The popularization of barefoot running has brought forth an interesting contradiction, namely that we need shoes to run barefoot. One could argue that this idea is supported first and foremost by shoe companies wanting to capitalize on a trend and sell more product or by consumers who acknowledge the benefits of running unshod yet would rather not get their feet dirty. However, I’d like to believe that even the most dedicated barefoot runner would come to recognize the inadequacy of the bare human foot in certain environments and subsequently affirm the benefits that a well designed shoe could provide- a shoe that functions not as a hindrance but rather as an extension of the body, an enhancement of its natural features. Surfers use wetsuits, alpinists use crampons both of which are good illustrations of an appropriate use of technology whereby we use creative thinking to make up for our physical shortcomings. This helps us become more proficient in the given environment without severely compromising the purity of the endeavour. To be a truly necessary piece of equipment, crampons cannot be blunt and a wetsuit cannot be made out of cotton. In a similar manner, shoes and more specifically those dedicated to running trails and mountains, need to hold certain design characteristics to make them not only a worthwhile tool for added comfort but an enabler for an enhanced experience. The following highlights some of the key features that I find provide for a well designed trail and mountain running shoe based on the current materials, technology and general approach used in footwear manufacturing.
El Capitain - whittling away
One of the more pleasing aspects to have come out of the recent explosion in minimalist footwear development, is a real focus in trying to reduce the overall weight of trail running shoes. Simply put weight matters and a good shoe has to be light. The foot represents roughly 2% of our overall body weight so unshod, we carry a very small amount of weight on our extremities. The heavier the shoe, the more the load creates a sort of pendulum effect interfering with our natural running motion, making us less precise and agile, not to mention less efficient, particularly on the uphills. However, a reduction in the weight of the shoe should not be to the detriment of other necessary features such as underfoot protection, durability and responsiveness (which I will get to later) but rather an effort to find the best possible balance of each of these characteristics in the lightest possible package. With the customary mix of rubber, foam and mesh, I find that the ideal weight of a trail running shoe should be between 6 to 8oz, with an acceptable weight being between 8 to 10oz and this only if the added features are of significant benefit to warrant the extra weight (such as reinforced overlays for durability). For the most part its hard to find a shoe under 6oz that will be really worthwhile in the mountains since at that weight, adequate underfoot protection is often compromised or the uppers are simply too light to withstand any beating. On the other end, a shoe over 10oz is clearly overbuilt and its weight will inevitably effect the overall efficiency of the running motion.
Being the first point of contact with the ground and since the mountains offer such a wide variety of surfaces to contend with, the outsole is probably the most notable feature differentiating a trail shoe from a road shoe. Hardpack dirt, sand, mud, roots, rocks, scree, snow, ice, all call for different types of outsoles, so the challenge in design is to decide whether to be very specific or shoot for an all-rounder. When I lived in the Pacific Northwest, the choice was pretty simple: a fell running type shoe in the winter, with agressive lugs for superior traction in the mud and a road flat for the summer for dry, harpack conditions was more than adequate. However, in Colorado, things are quite different. In the winter, I can start a run on dry trails, dart through the trees and hit a long stretch of solid ice, followed by some snow melt causing slushy and often muddy conditions and then scramble up a ridge on some loose shale only to then cross a section of road to connect to another trail. The summers offer little reprieve in these variations with sudden changes in weather making a nice run in sun turn into a skate-ski session down a talus field on the Continental Divide. Here versatility primes over specificity and while an all-round tread is not perfect for all conditions, a good design can make it reasonably well suited for just about anything. The ideal tread configuration would have medium sized lugs, shaped or slanted (towards the heel) to allow both forward traction and lateral grip, be few in number with rather generous spacing to avoid mud clogging and be only placed under the direct footstrike contact points to reduce weight (so no lugs in the arch). The rubber compound needs to be sticky to grip both dry and wet rock but not exceedingly so that it wears down prematurely or doesn’t give or allow any “float” causing breaking on downhills . Overall, this is a tricky balance to achieve and very few companies on the market right now have it right.
The piece of foam wedged between the outsole and the upper is unquestionably the feature in running shoes that is currently subject to the most debate. The main points of contention revolve around heel to toe differential and proprioception, with traditional trail shoes baring thick soles and raised heels to provide cushioning upon impact and barefoot running shoes being very thin and having little to no drop, relying on the body to naturally absorb shock. While I’m an advocate for the latter, all the talk about heel height and increasing ground feel seems to have detracted from the vital role the midsole plays in “giving life” to the shoe. What I mean by this, is that having a thin zero drop midsole simply isn’t enough to make it good. The foam also has to be responsive and provide protection otherwise it is rendered completely useless and it would be best to forgo it altogether.
So what makes a midsole responsive and not simply a “dead” piece of foam? There are many pictures of minimalist running shoes rolled up in a ball demonstrating their flexibility. The bare foot does not “roll up” on itself so it is pointless for a shoe to do so.While a shoe does need to flex, it should only do so enough to accompany the foots natural motion but should also be able to dynamically snap back to its original shape, giving it a reactive feel. To achieve this, the durometer of the foam has to be quite firm and dense. Conveniently, a denser, firmer foam also provides more lateral stability (not a sloppy marshmallow feel) and better underfoot protection. Another way to do this is by inserting a rockplate in the forefoot which helps keep the midsole thin and low to the ground and contributes to enhancing both the responsive and protective properties of the shoe.
On a final note, the shoe’s last is also of importance. It should be fairly narrow in the heel, curved and broader in the forefoot to accompany the natural shape of the foot.
When I slip my foot into a shoe, I want it to feel like a second skin, with a close, precise fit (yet non constricting), breathable with few seems and no abrasive materials to cause hot spots or blistering. In addition to this, the upper of a trail shoe needs to provide lateral stability and be durable, all the while remaining light. While these features do not strike me as being unreasonable, it is incredibly hard to find a shoe on the market that meets all of these requirements.
Fell running shoes are typically the most precise fitting as they are usually cut on a very narrow last and have slim, minimal uppers. While this makes them ideal for edging and contouring, they become somewhat restrictive on longer races when the feet swell. It is not necessary to have a narrow shoe to achieve a precise fit and long term having the foot constricted in that manner will cause a general weakening of the tendons and muscles that can’t quite function as they should.
While I’m an advocate for a simple, uncluttered upper with little to no padding, I do think it needs a minimum of structure to be functional and last a while. A few overlays can work wonders in providing both lateral stability and added durability. The proper placement of these overlays is key. A thin rand of approximately 10 millimeters wide that wraps around the shoe will strengthen the weak connection between a mesh upper and the midsole. The rand can be cambered on both the medial and lateral side of the forefoot, in line with the first and fifth metatarsal and by the the big toe to address specific high “stress” points on the shoe while also adding support and protection. Additionally, a thin lining of a felt type material on the inside of the shoe provides seamless comfort while remaining breathable and preventing some of the trail debris from getting in.