Climbing Bolts and Anchors
Bolts are small, permanent anchors fixed in the rock at regular intervals. They offer dependable protection and can reduce the chance of a very long, potentially severe fall. Before the use of climbing bolts, rock faces could only be climbed if they could be protected with traditional gear. This meant that sheer faces without places to put reliable pro remained untouched. The introduction of permanent climbing bolts changed the perception of what could be climbed and gave rise to the discipline known as sport climbing.
However, the popularity of sport climbing has spurred debate over the environmental, social, and ethical impact of bolted sport routes in public recreation areas. Be aware that the use of bolts can be a controversial issue in the climbing community. When thinking about placing bolts, respect the ethics of the locals and those who first discovered the routes.
Types of Climbing Bolts
Bolts and hangers sold at MEC are made of stainless steel. It offers substantial resistance to corrosive agents found in natural environments, including water, salt, and acid rain. The long-term suitability of stainless steel is of some concern in areas such as Thailand, but in Canada it has been broadly accepted.
Currently the most popular type of bolt. They are hammered into a pre-drilled hole, then as the head of the bolt is tightened, a collar expands. Expansion bolts are essentially industrial masonry fasteners used for climbing applications. Best used in hard rock such as granite, quartzite, or hard limestone.
Glue-in bolts create a strong coupling between the bolt and the surrounding rock. The glues are so strong that often the surrounding rock will fail before the bolt-rock bond does. Adhesives penetrate the rock forming a bond that reinforces fractured or layered rock, seals the hole, and protects the bolt shank from the elements. These are generally placed in softer rock such as porous limestone or sandstone.
The disadvantages of glue-ins is that they are more expensive than expansion bolts, take a full day to cure, and can't really be placed on lead. They require considerable knowledge and patience to place correctly. Proper application of the industrial resin is crucial to a sound placement and the drilled holes must be completely free of debris for a proper bond to take place.
Climbing Bolt Hangers
Bolt hangers are loops of metal attached to drilled bolts. Glue-in bolts have a ring at the head that replaces the need for a hanger. Climbers clip them with a carabiner when leading a route, and at belay and rappel stations.
A well placed bolt in good condition, in good rock, rarely fails. But if a bolt does fail, it occurs from overtightening (snapping) or inappropriate placement that destroys the rock around it causing the bolt to shear or pull out. Under extreme and highly unusual circumstances a loaded bolt may flex under load and crush the surrounding rock. With the support of the rock decreased, the bolt will continue to bend and develop a prying action that ultimately pulls the bolt out. This can be avoided by using large diameter bolts that resist bending and have a greater area of contact with the rock. The accepted minimum standard for sport climbs is 3/8in or 10mm. These meet the CE standard shear strength of 25kN.
You can reduce the chance of rock failure (a concern with soft stone and rock with a flaky or crumbling surface) by using the longest bolt possible. Using long bolts increases the surface area in contact with the rock and improves holding power.
An anchor is a secure attachment point at the top of rock or ice pitch. The anchor (also called a station) may be a natural feature such as a well-rooted tree, block of rock, horn, or chockstone. It may be a removable anchor made with several pieces of climbing gear or ice screws. On a popular route at a developed climbing area, the anchors are usually permanent pairs of bolts drilled into the rock. Hangers attached to the bolts allow you to clip carabiners to the anchor. Hangers used specifically for lowering off short sport climbs use spring-loaded gates that enable a climber to clip the rope into them and be lowered without having to untie. The principle requirement of all types of anchors is that they are “bombproof,” that they will not fail under any conceivable load.
MEC encourages the use of modular anchors that can be replaced when worn. These include hangers on expansion bolts and lowering setups such as chains, quick links, and separate carabiners. All components of fixed anchors should meet the CE standard strength requirement of 25kN. Adding bolts and anchors is not a task for novice climbers. You must have proper instruction and training before adding or replacing fixed protection on a climb