Running Shoe Construction - The Outsole
The strip of material which makes contact with the ground. Often refered to as the ‘Sole’ or ‘Grip’ of the shoe.
It's purpose…. Traction.
“these old things still have plenty of wear left”
The facts: The Outsole should only outlast the midsole, so at most it will have been tested to withstand 500 road miles. You may well find that the outsole still looks effective, long after the midsole has given up and no longer protects the foot from impact and potential damage.
The job of the outsole is gripping the floor enough for us to land, then push without slipping and losing drive.
There are various styles for traction over all kinds of surfaces, but no outsole can grip on everything as well as a specialised sole for a particular environment.
Sticky outsoles which grip brilliantly well, usually wear out the quickest. Harder wearing types will usually lose some traction in favour of greater lifespan.
A flat outsole will grip a flat surface brillaintly well, due to the maximum amount of friction. Broad flat studs will maintain a lot of contact, therefore a lot of friction.
Deepen those studs and you might find that they sink a certain way into softer ground. And the narrower they become, the better they will sink into the ground and therefore provide traction in wet ground and wet grass, which is one of the hardest surfaces to stick to.
There is, in all cases, a trade off between grip and wear resistance for any given surface.
So road shoes (below) employ a fairly flat outsole design with a lot of contact. They wear very slowly and evenly (unless you run on one part/the wrong part of your foot all of the time*).
Trail shoes (below) have a series of broad lugs with a variety of depths and in a lot of cases, multi-directional lugs that grip in all directions. They too will wear quite slowly, although the studs will grind down when used on tarmac, concrete or rocky trails in particular.
Fell shoes (below) have the most aggressive, spread out, narrow, long lugs which will dig into soft and loose terrain in order to allow people to claw their way up and down steep wet hillsides. The wear might be very slow if they’re used only on soft ground, such as mud or bog. Wet grass at the least, if not cross country on occasion. But on anything hard, the thin pieces of soft, sticky rubber will begin to tear and shave themselves flat in no time, leaving a healthy midsole perhaps, but a complete loss of traction where it counts.
There is of course no better way than to have a collection of footwear, allowing the choice between types, according to where you might be spending the most time on any given run. If it’s been wet, the studs will help on off-road routes. The wet road should still allow traction, but if it seems safer than aquaplaning, take the trail shoes and have the studs press through the surface water, with space between them for the water to escape. For outright prevention of unwanted slips ‘n’ slides, on steep ground or anything soaking wet and/or muddy, then the fell shoes ought to be the weapon of choice.
But there are a great many ‘hybrid’ shoes these days, with depth of cushion on top of a multi-directional outsole full of fairly deep lugs. These will never be a match for the speciality shoes in their appropriate environment, but they’ll allow the ‘explorers’ out there a freedom to run anywhere within reason and get away with it.
While buying one pair of ‘do-all’ shoes might seem a cost effective move, it’s our personal and professional opinion that owning a number of pairs allows a better choice of shoe for the task in hand. Twice as many last twice as long, if not longer for not damaging them on surfaces for which they were never intended. Not to mention, you’ll more often come away in one piece!
If you think you might need more traction, better value for money or more confidence in your footing, then feel free to call in to Accelerate to talk footwear.
Learn more about running shoes below
Grip VS Traction