The Biggest Myth About Hiking Shoe Tread, Busted by Science

Turn over one of your trail runners. Now do the same with one of your street sneakers, and set them side by side. You’ll notice one big difference right away: Where your everyday kicks are mostly flat, your trail shoes are rugged, studded with teeth around the forefoot and heel. That makes sense, because hiking trails are a wildly different surface than your average city sidewalk—rougher, looser, more demanding.

But are toothier lugs always the better choice for rough trails? To find out, I paid a visit to Adam Trenkamp, Outside’s gear test editor. In the Outside Lab at CU Denver, Adam strips down, cuts apart, and straps shoes into a variety of torture-testing machines to figure out how they work and where they perform best. I asked him for his take on what hikers should look for in an outsole; his response might surprise you.

Transcript

Adam Roy: What percentage of this outsole do you think you could eat before you had to go to the hospital?

Adam Trenkamp: Ooh, 1 percent? Well, before I had to go to the hospital or what would actually make me sick?

Adam Roy: I mean, how many do you think…if we had a contest right now, like a drinking contest, but it was a contest to see who could eat the most rubber, how much do you think you could handle?

Adam Trenkamp: I think I could get 50 percent before I had to go to the hospital, but that’s because I’m moving fast.

Adam Roy: So Adam, are you ready to bust some myths about shoes?

Adam Trenkamp: Adam, I’m ready to bust some myths.

Adam Roy: We do a lot of testing at Backpacker. I personally spend a lot of time on the trail. Our other editors and our testers do as well. But field tests don’t tell you the whole story. Even the most experienced among us still hold some misconceptions, let’s say about how gear works. There’s one way to bust misconceptions, that is the cold, hard light of science. That is why I’m here at the Outside Lab at CU Denver with my colleague, Outside’s lab test editor, Adam Trenkamp. Now, Adam is a mechanical engineer, unlike me, that means he is a man of science. And he spends all of his time breaking equipment here in the lab so he can give us the lowdown on what works and what doesn’t. Adam, how are you doing today?

Adam Trenkamp: Good, how are you? Great to have you here today.

Adam Roy: Great to be here. So, my question is about footwear. A lot of people look at the tread on footwear and assume that the more toothy the pattern is on the bottom of a shoe or boot, the better it’s going to grip in loose conditions on the trail. What do you think about that?

Adam Trenkamp: Yeah, so that’s a great question. I understand the thought process behind that. So grip really comes down to the type of trail surface you’re going to be on. It’s not necessarily all about the lug pattern itself, it’s how does that lug pattern pair with the trail surface. So one example of that is the Topo Traverse, which is a little more of a trail runner. It has a bit of a directional tread, similar to a mountain bike tire. So it’s there to kind of help you claw forward and give that grip, digging into a little more loose dirt, maybe some loose rock. So in this instance, a deeper lug on a looser surface is going to be a good option for traction.

Adam Roy: Why don’t you tell me a little bit about where something like this might not be optimal?

Adam Trenkamp: Yeah, so something like the Topo Traverse that has this kind of deeper, wider set lug pattern to shed dirt. This may not be as good on things like slickrock in Moab or other smooth surfaces like that where putting down a lot of rubber to increase your traction and increase your friction is better grip. That’s where this is maybe not optimal. Doesn’t mean it doesn’t work, it’s just there’s going to be better options for that.

That leads us in perfectly to something like the Astral TR1 Mesh. This is a little bit more of a water shoe, but as you can see, it has some sipes in the grips to shed water, especially if you’re thinking hiking along a river or river crossings, boat, paddle boarding, anything of that nature, but even on the trail as well. But what this does have that’s great compared to the Topo is a lot of rubber being put down. So the lugs are very close together, not a lot of big gaps in the sipes. That allows you to put a lot more rubber down to create more friction, which this would give you better grip on things like slickrock or smoother surfaces, especially those that are hard. That’s where something like the TR1 Mesh is going to be a great shoe.

Adam Roy: So what about something like a hiking boot? Can you talk a little about how the tread on that might differ from something like the Topo and why that’s important?

Adam Trenkamp: Yeah, so something like the Lowa Trek Evo hiking boot here is going to be a little bit different from the Topo and how it has deeper lugs that aren’t really directional. They’re kind of just placed throughout to give you grip as you place your foot. Sometimes on trail, there’s some really awkward moments or awkward foot placements, especially with loose dirt or if you have a heavy pack on. You really want multi-directional support and that’s where a traditional hiking boot is going to focus a little more on that. So still toothy, but unlike a trail runner, it’s going to move those lugs a little closer together to try to marry the best of both worlds. Some good grip on rock, smooth surfaces, but also still some lugs to dig into loose surfaces. Less focus on direction, but still able to shed dirt and put a lot of friction down.

Adam Roy: Well, it sounds like the bottom line is there really is no one shoe that can master any conditions. Hikers have to think a lot about what kind of surfaces they’re going to be hiking on when they buy their shoes.

Adam Trenkamp: Yeah, I would say that is a great synopsis. Really you can find one that can do good in a lot of areas, but it’s not going to be the best at any one for grip. So if you spend a lot of time on one surface, maybe it’s best to look for a shoe that specializes in that. But if you’re somebody who wants one boot or hiking shoe to kind of get you across all the surface types, it’s really important to look for something with closely spaced lug pattern, but still maybe deep enough that it can dig into some loose dirt and rock.

Adam Roy: As an editor at Backpacker, I have too many shoes. I think my closet is full to bursting at this point. But I’m wondering, you know, as someone who recreates in Colorado, how many pairs of shoes do you think someone would need to have to really cover all eventualities if you wanted to really get granular on the best shoe for every surface?

Adam Trenkamp: I think pretty much everybody in a state like Colorado can get away with two. You want something that’s going to have really good grip on rock, maybe wet, and then you want something for those looser trail surfaces and dirt when it’s, you know, maybe shoulder season and things haven’t quite firmed up yet. Me personally, I like to have a third, and it comes less around the grip and more around the actual support of the boot.

Adam Roy: So, obviously there’s one big factor in shoe grip that we have not talked about and that’s the kind of rubber on the bottom of the shoe. How much does that matter?

Adam Trenkamp: Rubber compound matters a lot when it comes to grip, especially on things like rock or other hard surfaces. The softer the rubber compound is, the more it’s essentially able to squish and create friction. That leads to better grip. But if you’re on a hard trail surface, a softer compound’s actually going to play into grip. It’s a weird line to walk. Some shoe companies you’ll actually see use dual compound rubbers where some lugs on the bottom will be harder and maybe even a taller lug or a different shape to dig into soft surfaces and some will be a slightly softer rubber or a flatter, wider lug to give you better grip on hard. That’s trying to give you the best of both worlds. So rubber compound also really, really important and it comes down again, trail surface. What type of surface are you going to be on?

Adam Roy: So I imagine that change in softness versus hardness has a lot to do with durability, how long you’re going to get out of that shoe.

Adam Trenkamp: Yeah, great point. A softer rubber is going to break down faster. So it is going to give you better grip, but it’s also going to break down a lot quicker, just the nature of it. The harder it is, the tougher it’s going to be. Think car tires or mountain bike tires as well.

Adam Roy: So Adam, give me the TLDR. What should backpackers keep in mind when it comes to the outsole of their shoes when they’re shopping?

Adam Trenkamp: Yeah, so the top things are definitely going to be what trail surface are you going to spend your most time on. So that’s going to be both your lug pattern, how wide the spacing between the lugs is. If it’s a loose surface, you want it to be a little more spaced and bigger lugs. If it’s going to be a smoother rocky, hard surface, you want closer together lugs to put more rubber down. Softer rubber for smooth hard surfaces, harder rubber for really soft surfaces to dig in.

Adam Roy: Well, thanks a lot Adam. It sounds like it’s a lot more complicated than some people think. Now I’m going to have to go home, turn all my shoes over and ponder the tread pattern.

Adam Trenkamp: Yeah, I’m here to give you way more information than you thought you ever needed, but I hope it actually helps.