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Buying Tips

How to Choose Camming Devices

What are the right cams for you? From cam range, weight, number of axles, stem type, sling type and more, here's the skinny to help you decide.

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A ½-inch cam protects what to most people are finger cracks, while 2- to 2 1/2-inch cams are standard hand-crack size. The ranges listed in the chart are a cam’s maximum expanded and minimum compressed sizes. In the field, however, the ranges will be slightly less, because cams squeezed down to their minimum size will be difficult to impossible to extract, while units placed at their maximum open position will be unstable. Ideally, you place a cam at its mid-range, where it is strongest.

If you, like most people, buy an entire set of cams of the same brand, watch the range overlap from one size unit to the next. Some climbers prefer a lot of overlap, which effectively doubles up your units at their smallest and largest ranges. Other folks like minimal overlap, which gives a given set of cams a broader range, i.e. it takes fewer cams to protect the same range covered by cams with greater unit overlap.


Every ounce you carry on your rack is, for sure, an ounce more to heft up the wall, but weight is only part of the cam-selection equation. More important is a cam’s range. Units with greater ranges are more versatile, so you might actually need to carry fewer of them, lessening the overall weight of your rack. However, at areas such as Indian Creek, you often need multiples of every size, and more cams are merrier, so weight is a true concern.

Black Diamond’s Ultralight Camalots are some of the lightest cams on the market. The weights of each size are: [.4] 61 g (2.15.oz); [.5] 74 g (2.61 oz); [.75] 89 g (3.14 oz);  [#1] 101 g (3.56 oz); [#2] 126 g (4.44 oz); [#3] 167 g (5.89 oz); [#4] 225 g (7.94 oz). Read our full review of the BD Ultralight Camalots.

Number of Cams

Conventional climber wisdom says that four cams are more secure than three, while three-cam units can work in shallow placements where four won’t fit. In reality, both three- and four-cam units are secure in a good placement and some four-cam units have as narrow a profile as three-cam units. Compare brands and choose a camming unit based on how it fits your hand and style of climbing.

Number of Axles

Most cams have single axles and fixed heads, but some, such as certain designs from Black Diamond and Trango, have multiple axles meant to increase the units’ camming range.

Flex Stem

In years past, some cams used a rigid aluminum bar for the stem, but now any cam will have a cable stem that can flex when you weight it in an off-angle or horizontal placement. Repeated falls that bend the stem over an edge will eventually tweak the wire—but that is a small price to pay for security. Most flexible stems are actually “semi-flexible,” with the stem cables sheathed in plastic, which adds durability and stiffness.


U-stem units (each has a cable stem bent into a U shape) are flexible and protect the trigger mechanism and wires, increasing durability, since these are the cam parts that will eventually wear out. The downside is that the stem attaches on the outside of the cams, increasing the units’ head width, which can interfere with certain placements like pods and pin scars. The main disadvantage of this type of stem is that it can be unwieldy for people with big fingers, as the space around the trigger bar can be tight. The U-stem design does allow you to clip a carabiner right to the stem, giving you a few inches of extra reach.

Single Stem

Flexible, single-stem cams work better than U-stem designs in irregular cracks and pockets, and are easier for people with large hands to retract. The exposed triggers and wires, however, are more prone to tangle with other gear and/or shred after repeated falls on horizontal placements.

Sewn Slings

All cams come with sewn slings. Some slings are doubled, letting you lengthen the sling in situations where rope drag is an issue. Just be aware that cam slings are weaker when fully extended. To what extent they weaken is unknown, since cams are tested and rated with the loops doubled. With use, cam slings will eventually fray and need replacing. When this happens, check with the manufacturer for a quality shop that can replace the sling—don’t do this yourself on your mom’s home machine!


Color-coded units will let you quickly identify sizes and pluck the right unit off your rack. Unfortunately, most manufacturers use different color-coding systems. Confusion reigns when you mix cam brands.

Passive Strength

You would not choose to depend on a cam that’s slotted nut-style in a passive mode (cams fully out), but units with a rated passive strength give you an extra margin of safety in those rare times when you place the cam in a hole or pocket and the cams spring full out, or, out of nuts, you are forced to slot a cam into a crack in passive mode.