Vibram Five Fingers KSO [Keep Stuff Out] — the Definitive Guide

By Justin Owings on Feb 26, 2010 | In Barefoot Shoes | 10 comments »

From left to right, black/orange KSO Vibram Five Fingers, blue camo KSOs, grey/palm KSOs
Above, a photo of three male color combinations of the Vibram Five Fingers KSOs (VFF KSO).

The KSO at a glance —

The Vibram Five Fingers KSO (thumbnail)

  • "KSO" stands for "Keep Stuff Out" due to it having a mesh covering over the top of the foot.
  • The KSO retails for $85 for both Men and Women.
  • Best-selling model for men — particularly all-black KSOs.
  • Used mostly for running and hiking, but is the "do anything and everything" Vibram model.

About the Vibram Five Fingers KSO

Straight from Vibram: the Five Fingers KSO features "A non-marking 3.5mm Vibram TC1 performance rubber sole is razor-siped for a sure grip, and a 2mm EVA midsole enhances plating protection and comfort."

The "razor-siped" rubber sole on the KSO is the standard, original VFF sole (same as with the Classic, Flow, and Sprint models). Razor siping is just little jagged cuts that expand when the Vibram rubber sole is bent or flexed. This can increase surface grip on many surfaces. That said, the standard VFF sole can be slippery in muddy conditions due to the lack of cleating (See the KSO Trek if you want a cleated sole)

The KSO's upper covers the foot up to the ankle preventing debris from getting inside the shoe. Of the standard soled Vibram models (Classic, KSO, Sprint, and Flow), only the Flow and KSO cover the top of the foot.

The KSO's 2mm of midsole is a distinguishing factor as compared to the Sprint and Classic, which have no midsole, and will reduce, if only slightly, the barefoot feel as compared to these models.

Finally, the Vibram Five Fingers KSO is secured to the foot by a single hook-and-loop system with a nylon strap that goes around the heel and is tightened via a velcro strapping mechanism on the top, instep of the foot. With only one velcro point, the KSO's attachment method is simpler than both the the Sprint's three-point and the Flow's two-point velcro attachment system. The primary drawback of this method is that it can cause wear in the nylon strap where it folds on either side of the foot.

Pros:

  • Covered, strapped design makes the KSO perform well in high-intensity applications, including watersports, while keeping out debris.
  • The KSO looks more like a "shoe" as compared to Sprints or Classics.
  • Can function as the only Vibrams you own, doing just about anything you can throw at them.

Cons:

  • Covered top makes putting them on more difficult; the difficulty is usually reduced with practice.
  • Covered top can reduce breath-ability, making your foot warmer than with the airier Sprints or open-topped Classics.
  • 2mm of additional EVA as compared to Sprint or Classic models will reduce ground feedback.

Performance:

Vibram Five Fingers KSOs can be used in virtually any application imaginable. They have been used for wear in moving water, for trail running as well as running on concrete or asphalt, for many fitness activities including weight lifting/training, climbing, hiking, biking, walking, etc. Others use them casually or for travelling. The VFF KSO is the jack-of-all trades Vibram Five Fingers model as depicted in story and photos in the many, many user stories and experiences running, hiking, traveling, below.

KSO Colors:

Men's KSOs are available in the following color combinations:

All black KSO Five Fingers for men Grey Green FiveFingers KSO for both men and women Blue Grey and Camouflage KSO Five Fingers for men Black Orange and Grey KSO Five Fingers for men Black Grey and Camouflage KSO Five Fingers for Men

Women's KSOs are available in the following color combinations:

All black KSO Five Fingers for women Grey Green FiveFingers KSO for women Blue Grey and Camouflage KSO Five Fingers for women Grey Agate and Camouflage KSO Five Fingers for women Grey and Pink KSO Five Fingers for women

Detailed KSO Vibram Five Fingers photos:

A photo of the black,grey, camouflage soled Vibram Five Fingers KSO for men A photo of the black,grey, camouflage soled Vibram Five Fingers KSO for men A photo of the agate, grey, camouflage soled Vibram Five Fingers KSO for women A photo of the agate, grey, camouflage soled Vibram Five Fingers KSO for women

Sizing:

Check out the definitive guide to sizing Vibram Five Fingers. Having perused that document and figured out your size, there are certain noteworthy considerations for the Vibram Five Fingers KSO:

  • Your size in KSOs may not correspond to your size in other VFF models, particularly Sprints and Classics. If you know your Sprint/Classic size, KSOs should size one down, though this is only a rule of thumb and your mileage may vary.
  • Generally, you should not need to size up to wear five-toed socks with the KSO.
  • If you have a high instep, you should give special consideration to trying on a pair of KSOs in person to insure proper fit. Some color combinations have been found to run tightter than others — specifically, the all black KSOs seem to be more snug on top of the foot. The same concern would apply if you have larger ankles.

Cleaning and care:

Machine-washable but air dry. Advanced stench may require white vinegar soaks or oxyclean treatment!

Modifications and other considerations:

Select reviews:

For more KSO reviews, check the comprehensive Five Fingers reviews list here.

Pro-tip — Get the KSO if you don't mind the added time to put them on and want the most versatile, can-do-anything Vibram Five Fingers model.

Where to buy

If you're shopping for Classic Five Fingers online, check out the major online retailers over at the BirthdayShoes Vibram virtual Store! Otherwise, find a local retailer via Vibram's store locater.

 

Vibram Five Fingers KSO User Experiences and Photos

Below are listed Vibram Five Fingers KSO user stories and reviews. Each link leads to a separate post written by a KSO user about their experiences with the KSO model. Stories cover many of the things VFFers are doing in their Vibram Five Fingers KSOs. Click around and see what you could be doing in the full-coverage barefoot alternative KSO!

Running —

Hiking —

Traveling —

Other —

About the Author — I founded BirthdayShoes.com in April 2009 on realizing just how much I enjoyed having "free feet" - I mostly wanted to use them for weights, sprints, and plyometrics (I'm not much of a runner!). I'm a Googler by day and minimalist footwear aficionado by night; you can find me 'round Atlanta. If you want to catch up with what I'm doing outside of the site here, follow me on twitter @bdayshoes or @justinno or check out my personal site JustinOwings.com.
has written 754 articles and 302 comments.
Tags: kso

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Comment from: Gabriel S [Visitor] Email
Gabriel SI did a five mile run in my kso felt great was easy
04/27/10 @ 20:53
Comment from: Michelle George [Visitor]
Michelle GeorgeI ran my first 10km fun run in my KSOs last weekend...they were great!
06/21/10 @ 23:23
Comment from: michael [Visitor] Email
michaelI have heard that in shorts kso's some times look like ankle socks is this true and if so is theur any thing you can do about it?
10/01/10 @ 19:53
Comment from: john [Visitor] Email
johni am 69 and my son gave a pair of KSO's for Christmas to use for fast walking. I have had planter's faciatias last year and am a little leary about using them. Any experience about using them for fast walking?
12/30/10 @ 11:41
Comment from: John Gunter [Visitor]
John GunterInjinji makes different length socks from micro to over-calf.

As with running, walking will require some break in time, not for the shoes but for your feet.
01/01/11 @ 21:23
Comment from: Linda F [Visitor]
Linda FLove my new KSO's! I'm a toe sock lover so I don't have a hard time getting them on. doesn't take me any longer to get them on and go than it does my running shoes.

I've been searching the site to find if there are any other people with a disability/injury that are using Vibram's and how it's going for them. Believe me I know how crazy it sounds, but the KSO's significantly reduce the pain in my dislocated knee. I dislocated it a week ago. Last Saturday night I was in tears from the pain. I hurt from my ankle to both hips and up into my back from compensating around the bum knee. I bought these Sunday afternoon at 4:00 pm and have worn them since (except for sleeping and showering)and the difference is amazing! I keep thinking I'm going to have pain the next morning from over wearing them, but it just hasn't happened. Of course I'm not running or doing jumping jacks, but I feel like I almost could. Which is just crazy. But can't wait until I get medical clearance to try!
02/08/11 @ 21:40
Comment from: Ernest P. Chock [Visitor]
Ernest P. ChockI bought the standard low cut 5-finger socks, and like them.
Am wondering if you also make some with open toes (for ventilation) and some with high cut, so that I can wear them as if it were a regular sock.
04/26/11 @ 16:37
Comment from: John [Visitor]
JohnThose with small fifth toes (pinkie toes) will not like these shoes. Impossible to fit.
05/25/11 @ 16:03
Comment from: Rodney N. [Visitor]
Rodney N.Just ordered my KSO grey/black/camo the other day, from my local REI. I can't wait for them to come in haha.
07/14/11 @ 18:07
Comment from: McKay [Visitor] Email
McKaySo im a size 46 in th kso, But i was wondering. I like to wear toe socks with my Skeletoes and was wondering if i should go to a size 47 to compinsate for the sock or if it will be fine as a 46. Please help me out! thanks
01/02/12 @ 19:19