Here's a thing most climbers never question: the flat 20mm edge. It's the standard, the reference, the thing everyone tests on. And for measuring strength, standardization is exactly what you want. But for training, a flat edge makes an assumption that's just anatomically wrong. It assumes your four fingers are the same length.
They aren't. Look at your hand flat on a table. The middle finger sticks out furthest, index and ring sit back a bit, and the pinky is shortest by a fair margin. On a flat edge, that staggered geometry means the fingers don't all contact and load the same way.
What actually happens on a flat edge
When you crimp a flat edge, your longer fingers, mostly the middle, contact the lip first and take a disproportionate share of the load. The shorter fingers, especially the pinky, contribute less because they're not engaging the edge at the same depth or angle. You end up with uneven loading across the four fingers even though it feels like a unified grip.
To get all four on evenly, you have to adjust: bend the longer fingers more, or roll the wrist, or accept that the middle finger is carrying the team. Your hand adducts and repositions to compensate. That compensation is fine on the wall, where holds are irregular anyway. On a training tool meant to build balanced finger strength, it means some fingers get trained harder than others.
Why uneven loading matters for training
If the goal is balanced finger strength, and for injury resilience it often should be, you don't want your middle finger doing most of the work every session while the pinky coasts. Underloaded fingers don't adapt as well, and finger-strength imbalances are common in climbers. The point of a dedicated training edge is to load what you want to load, deliberately. A flat edge partly undermines that by defaulting to the longer fingers.
There's also a joint-strain angle. When fingers load unevenly, the ones bearing more take proportionally higher stress, which over time is a plausible contributor to the finger-by-finger injury patterns climbers know well. Even loading spreads the demand.
What an unlevel edge does
An unlevel or podium edge is cut so the contact surface steps or curves to match the natural stagger of the fingers. The longer fingers sit slightly lower, the shorter ones slightly higher, so all four contact and load closer to equally in a natural open-hand position. It's a small geometric change that addresses the length mismatch directly.
| Flat edge | Unlevel edge | |
|---|---|---|
| Finger loading | Biased toward longer fingers | More even across all four |
| Best for | Standardized testing, general strength | Balanced loading, comfort, reducing over-bias |
| Grip encouraged | Whatever compensates for the stagger | Natural aligned open hand |
| Skin drag | Uniform | Often reduced by the profile |
Test on flat. Train on unlevel if balanced loading and comfort matter.
The honest caveat
A flat 20mm edge is still the right tool for one thing: testing. Because it's the universal standard, it's how you compare your numbers to yourself over time and to other climbers. Don't throw it out. Test on flat, and consider training on unlevel if balanced loading and comfort matter to you.
Also, the difference isn't dramatic for everyone. Climbers with more even finger lengths, or who naturally grip in a well-aligned position, get less out of an unlevel design. It's most useful if you know you're middle-finger-dominant or you want to protect against the imbalance developing. As with most gear, it solves a specific problem rather than being a universal upgrade.
If the fit argument lands for you, the Unlevel Edge is built around exactly this: a profile that supports the DIP joint and encourages even engagement across all four fingers. Read the full product story in What is an unlevel edge and why use one? For depth and progression choices, see our complete guide to choosing the right training edge.