Cam hooks, originally designed by Ed Leeper, are simple, hard-steel levers that wedge in thin cracks, dihedrals, under roofs, and even in pockets or boxy pin scars. Moses Enterprises makes them now in several sizes ($10.95 each, mosesclimbing.com). Cam hooks are most at home in cracks too thin for camming units, where you’d otherwise aid by nutting or pounding Lost Arrow pitons. Nuts that you’ve weighted, especially small brass ones, can be difficult to remove and often become trashed in the process. Cam hooks, in contrast, pop out easily. The downside is that a placement that’s secure while you’re standing on it may fall out when unweighted, making cam-hooking a little spooky.
A textbook placement will utilize a slot-like widening in the crack—typically a subtle pin scar—but unlike nuts, cam hooks do not need a constriction in the crack to work. Bury the blade anywhere it will fit, clip an aider to the cam hook’s sling, and stand up—the hook holds firm by putting wicked leverage on the sides of the crack. For this reason, consider all other options before cam-hooking on soft sandstone (such as found in Zion National Park), since the hook can blow out the edges of the crack just like a piton would. A reduced-leverage, “fragile flake” version of the hook is available for softer rock.
Avoid bounce-testing when moving between cam hooks, since this will unweight your lower placement, possibly causing it to fall out. Instead, slot your new placement carefully, set and test it with a firm step in your aider, then move on up.
Flared cracks make cam-hooking tricky and less secure, and in slightly acute corners you’ll need a wider crack in order to insert the hook’s slightly curved blade—the smallest size hook may come in handy here. Very acute corners can’t be cam-hooked. Aid horizontal cracks by placing the hook upside down.
Tests by Chris McNamara of supertopo.com found that cam hooks’ rectangular-stock blades seemed to hold a bit better when worn and rounded than when brand new, so you might try gently hand-filing the corners of new hooks to get a bit more surface area and bite. Never use a grinder; the heat can ruin the steel’s temper and springiness.
By clipping a cam hook to each aider, you can efficiently leapfrog or shuffle your way up a crack. When the run-out starts to feel too spicy, leave a nut or cam as protection. (A nut placed only for protection will be much easier for your second to remove than one you’ve stood on.) It’s sometimes possible to leave a particularly well-wedged cam hook in place for protection, but back it up as soon as possible! If you’re cam-hooking horizontally, under a flake or roof, give some consideration to how your second will follow and adjust your tactics accordingly.