Decoding Trail Industry Lingo with Vivobarefoot

Finding the right shoes for your needs can be challenging when trying to navigate barefoot industry jargon. 

As part of our goal to make selecting your next model as easy as possible, we want to give you the insider info we’ve collected to help guide your decisions.

This article will focus on trail shoe terminology. Specifically, the Vivobarefoot naming conventions, so you can decode their model names. We’ll also look into some other brands to help you distinguish between different outsoles for different uses.

Soft Ground (SG) vs Firm Ground (FG)

Vivobarefoot will often include “SG” or “FG” in the names of their trail models such as trail runners or hiking boots, as a way to distinguish between the different types of soles they make. The two types of soles are designed for use on different types of terrain.

The most noticeable differences between SG and FG is very quickly observed when looking at the tread on the shoe. You will notice differences in the shape of the individual lugs, the space between them, and the depth of the lugs.


(The Vivo Winter Tracker SG - An example of how SG lugs look)

SG refers to Soft Ground soles which, according to Vivobarefoot’s website, are “made for use on soft ground.” Generally, soft ground refers to grassy, snowy, slushy, and watery/muddy terrains. These are unstable surfaces.

The SG outsole design allows you to move confidently on softer terrains in a few ways. Firstly, the lugs are long and spiky, to help you “sink” into softer ground like muddy trails and grassy fields. Secondly, the chevron shaped lugs act like a claw to allow you to firmly dig into soft and unstable ground. 

It is still possible to use models with an SG sole on firmer terrains, but this runs the risk of the sole wearing out faster since the outsole materials are softer. Additionally, the surface area that comes into contact with hard ground like concrete is just the tip of the lugs, which can feel unstable on hard ground.


(The Vivo Primus Trail III All Weather FG - An example of how FG lugs look)

FG refers to Firm Ground soles which according to Vivobarefoot’s website are “made for use on firm ground. Suited to all terrains, [and] hard-wearing.” Generally, firm ground refers to rocky terrain, gravel roads, dry hard-packed dirt, and concrete terrains that are considered harder and tend to be more stable.

Unlike the SG, the lugs of the FG sole are created to provide you with more surface area by increasing the contact points with the ground. This makes the FG outsole design ideal for firmer grounds as more surface contact means more information going to your feet that you will use to navigate.

The shape of Vivobarefoot’s current FG lugs is often closer to an asterisk, and they are significantly shallower than the SG. The lugs are more numerous and packed closer together– again, to increase the overall surface area when coming in contact with the ground. FG soles are therefore ideal for firmer, more stable grounds such as city walking or walking on dirt roads where there’s less need for extra stability.

Based on Vivobarefoot’s recommendation, FG soles can be used in any terrain. While this is technically true, it is still worth considering an SG sole when planning on using shoes on more unstable terrain where extra grip would be useful to avoid slipping, falling or generally losing balance.  

What About Other Brands?

The trail shoes we carry from different suppliers such as Xero, Lems and Ahinsa also have soles that are suited for soft or hard ground, they just don’t label them with that information.

You can easily spot the difference between a trail shoe made for unstable and softer terrain compared to a trail shoe made for stable and firmer terrain by looking at the outsoles, but here’s a little cheat sheet for some of our popular models for Spring/Summer 2024


Xero provides a wide selection of trail footwear from sandals to boots to runners and watershoes.

One popular low-rise hiker/trail runner that we carry is the Mesa Trail WP. 

(XERO Mesa Trail - Another example of an SG sole)

Two main features visible here can give you a hint as to whether these are made for softer terrains or firmer terrains: if you guessed the lug depth and lug spacing then you’re getting the hang of things!

Soles with deeper lugs and wider spacing between them like the Mesa Trail WP tend to be best suited for soft terrains such as muddy trails, mucky parks, or sandy beaches: essentially any unstable sort of terrain where you want to dig in to get a good grip. 


Lems offers a great selection of trail hikers that are great for anyone looking for a more rugged leather hiking boot look.

(Lems Boulder Boot Grip- Another example of an FG sole)

A popular high-rise boot that is more commonly used as a casual fall boot and sometimes a hiker is the Boulder Boot Grip. Let’s look at the Grip.

The first thing you’ll probably notice is that there aren’t any distinct or deep lugs on the sole that would normally indicate that this boot would be suitable for softer terrains. The second thing you might also notice is the greater amount of surface area on the sole of the boot, which suggests this boot works better on firmer terrains. Based on just those two features, we can tell the Boulder Boot Grip is probably designed for firmer terrains such as dry dirt roads, hard concrete paths and rocky slopes. 


Another one of our brands that offers a trail shoe is Ahinsa with their Chitra Trail Runner. This is a trickier one to crack since just based on looks, it’s a little harder to tell whether it falls into a soft or firm sole. 

The lugs seem deeper than the Boulder Boot Grip but shallower than the Mesa Trail WP. In addition, just based on looks, it seems like there is more surface area than the Mesa Trail WP but less than the Boulder Boot Grip. Which one could it be?

(Ahinsa Chitra Trail - An example of an inbetween)

It’s both!

Luckily there are some models that offer a bit of both. It’ll have slightly deeper tread depth and slightly more surface area and so can work on both soft and firm terrains. This makes it a versatile trail shoe for those who walk all sorts of trails during different weather conditions.