Hand Cracks: Getting a Hand Jam to Hold Your Body Weight, Thumbs Up or Down, Thin Hands and Cups

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A hand-width crack is the size most people learn first, and the most secure. When the jam is good, you can hang off one hand to rest and even let go with your fingers without falling out. Finger cracks, fists and offwidths all grow out of this move.

This is post 1 of the Crack Climbing Technique series. The shared rules of jamming are in the crack-climbing primer; this post is only about hands. It covers five things: how to get a jam to hold your body weight, which way the thumb goes, what to do when the crack is a bit tight or a bit loose, how to move your hands, and what your hand size changes. Feet are the next post.

By the end you should be able to place a hand jam on a gym crack or a hand crack at Long Dong that holds your weight without your fingers doing the work.

A good hand jam in four steps

The steps are nearly identical across sources. This version follows British crack climber Pete Whittaker (Wide Boyz) in his newsletter:

1. Relax and flatten the hand before it goes in. Spread thumb and fingers into an L; the thinner the better. He says a lot of people make the jam shape before the hand is even in the crack, and then it can't go deep.
2. Slide it in to around the wrist.
3. Tuck the thumb into the palm and push it toward the little finger. The muscle at the base of the thumb bulges and widens the hand. That's where a hand jam's strength comes from.
4. Press straight fingertips against the opposite wall. It's extra support; the strength still comes from the thumb.

In another newsletter Whittaker says finger pressure should be minimal, there for the extra 20–30%. In a perfect jam you can hang easily without pressing your fingers against the opposite wall. Pumped fingers usually mean too much finger pressure and too little thumb.

Where you jam matters too. Climbing.com's Julie Ellison adds in How to Hand Jam: look for a constriction below, where the hand wedges like a nut, so you use less muscle and more skeleton.

Kim Jong-sik, a Korean climbing guide and a founding figure of the Korean climbing-guide association KMGA, boils the same move down to a four-beat mnemonic, "L-in-thumb-tip", at the start of his 12 jamming techniques lesson:

• L: stand the thumb up in an L.
• In: slide the knife-edge of the hand into the crack.
• Thumb: bend the thumb so the muscle at the heel of the palm hardens.
• Tip: lock it with fingertips against the rock.

The video has embedding disabled, so watch it on YouTube.

Japanese climber Chikugon's 2026 beginner video shows the same thing on a practice rig at the start. Spread the hand until thumb and index finger are close to a right angle, which makes the hand thinner so it goes deeper; push in to the base of the thumb, then draw thumb and index finger inward. From 2:30 he adds a tip: keep your elbow tucked to your side and pull the hand gently toward you. When the skin on the back of your hand goes tight, the jam is set.

Something you can do tonight: leave a hand-width gap between two thick books on a shelf and practise three beats: relax and flatten as you slide in, tuck the thumb toward the little finger, expand. Then lift your fingers off the book and see whether the jam still holds.

The four most common mistakes

YouTuber Geek Climber had only ever climbed in a gym, and this video records Pete Whittaker coaching him remotely for 35 days to learn cracks. Pete points out three of the four mistakes below in the video.

Not going deep enough. The crack edge sits across the base of your fingers and only half the hand is in. At 0:40 Pete says beginners fail on the very first thing, getting the hand in deep enough; the edge should sit in front of the wrist, not across the base of the fingers. From 1:16 his mnemonic for the steps is "L, in, thumb, fingers", almost identical to Kim's four beats above.

Grabbing the edge with your fingers. A habit from the gym. US instruction channel VIDEORACLES says at 1:05 in its hand-jam lesson that many learners try to grip the edges of the crack with their fingers, and that isn't an efficient jam.

Jamming at chest height. At 2:10 Pete explains that when the jam is too close to your chest, your elbow flares out and you lean back. Place the jam higher, so your chest stays close to the wall and your weight stays on your feet. From 5:19 he adds that your arm should stay in line with the crack, so your wrist doesn't twist.

Pushing too hard with your fingers. Constant finger pressure pumps you out and hyperextends joints. Go back and check that the thumb is tucked tight.

From 5:00 he also says his feet hurt twice as much as his hands, and Pete tells him to drop his heel; the next post on foot jams picks that up.

Something you can do tonight: on a gym crack or your book gap, ask a friend to watch three things: whether the crack edge is at your wrist; whether your fingers are grabbing the edge; whether the jam is too low, making your elbow flare.

Thumbs up or thumbs down?

This is the most common question on hand cracks. Sources agree that it depends on the situation:

For placing gear or shaking out, thumbs-down works well; for efficient upward progress, or an extra-long reach off a hand jam, it's almost always thumbs-up (Ellison; Tom Randall in UKC's crack school).

VIDEORACLES demonstrates a perfect hand jam from 0:50 and compares the two from 1:41. Thumbs-up, the angle of his elbow lets him pull all the way up. Thumbs-down, he can hang and rest, but as soon as he moves, it wrenches his elbow into an awkward angle. So he often places a thumbs-up jam right below a thumbs-down one.

Not everyone agrees that thumbs-down is more secure. In one Mountain Project thread, the original poster says he avoids it whenever possible because it's anatomically harder and limits how far each move goes, except in corners. He and another poster both say they used it a lot while learning and now default to thumbs-up.

Beginners reach for thumbs-down naturally. Japanese channel Noboru Kyojin, new to cracks, filmed himself on the first pitch of Sayonara Momoe-chan (5.9) at Ogawayama. At 3:15 he says he kept jamming thumbs-down without meaning to, and wasn't sure which way was correct.

Something you can do tonight: on your gym's crack wall, top-rope two laps: the first all thumbs-up, the second all thumbs-down. Compare which lap gave you longer reaches and which made it easier to stop and rest. No crack wall? Hang ten seconds each way in your book gap and compare your elbow angle.

Too tight, too loose: thin hands and cups

A perfect hand jam fits only one width. A little narrower or a little wider and you have to adjust.

Too tight (thin hands): the thumb won't tuck into the palm. Crimp the index and middle fingers to make room for the thumb to go deeper, then push against the crack wall with the outside of the thumb (Whittaker). This size never feels very secure: twist thumbs-down, place your feet with extra care, and let go of the idea that the jam should feel as solid as a standard one (Jeff Achey, Jam Session).

Too loose (cups): the expanded hand still doesn't fill the crack. Cup the hand, pressing fingertips and the heel of the palm on one side and the backs of the knuckles on the other. The knuckles are a single sharp point of contact, so this size hurts; tape them first (Achey). Then twist: with the hand cupped and fingers straight, tips pointing into the crack, rotate toward your little finger, clockwise for the right hand and counterclockwise for the left, thumb up or thumb down (Tony Jewell's wide-hands lesson).

Cups have their critics too. In a Mountain Project thread on rattly hand cracks, some prefer a thumbs-up jam with the thumb rolled sideways over cupping, because cups press on the bones on the back of the hand and leave bruises.

Climbing YouTuber Anna Hazelnutt took a lesson in Tom Randall's cellar crack. Thin hands (paddle) start at 14:14 and cupped hands at 17:23, so you can watch how Tom adjusts the hand shape. The VIDEORACLES lesson above covers thin hands at 2:49 and cups at 3:36, for comparison.

Something you can do tonight: narrow the gap between your books a little and try thin hands; widen it and try cups and cup-and-twist. Note the width where you have to change hand shape.

Moving your hands: cross or shuffle

Straight cracks usually go hand over hand, both thumbs up: fast rhythm, long moves.

Leaning cracks and corners call for shuffling: the top hand thumbs-down, the bottom hand thumbs-up, never crossing, each inching up in turn. In UKC's crack school, Tom Randall says that when the crack is in a corner or the edges overlap, crossing hand over hand is almost impossible. Jewell adds a rule for direction: if the crack veers left, lead with your left hand, and vice versa. The laybacks, corners and leaning cracks post goes into this in detail.

American pro climber Sasha DiGiulian comes from sport climbing. In a video posted in early 2020, she learns cracks at Indian Creek from the people she's climbing with. From 1:51 she explains: in a corner, her lower hand jams thumb-up and her higher hand thumb-down; in a straight-in crack she just goes hand over hand, like swimming up.

UK instruction channel JB Mountain Skills leads an E4 leaning crack from 2:51 in a 2023 video, which shows shuffling on real rock.

Kim Jong-sik also has an episode on Insubong's leaning cracks, splitting them into two types with a plan for each (embedding disabled). In Taiwan, Twilight Crack (5.11b) at Long Dong's First Cave turns a roof band, then follows a leaning crack above; see rock6879's ascent.

Straight cracks aren't always hand over hand, either. Many on Mountain Project find both thumbs up least tiring on long, straight, wide-hands splitters at Indian Creek, but switch to shuffling when the crack is deep or they're placing gear.

Something you can do tonight: find a leaning crack or a corner at your gym and climb it by shuffling, never crossing. Afterwards, ask yourself: which hand stayed on top? No leaning crack? Practise inching both hands up your book gap, top hand thumbs-down and bottom hand thumbs-up.

Big hands and small hands

The series overview explained that the same crack is a different size for different hands. For hand-crack sizes, Whittaker's comparison looks like this:

• 0.75 and 1: perfect hand jams for small hands; big hands have to use the thin hands from the previous section, flattening and forcing the hand in.
• 2: a basic, solid hand jam for big hands; small hands often need the cups from the previous section.

So "this is a hand crack" often means "this is a hand crack for big hands". Ellison, author of the Indian Creek commandments, also mentions that she assumed her small hands were between a .75 and a #1, until a lap on Incredible Handcrack showed they were between a #1 and a #2.

In Wide Boyz' 2020 video Feet first VS hands first, Mari Salvesen, whose hands and feet are both small, can't fist jam where Pete can and switches to a teacup jam, using her thumb as a spacer. Small hands aren't a flaw; they need a different set of techniques, which the fist and offwidth posts cover.

Something you can do tonight: at your gym's crack wall or on a friend's cams, find which size gives you your most comfortable hand jam and save it in your phone. Next time a topo says "#2 hands", convert it to your hand number first.

On real rock: from first routes to classics

Watching people jam on real rock shows the gap between lessons and the crag. These come from different crags and different levels:

• Indian Creek (Utah, USA): a 5.7-level recreational climber's learning record trying Flatline (5.10). He doesn't send, and you can see every struggle.
• Squamish (Canada): Klahanie Crack (5.7) is a dead-straight granite hand crack; this ascent is a good preview of a first outdoor hand crack.
• Ogawayama (Nagano, Japan): besides Sayonara Momoe-chan above, Chikugon also filmed the beginner classic Casablanca (5.10a) in this ascent.
• Insubong (near Seoul, South Korea): Chouinard A is a route Patagonia founder Yvon Chouinard put up in the 1960s while serving in Korea (Mountain Project). Korean climber Somaek Climber filmed a climb of it through pitch 4 in strong wind.

Long Dong in Taiwan has hand cracks too. The Long Dong section of the primer introduces Noodle Line (5.8) at the First Cave: fist and hand jams in a corner, on sharp rock that calls for tape or long sleeves.

Something you can do tonight: pick one of the videos above, mute it, and watch three minutes of hands only: which way the thumb points, how high the jam is, when they cross and when they shuffle.

Practice questions: six scenarios

Answers are under each question. Think first, then open.

1. You're hanging on a hand jam and your fingers pump out quickly.

2. You're on a straight hand crack, thumbs down the whole way, and every move feels short.

3. The crack is a little narrower than your hand, and your thumb won't tuck into your palm.

4. The crack is a little wider than your hand, and the jam still rattles when you expand.

5. The crack leans up and right. You're crossing your hands and keep feeling like you'll swing off.

6. A friend says a 5.10 hand crack at Indian Creek is perfect for beginners. Your hand number is 0.75.

Next

Now that your hands can jam, it's your feet's turn. Most of the work in crack climbing is in the feet, and the next post covers how to place them, how deep, and how to keep them from hurting or getting stuck. If you don't have a crack wall nearby, the series' crack-training post covers building your own practice crack. The series overview shows where the other sizes fit. To lead hand cracks at Long Dong you also need to place protection; see the trad protection guide.

References

• The crack size map | Crack Climbing Technique
• The crack-climbing primer
• 3 Techniques Crucial For Crack Success (Pete Whittaker, Wide Boyz newsletter)
• The one way to truly rest on a hand jam (Pete Whittaker, Wide Boyz newsletter)
• A New FA in Kristiansund and the Golden Takeaway (Pete Whittaker, Wide Boyz newsletter, 2026)
• How to Hand Jam (Julie Ellison, Climbing.com)
• Wild Country Crack School Part 2 – Jamming (Tom Randall, UKC)
• Jam Session (Jeff Achey, Climbing.com)
• How to Climb Wide-hand Cracks (Tony Jewell, Climbing.com)
• The 10 Commandments of Indian Creek (Julie Ellison, Climbing.com)
• Thumb up thin hand technique (Mountain Project forum)
• jams for rattly hands? (Mountain Project forum)
• Sustained straight up wide hands (Mountain Project forum)
• 12 jamming techniques: how to get good at crack climbing, part 2 (K Climbing Company, Kim Jong-sik, 2023, in Korean)
• Leaning cracks on Insubong and elsewhere (K Climbing Company, Kim Jong-sik, 2021, in Korean)
• Crack climbing for beginners: hand jam basics (Chikugon, 2026, in Japanese)
• Pro Climber Coaches Gym Climber to Learn Crack Climbing in 35 Days (Geek Climber, 2022)
• Crack Climbing: Jamming Hands and Fists (VIDEORACLES, 2020)
• Intro to hand jams: Sayonara Momoe-chan, pitch 1 (Noboru Kyojin, 2023, in Japanese)
• secrets from the crack cellar: HOW TO CRACK CLIMB, 5 techniques with Tom Randall (Anna Hazelnutt, 2021)
• Sasha DiGiulian crack climbing tutorial in Indian Creek (Sasha DiGiulian, 2020)
• Training for Climbing is POINTLESS. Leaning Crack E4 6a (JB Mountain Skills, 2023)
• Long Dong Twilight Crack (rock6879, 2024, in Chinese)
• Feet first VS hands first (Wide Boyz, 2020)
• Learning How To Crack Climb (Flatline 5.10) - Indian Creek (John Minar Photography, 2023)
• Squamish Rock Climbing | Klahanie Crack 5.7 (Alpine Gremlin, 2022)
• Ogawayama Casablanca 5.10a (Chikugon, 2023, in Japanese)
• Insu-bong (Mountain Project)
• Insubong Chouinard A, pitch 4 (Somaek Climber, 2024, in Korean)
• Ogawayama | Japan Climbing Crags
• Insubong | Korea Climbing Crags
• Trad protection: nuts, cams and the three conditions of a good placement

Update Log

• 2026-10-27: Foot jams is published; "the next post" now links to it.