All About Nuts, Chocks, Wired Nuts, and Micro Nuts

Nuts are Essential Climbing Equipment

climbing nut
Climbing nut in use. (Iwona Erskine-Kellie/Wikimedia Commons/CC BY 2.0)

Nuts are simple climbing tools used to protect traditional climbers as they lead up cliffs. Nuts are pieces of metal of various sizes and shapes that are slotted, jammed, and wedged into constrictions in cracks by a lead climber. A length of thin cord or sturdy wire cable, permanently attached to the nut, allows a climber to clip a carabiner or quickdraw into the nut, securing him and his rope to the cliff face as he climbs or at a belay anchor. A properly placed nut is bombproof—it won’t readily come out of a crack and if it’s weighted, like in a fall, it only wedges tighter into the crack.

Nuts are Passive Protection

Nuts are called “passive protection” because they have no moving parts and work passively, wedged inside a crack and waiting to hold a fall. “Active protection” like cams, on the other hand, uses a camming principle of opposing forces to hold inside a crack. A cam, which is a curved piece of metal, actively expands out in a crack and is forced against the crack sidewalls to hold it in place and to catch a fall. If you pull on a cam, it actively resists being pulled out.

Nuts Have Lots of Names

Most climbers now call these metal wedges simply nuts, which encompasses the wide variety of differently-shaped nuts. Nuts are also called artificial chockstones, usually shortened to just chocks, or by the nut brand names from Yvon Chouinard’s Great Pacific Ironworks (which later became Black Diamond) in the early 1970s, including Stoppers and Hexentrics or Hexes. Nuts are sometimes referred to by their shapes, such as wedges or tapers. Smaller-sized nuts with a stiff wired cable are usually called wired nuts or wires, while the tiniest nuts are logically called micro nuts or simply micros. Sometimes micros are generically referred to as RPs, the first brass nuts made.

Nuts Evolved in Britain

Nuts evolved in the 1960s as a clean climbing alternative, especially in Great Britain, to pitons, which, when hammered into cracks and then removed, leave gaping scars and damage the rock surface. Both the name and climbing use of nuts originated in Britain when climbers took large metal machine nuts, filed out the threads inside the nut, and then tied a piece of cord through the nut. Presto! There was a piece of gear that could be wedged into a crack as a sturdy anchor.

Backbone of a Trad Climber’s Rack

Nuts, however, are the backbone of a trad climber’s rack and do lots of hard work keeping an experienced climber safe. Many leaders will always choose a well-placed nut over a cam any day since cams can do funny things, like walk out of a crack. A solid nut placement is basically foolproof and usually doesn’t move or shift if it’s well-seated, giving important peace of mind on tricky climbing sections.

Nuts Have Lots of Sizes and Shapes

Since climbers first began using machine nuts, the design of nuts has evolved from those simple hexagonally-shaped nuts to complicated, lightweight, and strong pieces of climbing gear that are specially designed climbing tools. Modern nuts not only wedge into cracks but also have curved faces and tapers to fit a wide variety of irregularly-sized cracks.

Standard Nuts Come in Lots of Shapes and Sizes

Most modern nuts are designed to orient either lengthwise or widthwise in a crack, while others have differing angles so they’re offset and fit snugly in flaring and shallow cracks and piton scars. Nuts also come in a huge variety of sizes with a set of regular nuts ranging in size from about 0.1-inch thick to 1.45-inches thick, depending on the manufacturer. Standard nuts are made from aluminum so they’re light and durable and come with a full-strength cable, which is looped through the nut and connected with a swage, for clipping a carabiner.

Micro Nuts are Specialized Tools

Micro nuts are specialized nuts for thin cracks and seams. These nuts are not necessarily tiny little things, because the larger micros are bigger than the smallest standard nuts. Instead, micro nuts are made from a variety of metals, including aluminum, bronze, iron, and copper. Most micro nuts are made from bronze, a soft metal alloy, which allows the nut to grip a crack better and more tightly than a regular aluminum nut. These micro nuts, however, are somewhat delicate since they can deform and shear out under a load, especially when placed in hard rock. The smallest micro nuts are used only for aid climbing since they basically hold body-weight rather than a fall load, plus the cable is very thin and can break when shock-loaded.