curl your toes, which can generate more power on very steep routes, but can be exquisitely painful when jamming a crack.
A well-fit, comfortably snug shoe can mean the difference between a sublime climbing experience and a foot cramping endurance festival. Climbing shoes are constructed on anatomically correct lasts. Meaning, they are contoured to fit an average size foot, of average width, with perfect arches and shapely toes. Unfortunately, your feet are unique. It's best to try several brands and styles to find a manufacturer's last that best matches your foot.
Sadly, there is no definitive answer to this question. Rock climbing shoe volumes have three basic characteristics: they allow your toes to lay flat, slightly bend your toes, or push your toes down into the front. Ideally, a shoe should be snug and glove-like without extra space at the toe or slippage in the heel – without being cruelly tight.
All climbing shoes will stretch a little bit (unlined shoes will stretch more) and conform to your foot. However, a shoe will not get longer. Too short is too short.