The spring-loaded camming device, universally called the cam, is one of the most important inventions in the history of climbing. Before it existed, protecting parallel-sided cracks was difficult, unreliable, and often impossible, which placed a hard ceiling on what climbers could safely attempt. The cam removed that ceiling. It made entire categories of rock protectable, opened the door to the modern era of hard traditional climbing, and transformed destinations like Indian Creek into world-class playgrounds.
This is the story of how the cam came to be, how it works, how it evolved, and why it changed climbing forever.
Before cams: the problem of the parallel crack
For most of climbing history, protection meant placing something into the rock that would hold a fall. The earliest tool was the piton, a metal spike hammered into a crack. Pitons worked but scarred the rock permanently, and the repeated hammering of popular routes caused visible damage that the climbing community came to reject.
The clean climbing movement of the 1960s and 1970s replaced pitons with passive protection: nuts and hexes, metal wedges and eccentric shapes slotted into constrictions in a crack. Passive protection is reliable when the crack narrows, because the metal wedges into the constriction and cannot pull through. But a parallel-sided crack, one with no narrowing, gives a nut nothing to wedge against. On splitter cracks, which run dead straight with parallel walls, passive gear was often useless. Climbers faced long, unprotectable runouts on exactly the kind of rock that is otherwise perfect for climbing.
Ray Jardine and the invention of Friends
The breakthrough came from American climber and engineer Ray Jardine in the 1970s. Working in Yosemite, Jardine designed a device with spring-loaded cams mounted on an axle. When placed in a crack and loaded, the cams rotated outward and pressed against the crack walls, generating outward force that held the device in place even in perfectly parallel cracks.
Jardine kept his invention secret for years, using it to make first ascents of routes that left other climbers baffled at how he had protected them. He called the devices Friends. When the design was finally commercialized through the British company Wild Country in 1978, it changed protection overnight.
How a cam actually works
The genius of the cam is in its geometry. Each cam lobe is shaped as a section of a logarithmic spiral, which gives the lobe a constant camming angle. This means that no matter how far the lobes are retracted or expanded within their range, the angle between the rock and the point of contact stays the same. That constant angle is what converts a downward pull into outward force against the crack walls.
When you weight a properly placed cam, the load tries to rotate the lobes, but rotation only pushes them harder into the rock. The harder you pull, the harder the cam grips. The spring mechanism simply holds the lobes in contact with the rock until the device is loaded. This self-tightening behavior is why a well-placed cam can hold enormous forces in a crack that offers a nut nothing to hold onto.
The evolution of the modern cam
The original Friends used a single axle and rigid stems. Over the following decades the design improved in several important ways.
The double-axle design. Black Diamond introduced the Camalot with two axles, which gave each cam a significantly wider expansion range. A single cam could now protect a broader range of crack widths, reducing the number of pieces a climber had to carry.
Flexible stems. Early rigid-stem cams could be levered out of position or could fail in horizontal placements where the stem was bent over an edge. Flexible cable stems solved this, allowing cams to sit safely in horizontal cracks and pockets.
Micro cams. Specialized small cams extended protection into thin cracks barely wider than a fingertip, opening up routes that had been unprotectable at the thin end of the scale.
Offset cams. Lobes of differing sizes were designed to fit flaring cracks and old piton scars, which are extremely common on classic routes in places like Yosemite.
How cams changed what climbers could attempt
The cam did not just make existing routes safer, it made entire styles of climbing possible. Splitter crack climbing, the discipline of ascending dead-straight parallel cracks, became a protectable and therefore popular pursuit. Areas defined by splitter cracks, above all Indian Creek in Utah, went from curiosities to destinations precisely because cams could protect their relentless parallel lines.
The cam also raised the standard of hard trad climbing. With reliable protection available in more places, climbers could commit to harder moves knowing a fall would be caught. The technical skills of crack climbing and the gear craft of placing cams became central to the trad discipline. For a broader picture of how gear protection fits into the sport, see our guide to traditional climbing.
Placing cams well: the basics
A cam is only as good as its placement. The core principles every trad climber learns: aim for the cam lobes to sit in the middle of their expansion range, not fully open (where it can pull out) and not fully closed (where it is overcammed and impossible to remove). Make sure all four lobes contact solid rock. Orient the stem in the anticipated direction of pull. Avoid placing cams behind loose flakes or in flaring slots where the lobes cannot bite evenly.
Placing gear well is a skill developed over many sessions, ideally with experienced mentorship, and it is the dividing line between gym strength and competent outdoor trad climbing. Even the strongest sport climber must learn gear craft from scratch when moving to trad.
Conclusion
The spring-loaded camming device turned the parallel crack from a death-defying runout into a protectable line, and in doing so reshaped what climbers could safely attempt. From Ray Jardine secret Friends in Yosemite to the double-axle, flexible-stem, offset and micro cams of today, the cam is a story of elegant engineering meeting a real climbing problem. Every modern trad rack is a direct descendant of that original insight: that a logarithmic spiral on a spring could turn a downward pull into an unbreakable grip on the rock.
FAQ
Who invented the camming device?
American climber and engineer Ray Jardine designed the first practical spring-loaded camming device in the 1970s, calling his invention Friends. It was commercialized by the British company Wild Country in 1978 and transformed climbing protection.
How does a climbing cam hold in a crack?
Each cam lobe is shaped as a logarithmic spiral with a constant camming angle. When the device is loaded, the lobes try to rotate, which presses them harder against the crack walls. This converts a downward pull into outward force, so the harder you pull, the harder the cam grips, even in a perfectly parallel crack.
What is the difference between a cam and a nut?
A nut is passive protection, a metal wedge that holds only where a crack narrows and the wedge cannot pull through. A cam is active protection that generates its own outward holding force, so it works in parallel-sided cracks where a nut would be useless. Most trad racks carry both.
Why did cams change climbing so much?
They made parallel cracks protectable for the first time. This opened entire styles of climbing such as splitter crack climbing, turned destinations like Indian Creek into world-class areas, and raised the standard of hard trad climbing by letting climbers commit to difficult moves with reliable protection.
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