I love when brands listen to their customers. Seriously. Often it seems that, rather than listening, brands poo-poo what people say and revert to thinking that they know best and that’s that. In the case of the new ISO Series from Saucony, the brand seems to have paid close attention to the 2013 Running USA National Runner Survey that showed a whopping 92% of those surveyed saying “fit” was the most important thing to their running shoe purchases. Today, we’re going to review at the Saucony Zealot ISO – which some say is a “Cortana Killer” – and we’ll see if the brand has been able to continue its winning streak of innovation.

Saucony Zealot ISO Review - GearistOUTSOLE

Starting at the rear of the shoe, from the very back extending roughly a third of the way up the lateral side of the sole, the Saucony Zealot sports three pods of XT-900 rubber for durability in this high-friction area. On the adjacent, medial side there is a kind of rounded triangle frame of the same material presumably there just to balance out wear for those that may land extremely evenly on the rear of the shoe. The front two-thirds of the Zealot are made from Saucony’s IBR+ (Injection Blown Rubber) divided into well defined rows, each separated by deep flex-grooves that extend well into the midsole. Medially, the bulk of the rear two-thirds of the shoe (see image) is made up of exposed EVA (PWRGRID+).

Right away I should mention that the durability of the Saucony Zealot ISO is fantastic. At 30 (running) miles, both the XT-900 and the IBR+ show almost no wear at all points of the shoe. The rubber, on all fronts, is also very firm – which will come up later. I actually like this and think it adds a measure of traction to a shoe that has great utility. The next thing that I’ll mention – and which I’m really liking a ton – is the deep flex grooves that are all over the outsole of this shoe and carry over well into the midsole.


The stack heights on the Saucony Zealot are: 25mm in the heel and 21mm in the forefoot for a 4mm net drop. At use in the midsole is the new PWRGRID+; a material that Saucony Zealot ISO Review - GearistSaucony touts as having 20% more cushioning – part of the PWRGRID+ platform includes a small increase in stack height – and 15% more resiliency than PowerGrid. On the lateral, rear half of the shoe Saucony has put in an extended section of their SRC (Super Rebound Compound) to make for a smoother transition.

First, those flex grooves again – I really enjoy how deep the are and how much flexibility they give to the shoe. With that said though, the majority of the flexibility lies in the front half of the shoe while the amount of foam in the back half limits it not to the point of being completely inflexible (especially under load while running) but it just doesn’t give nearly as much as the arch – forward.

Now for the feel of the midsole. The Saucony Zealot is a bit of an oxymoron of sorts. This isn’t a bad thing by any means so I should clarify: The outsole firmness of this shoe, which provides such excellent durability and traction, seems to carry over into the feel of the midsole. So, what I’ve found is enough cushion that I think most runners who are looking for that plush feeling will get it, but once they’ve gotten to the load phase of their gait, they’ll find themselves with a more firm ride. If you’re a Kinvara devotee, I think you’ll really like the feel of the Zealot and find it a bit more firm.


While there are some really nice things going on in this shoe between the foot and the ground, the upper is the most talked about part of the Saucony Zealot – since it is a part of the Saucony ISO series and all!

The first thing I noticed about the upper of this shoe is that while there are bits of Saucony’s ubiquitous FLEXFILM in the forefoot, that’s pretty much it. The remainder of the structure of the shoe is much more traditional strapping. Now, to some this may seem to be a bit of a regression, but I don’t, it’s simply the best way to build this type of upper without compromising the Saucony Zealot ISO Review - Gearistdurability (for now). Before I explain what I mean by this, let’s round out the shoe construction. The forefoot area is made from a soft and breathable mesh which transitions into the core of the ISOFIT system. ISOFIT is made up of a stretchy, mesh sleeve that wraps the foot like a sock. There is no traditional “tongue” as it’s essentially seamlessly integrated with the sleeve itself. The collar of the shoe has a fairly minimal amount of foam and the heel counter is a semi-rigid, external “support frame” that does a nice job of locking down the heel.

Back to the ISOFIT system and why the strapping on the Saucony Zealot is more traditional: The way this system works is that the foot is held by the ISOFIT sleeve, which provides – to me – almost a physiological sensation of a good fit (more on the actual fit below). Now, the “feeling” of a good fit isn’t good enough to keep a shoe together so what comes next is an external “cage” which is where the bulk of the strapping comes in. Not connected to the sleeve since would likely limit hinder the feel and movement, the cage is actually “floating” and while things like FLEXFILM are definitely nice and light, Saucony has done a pretty good job of not making this a bulky setup. In fact, I think that down the road there could easily be a sort of cross-pollination of the PROLOCK system from the Kinvara 5 and this to make an even lighter-weight component.

Internally there are seams but they’re reasonably soft on the bare foot. Being someone who always runs in socks – and add to that the fact that it’s winter right now – I think that this might result in a couple of hotspots if you decided to go barefoot in them.


I’ve seen where some people say that this Saucony Zealot feels wide, especially in the forefoot, but I don’t see it. As I write this I’m literally sitting here with a Kinvara 5 on one foot and a Zealot ISO on the other and, if anything, the Kinvara 5 feels a hair wider. Now in the heel of the shoe, the fit is simple and doesn’t slide at all. Getting into the midfoot and the meat of the ISOFIT system, I do enjoy the sleeve/socklike feeling that’s going on. Again, I think that we’ll eventually see a melding of the PROLOCK system from the Kinvara 5 and the ISOFIT system. The floating “cage” that surrounds the sleeve is great if you do need to really cinch down on the foot (note: DON’T DO THAT) and held my foot in place nicely. The forefoot and toe box has plenty of of room for toe splay and does a nice job of shaping itself around the foot. As for sizing, the Zealot wasSaucony Zealot ISO Review - Gearist right in line with the other Saucony’s in my quiver at a size 11.


As I mentioned above, the ride of the Saucoy Zealot is cushy but with a nice touch of firmness. This makes for pretty solid ground feel and the deep flex grooves enhance that feeling. To me this is a shoe that could easily be a long-haul trainer and racer and I’d have no problem sinking a ton of miles into it. I do, however, think that when the speed kicks up, this shoe likes to get down. It feels like part of this is due to the less flexible rear half of the shoe which, when you’re really driving, drives back at you and gives a good amount of pop.


The Saucony Zealot weighs in a reasonable 9.4 ounces in my size 11. For comparison’s sake, the Saucony Kinvara 5 came in an ounce lighter at 8.4 ounces (granted, that Kinvara 5 had about 200 miles on it). is it the lightest thing you’ll ever try on? No, but it’s a solid daily trainer that would be just as at home racing. The price tag on the Zealot – which is available 2/1 – is a not-so-lightweight $130. While I would be more than willing to pay that for a shoe with tis ride and durability, I’d be tempted toward the Kinvara 5 which is $20 cheaper [or for $89.95 at Zappos and Road Runner].

The Saucony Zealot is an all-around very solid shoe. The technologies that reside in this shoe, including the ISOFIT system and PWRGRID+ are really very sound advancements and I think that we’ll see a lot more of them, and a lot more of the Zealot yet to come.

Although it’s not due out until February 1, 2015, you can get in on it now at Road Runner Sport by clicking the image below!

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