Learn to hold slopers: open hand, as much skin as possible, body under the hold. Slip less, with a progression, common mistakes and an honest look at chalk.
You do not hold a sloper with your fingertips but with your whole hand: open, flat, with as much skin as possible on the surface and your body positioned so that your pull points into the hold instead of away from it. The honest answer to "Why do I slip off?": usually not too little strength, but the wrong angle and too little skin contact.
The open grip has one advantage: in a biomechanical model the full crimp loaded the A2 pulley 36 times more than the open slope grip, and the A4 four times more [1]. For beginners the sloper is therefore pulley-friendly. The downside: in cadaver fingers, at the same tendon load of 40 newtons (about 4 kilograms), the crimp always produced more holding force at the hold than the slope grip [2]. On a sloper you lack the lever of the fingers, and you replace it with friction and position.
Friction can be learned. In a study of 22 climbers, experienced climbers applied more friction to an instrumented hold. The ratio of pull to pressing force ranged from 0.53 (Teflon) to 0.84 (rubber) depending on the surface, roughly 5 to 8 kilograms of sideways pull per 10 kilograms of pressure, and climbers judged surfaces by their "grippiness", not their roughness [3].
This guide is about the single sloper. Pressing two slopers against each other (compression) is its own pro skill.
Honest classification: this is an intermediate skill. The feel for the angle builds over weeks (experience value, not proven), and on bad days you look weaker than on edges.
Entry criteria (practice standard):
On the hold, look for the spot where the surface faces you the most. The surface is the force, not the edge. Brush the hold before you touch it.
Milestone: on every sloper you know where your best contact zone is.
Spread the fingers loosely, lay palm and finger pads on the surface and do not dig the fingertips in. The wrist hangs under the hand, the shoulder stays low. Your pull should run as close to perpendicular into the surface as possible.
Milestone: you hang ten seconds on a medium sloper with your feet on the ground, lightly unloaded, without the hand creeping.
The further your weight hangs away from the hold, the more the pull tips outward and the hand slips. Bring hips and centre of mass close to the wall and under the sloper. This fits the "optimal wall contact" principle from sports science [4].
Milestone: you hold the sloper for 15 seconds with feet on holds, hips close.
Place the feet so they carry your weight. Push through the toes and keep the trunk tight. Any sagging of the hips turns the pull outward.
Milestone: you move a foot without the sloper hand wandering.
Lay the hand on, let it "stick" for a second and only then give weight, slowly and evenly. Move without jerking, also when re-gripping.
Milestone: you climb three slopers in a row without re-gripping.
A sloper can let go without warning: friction breaks, the hand slips, you fall. An edge often leaves you a moment to react, a sloper does not. So keep the fall zone clear and land feet first with soft knees. In a prospective study of 507 boulderers, lower-limb injuries made up only 23 percent of all injuries but were more often severe and more often caused by falls and jumping off [5]. Scrapes on hand and forearm are typical too.
For the fingers the sloper is comparatively gentle [1], for shoulder and elbow it is not automatically so, because you hang for a long time on straight arms with lots of trunk tension. Stop if you feel pain. This does not replace supervised training.
Chalk on slopers: the evidence is contradictory. In a study of 15 people chalk reduced the friction coefficient on rock [6], in another with nine climbers chalk increased repetitions in open-handed pull-ups [7]. Both measure something other than a real sloper. Pragmatically: brush the hold, chalk sparingly, wipe your hands.
Do a friction test before you give weight: swipe your hand firmly across the sloper once (as across a tabletop). If it slips immediately, no show of strength will help. Then brush, rest or change the contact zone. This is practical experience, not proven, but a two-second test saves you ten failed attempts. Friction is not forced, it is prepared.
A sloper is a round, edge-free hold that you do not grip with the fingertips but hold through friction and hand contact. Depending on its shape you need an open, flat grip and a body position in which the pull points into the surface.
The open slope grip. In a biomechanical model the load on the A2 pulley was 36 times lower in the slope grip than in the full crimp, and four times lower on the A4 [1]. In return you lack the finger lever, so you need friction and clean position.
Scientifically that is open. One study found less friction with chalk on rock [6], another found more repetitions in open-handed pull-ups [7]. Practically: brush the hold, chalk sparingly, wipe your hands and use the friction test to see whether it works for you.
Holding a sloper means a single sloping hold that you keep with an open hand and good position through friction. Compression means pressing two holds or a volume against each other. That is its own shoulder-heavy pro skill that builds on the sloper feel.
Matching: Both Hands on One Hold