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2011-10-14 2:50 PM
in reply to: #3724416

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Subject: RE: Brooks Pure Project?

mango6383 - 2011-10-14 2:12 PM This may be a silly question, but how do you figure out the heel to toe drop on a pair of shoes?  I looked up my new Ghost 4s and couldn't find the info on their website.

I check Runningwarehouse.com. Notice that the numbers are different from Runner's World.

Brooks Ghost 4

Weight: 10.0 oz (size 8)

Stack Height: Heel (30mm), Forefoot (18mm)

 



2011-10-14 2:57 PM
in reply to: #3724416

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Subject: RE: Brooks Pure Project?

How is drop figured?

When I review a shoe I measure the thickness of the sole from inside the shoe on the heel bed to the outsole. Then, I remove the laces, pull back the tongue and use the calipers to measure the forefoot thickness from the middle of sole parallel to where the metatarsil sits.

Subtract the smaller (forefoot) number from the larger (heel) number and there is your unloaded drop.

But be careful: Different midsole materials compress at different rates depending on their durometer. A full EVA midsole will compress at about the same rate heel to toe, but add in denser foam at the heel and the rate of effective compression on foot strike changes completely. That changes the geometry of the shoe.

A shoe doesn't "run" how it looks sitting onthe shelf. The dimensions and geometry of the shoe change dramatically as the foot strikes the ground, exerting a number of "G"'s of impact force and deforming the sole.

For that reason the wisdom of comparing shoe drp geometries has to be tempered against an understanding of the materials used in the midsole and their real-world compression under load.

Look at the change in the sole of this shoe I photographed a few weeks ago through a gait cycle:

 

2011-10-14 3:30 PM
in reply to: #3724482

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Subject: RE: Brooks Pure Project?
Tom Demerly. - 2011-10-14 12:57 PM

How is drop figured?

When I review a shoe I measure the thickness of the sole from inside the shoe on the heel bed to the outsole. Then, I remove the laces, pull back the tongue and use the calipers to measure the forefoot thickness from the middle of sole parallel to where the metatarsil sits.

Subtract the smaller (forefoot) number from the larger (heel) number and there is your unloaded drop.

But be careful: Different midsole materials compress at different rates depending on their durometer. A full EVA midsole will compress at about the same rate heel to toe, but add in denser foam at the heel and the rate of effective compression on foot strike changes completely. That changes the geometry of the shoe.

A shoe doesn't "run" how it looks sitting onthe shelf. The dimensions and geometry of the shoe change dramatically as the foot strikes the ground, exerting a number of "G"'s of impact force and deforming the sole.

For that reason the wisdom of comparing shoe drp geometries has to be tempered against an understanding of the materials used in the midsole and their real-world compression under load.

Look at the change in the sole of this shoe I photographed a few weeks ago through a gait cycle:

 

My GAWD Tom... That has to be some of the worst overstriding in that example I've ever seen. And this is what the low-drop shoes are trying to facilitate -- getting away from the overstriding.

2011-10-14 10:47 PM
in reply to: #3721649

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Subject: RE: Brooks Pure Project?
So I had a chance to try on three of the four PureProject models tonight at Road Runner Sports, and I'll have to admit that they weren't as narrow as my initial impressions Kfrom photos) suggested. That's not to say they work for me, as they have the same issue I've had with most brands -- the inward sweep at the little toe comes too soon, and my toes want to push out over the edge of the midsole. If you like shoes like the Saucojy Kinvara, these will be worth a look.
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