2012 Gear Guide: How to Buy - Cams
If you’re getting into traditional climbing, or upgrading your rack, a set of spring-loaded camming devices will be your biggest expense: At $50 to $90 each, you’re looking at $500, minimum, for a modest selection of units. The good news is that modern cams offer excellent value: They work beautifully and will last much longer than your shoes, ropes, or harnesses.
Cams work by converting the force of a fall (or your body weight) into outward pressure on the sides of a crack, wedging the piece in place. You pull a trigger to retract the cams, insert the unit in a placement, and then release; a spring holds the cam lobes in contact with the rock, ready to rotate and grip under load. Pretty simple. But putting this principle into action in a strong, lightweight, ergonomic unit has occupied climbing-gear designers since the 1970s, when cams first appeared on the commercial market. The diversity of units now available is impressive—and daunting for the first-time buyer.
Start with half a dozen cams of the same model from a single company, in sizes from 0.5 inches to 3.5 inches. You’ll find it much easier to memorize each unit’s size range—a key to quick placements—if you outfit your first rack with the same model. See what cams local climbers use—some styles may be more popular because they work better in the local rock. Soft rock, tiny placements, lots of wide or horizontal cracks, and wandering pitches all may make certain cams more suitable than others for your home crags.
Anatomy of a Cam
1. Lobes: Most spring-loaded camming devices (SLCDs) have three or four lobes (aka cams) that rotate around axles. When a climber weights the device (as in a fall), the downward force is transferred to the lobes, which press outward against the rock, holding the device in place.
2. Cam Angle: The lobes’ curve is based on a logarithmic spiral, so the lobes contact a vertical wall at the same angle throughout the effective range of the device. This constant cam angle ranges from about 12.5° to 14°. All other things being equal, the tighter the angle, the more outward force is generated, but the smaller range of placements a device will have.
3. Springs: Each lobe is held open in its widest position by an individual spring, so the device will stay in place inside a crack when it is not weighted.
4. Axle: Most cams rotate around a single axle, but two SLCD designs now employ double axles, which allow a much greater range of placements.
5. Stem: Loads are transferred to the axles and thus to the lobes through a stem, usually made of steel wire. Flexible stems bend when they are loaded over an edge, such as in a horizontal crack.
6. Clip-in Point: All SLCDs have sewn slings attached; some can be extended to reduce rope drag and help prevent cams from “walking” out of their ideal placements. Many devices have a loop in the stem where you can clip in for extra reach while aid climbing.
To help choose your camming units, consider the following specifics.
A unit’s trigger action should be firm, silky, and consistent throughout the range, and the cams should snap smartly back when you release the trigger. Look at the finishing: Are all edges rounded, trigger-wire ends peened and/or recessed, non-metal parts durablelooking and well-fitted? Are there any sharp parts exposed anywhere on the unit? Compare different manufacturers’ offerings side by side—in a shop, with your own eyes and hands, and not online—to form a baseline impression.
Number of Cams
Larger units will have four cams, but in the fingers-and-under sizes, you’ll find some units with three lobes. TCUs (three-cam units) are less prone to “walking” out of their original position as they wiggle in response to the moving rope. They also may be narrower along the cam axle, so they fit in tighter placements. Plus, the one-in-themiddle, two-on-the-sides lobe set-up works better for certain tricky pocket placements. All that said, small four-cam units have their own advantages. They typically spread the load better—good for softer rock—and some of them are nearly as narrow as TCUs.
The stem connects the cam axle to the clip-in loop or sling. The original camming units had rigid aluminum-bar stems, but flexible-cable stems now rule. These may be either a single cable centered on the axle, or a U-shaped loop of cable attached to each end of the axle. You’ll often find non-metal parts attached to the stem to protect it and/or the trigger wires from abuse.
Single-cable and twin, U-cable designs each have advantages, but instead of reflexively picking one over the other, evaluate how the whole system works. Are delicate trigger wires—any camming unit’s most easily damaged parts—shielded and protected, or are they exposed to abrasion and prone to tangle with other units on your rack? Will the unit flex too much when you try to remove a stuck piece? If you plan to use the cam for aid climbing, will it handle a horizontal placement without seriously deforming the cables? Does the trigger work well with the stem to provide a secure grip? Could you use the unit while wearing gloves?
For units up to finger-crack size, don’t worry about weight. But for big pieces, or for big racks of mid-sized pieces, weight adds up. A difference of one ounce per cam can easily add a pound to a large rack. Also, consider overall size. Short-stemmed units save weight and make for a tidy rack, but you’ll sacrifice reach on overhead placements. They're also more likely to walk out of reach and get stuck.
Especially for aid climbing, you’ll want the option of clipping the unit in two places: directly at the end of the stem or to its presewn sling. In addition, some brands have doubled clip-in slings that you can extend to reduce rope drag—an excellent feature that may halve the number of quickdraws you need to use on a pitch.
The wider the range of effective placements you can get out of each unit, the more versatile it is. Black Diamond Camalots, with their double-axle design, used to edge out all competitors for expansion range. Not anymore. The patent has expired, and though Camalots are better than ever, they have competition from many new designs: single-axle, double-axle, and unique solutions like the Omega Pacific Link Cam, in which the cam lobes separate to create a huge placement range for each unit.
Most, but not all, modern camming units can be placed “passively,” like nuts, a feature that is often useful if a cam wiggles out of its intended placement and wedges umbrella-style inside a crack or flake. Such placements typically aren’t pretty, since the unit may rattle around, but it can be strong—as long as the unit features beefy cam stops. These milled tabs or slots prevent lobes from moving beyond their fully expanded positions.
For most trad-climbing areas, the first “specialty” pieces you should consider when upgrading your rack are “offset” or “hybrid” cams—four-cam units with one pair of cams larger than the other. Originally designed for aid climbing in flared piton scars, these units are quite versatile for regular trad climbing as well; they can turn sketchy flared cracks or pods into plug-and-chug terrain.
For soft-rock climbing, consider units with increased surface area and more aggressive teeth on the cam lobes—like the Metolius Fat Cam.
For very small or very large cracks, many climbers shift from their favorite brand to specialty designs. Unconventional options such as Big Bros (spring-loaded, expandable tube chocks that fit in cracks up to squeeze-chimney width) and Ballnuts (a sliding-ball-wedge thingie for the thinnest of thin cracks) are both excellent, time-tested designs that eventually make it into most serious trad climbers’ gear arsenals.
CLEAN THEM. When cams get wet, towel- and air-dry them before putting them away. UV light damages the slings, so store cams out of direct sunlight. To clean a cam, first swish the head in nearboiling water, activating the trigger to move the lobes. Squeeze a few drops of dishwashing liquid onto the moving parts and scrub with a toothbrush. Use a Q-tip for hard-to-reach spots on smaller cams. Swish-and-trigger in the hot water again, making sure all the soap is rinsed off. Blow-dry with compressed air, if possible, or towel- and air-dry.
LUBE THEM. After cleaning your cams, always lube them, but do it sparingly. Your best bet is a wax-based lubricant such as Metolius Cam Lube or White Lightning bike-chain lube, both which repel dust and grit better than WD-40, though this also works fine. (All are likely harmless to slings, but if you do a neat job, you should be able to keep it off them.) Apply a drop or two to each joint and activate the trigger. Wipe off all excess lube. Some climbers prefer a dry, graphite-based lube, available at most hardware or auto-parts stores, which works well. Always rinse and re-lube cams (and any other metal climbing gear) after climbing near saltwater.
FIX THEM. Cams can last 20 years or more if properly cared for, but after a few years of hard use you’ll probably need to replace some trigger wires and the slings. Some manufacturers offer replacement trigger kits, and some will replace slings or trigger wires for a reasonable fee. Mountain Tools (mtntools.com) also reslings cams and nuts. Inspect cams frequently and immediately straighten any bent trigger wires, or the cam lobes won’t retract evenly. Once a wire starts to fray, have it replaced. Murphy’s Law definitely applies to cams: A frayed trigger wire will break just as you try to place the cam during a desperate runout.
Replace the sling if:
- It’s more than 10 years old.
- It’s noticeably faded.
- It shows visible abrasion or any damage to the stitches.
Retire a unit if:
- It has held a truly severe fall.
- A cam lobe is deformed in any way— flattened, bent, or out of alignment. The cam angle will be affected and the unit will not grip properly.
- Any of the stem-cable wires are frayed.
- The cam axle is bent or the cams wobble on the axle.
Keep cam slings—and all nylon gear such as ropes or quickdraws—away from batteries in your garage or car trunk. Even battery fumes can destroy nylon.