An admitted shoe geek waxes philosophical about running, triathlon, and life in general.
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Wednesday, January 5, 2011

If I were a shoe designer... Part 2

Working my way up the shoe, the next step is the midsole:

First, it would have a low heel-drop, 4mm or less. Sure, there's the Saucony Kinvara, a few Inov-8 models, and a few others that have that already. These also have their shortcomings. The Kinvara has a 4mm drop, but with the forefoot being perched atop lugs that are rather soft, I feel that the effective heel drop once the shoe is weighted is actually higher. GoLite has two models of zero drop, as well as Altra coming out in April, but I'm not necessarily sold that zero drop is the answer. Low drop, yes. Not that I have anything against zero drop, I just don't think that it's the ONLY way to go. I think the difference between zero and 4mm is negligible. Others, however, will disagree (most notable almost any one on the Born to Run forum). And why is this important? Two reasons: Getting the heel out of the way so you can midfoot land, and keeping the metatarsals more level with the ground (see my earlier post on Frieberg's Infraction, December 26th).

On top of that, I have a bit of a beef with the material used, and this has been so since the 1980's -- WHY are we still using EVA for running shoe midsoles? The only reason I can come up with is that the shoe companies want to build in "planned obsolescence", much the way the car companies did just after WWII -- when they cut the design life in half. EVA takes on compression-set very quickly, and the lighter the EVA (meaning more air in it), the faster it compresses. Yes, it's light, and can be cut rather than needing to be molded, so it's cheaper to use. Nike (and a very few notable exceptions) used urethane in several models, along with their Nike Air units. These things lasted a good long time. Even in the few racing shoes they made with urethane midsoles (the Mariah and the American Eagle), they LASTED. I put far more miles on the Nike Vortex (see picture at right) and the Columbia that I did on most other shoes simply because the midsoles didn't compress. So that's the HUGE difference I'd go to in a shoe -- using urethane in the midsole rather than EVA. I'd rather pay the slightly higher price for this feature more than ANY other. Maybe I'd lose my shirt making shoes that lasted so long, but I'd rather have customers that crowed my praises to the world on that one issue than sell 5 more pairs of shoes.

Heel flare is something that I've seen as non-essential. For a fore- or mid-foot landing, the heel comes down (or SHOULD come down) with a relaxed foot almost immediately after the initial strike. There is no need for a base wider than the heel itself.

Along with that, there shouldn't be a sharp edge to the bottom of the shoe on the outer edge of the forefoot. I see this in the New Balance Minimus Trail and the Merrell Barefoot shoes, and I think this is important in softening the lading on the outer edge, as well as easing the transition to the rest of the forefoot as the foot flattens.

Next up will be the footbed, insole, and last shape.

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