Feet Slipping in Climbing Shoes...is it Sizing or Sweat?

In a recent YouTube video, climbing gold medalist Erin McNiece was telling V17 climber Will Bosi why she chalks up her feet. 

“My feet get really sweaty” she said. “And sometimes I can feel movement inside of my climbing shoes.”

So she chalks her feet to try and keep them dry. 

That movement can be a huge problem. Regardless of if you are a beginner or a pro climber like Erin.

So no...you’re not imagining it!

Your foot rolls half a centimeter inside your climbing shoe shoe on a tiny foothold. You notice your toe slide. Weight that should be locked on an edge suddenly isn't. It usually starts mid-session, gets worse as the session goes on, and it's one of the most common issues climbers talk about online. 

But there is a huge divide between climbers as to why this happens, and what to do about it.

So I did a dive into two threads sum up the debate perfectly. One climber posted about it on r/climbing, another on Mountain Project. Both threads land on the same two suspects: sizing and sweat.

Is It climbing shoe Sizing, Or Is It sweaty feet in climbing shoes?

The reddit poster had a pair of La Sportiva Solutions, sufficiently downsized, and worn in over months of regular sessions. The problem: a slipping foot inside the shoe on small holds and steep volumes, worse as the session went on.

The first wave of replies went straight to sizing.

Many climbers argue that beginners buying aggressive, downturned shoes often size them wrong from the start. They and suggested a flatter-lasted shoe like an Anasazi would be easier to fit correctly. Another pointed out that downsizing isn't one-size-fits-all across brands. Different shoes fit different foot shapes, so the same size reduction that eliminates dead space in one model won't necessarily work in another.

But one reply broke from the sizing consensus entirely. That commenter argued the slip wasn't a fit problem at all. They said it was actually because the sweat in their shoe was making their feet slip.

That's the split. Sizing gets blamed first because it's the obvious variable. But sizing doesn't explain why the slip shows up mid-session and gets worse over time. A climbing shoe that's the wrong size slips from the first foot placement. A shoe that slips more as the session goes on points to something building up inside it, not something wrong with the shoe itself.

Slimy feet in climbing shoes

The Mountain Project poster described the same pattern almost word for word (although they made a funny rhyme out of it..."Feet get slimy while doing the climby.") 

The suggestions in that thread ran the full range. Several climbers pointed to cleaning the shoes themselves, soaking leather in warm water or running synthetics through a wash cycle to clear out built-up residue.

Others suggested stiffer shoes, on the logic that a softer last gets worse the more it warms up. One climber described using a foot antiperspirant made for hyperhidrosis, applied the night before a session, to cut down on sweat at the source.

But the most repeated answer in that thread, by a wide margin, was socks. One climber wrote that switching to socks kept shoes from getting sweaty in the summer, stopped them from smelling, and made his feet warmer in winter. He said he wears socks every session, no exceptions. Another pointed out that a thin sock doesn't change precision since your foot is already separated from the rock by rubber and leather regardless.

Why "Just Buy Smaller Shoes" Doesn't Fix It

Sizing advice isn't wrong. A shoe with too much dead space will always feel loose. But most climbers posting about slip aren't describing looseness. They're describing a shoe that fit fine at the start of the session and started sliding an hour in. That's a moisture problem showing up as a fit problem, and no amount of downsizing solves it.

If anything, a tighter shoe traps more heat and produces more sweat, which makes the slip worse, not better.

Cleaning your shoes and drying them between sessions helps for the same reason drying your shoes helps with stink. It resets the starting point. But it doesn't do anything about the sweat your feet produce once you're thirty minutes into a session. Antiperspirant manages that better, cutting down sweat at the source before you even lace up.

Climbing socks to the rescue

Both threads land on socks as the answer that solves the problem while it's happening, not before or after. A sock sits between your foot and the shoe's lining and does two things at once: it wicks the sweat away from your skin. And it gives your foot something with grip to hold onto instead of sliding against slick, sweat-soaked material.

Endless threads on reddit, facebook, and other forums preach socks as the best solution slippery shoes. 

So no, its not always that your shoes don't fit right. Even a perfectly sized, freshly cleaned shoe can become slippery an hour into a session because your foot is sweating inside it right now. A sock built specifically for climbing manages that moisture with quick dry materials. And using micro grippy threads they keep your foot locked against the shoe instead of shifting a centimeter every time you weight a small edge.

The climbers in both threads figured this out the hard way, through trial and error across different shoes and sizes. The short version of what they landed on: if your feet are slipping mid-session and getting worse as you climb, it's likely not your shoe size. It's what's happening inside the shoe, and a sock built for the job solves it better than anything else in either thread!