Friday, April 06, 2018

adidas adizero Sub2-Analysis and First Runs Impressions Review: An Elegant, Hyper Light, Fast, and Comfortable Race Flat

Article by Sam Winebaum, Editor

adidas adizero Sub2 Review
Update: Read our In Depth Multi Tester Review here
Breaking 2, Sub2 the big brands have unleashed great athletes and innovative shoes in a marketing and athletic quest to break the magic two hour barrier. Nike lined up the VaporFly 4% a super cushioned flashy looking super cushioned racer with a carbon plate.  adidas has focused its contender , the adizero Sub2, on a subtle and elegant design, incredibly light weight, simplicity, Boost Light a new firmer, much lighter version of its Boost midsole foam, a very light, airy, deceivingly simple and subtle looking super supportive Microfit upper, and a single continuous slab of Continental Microweb outsole.

The contenders couldn't be more different in their approach! 

After a few short runs at varying paces are my initial impressions of the Sub2. A full in depth review with comparisons will follow.

Weight: 5.6 oz/159 g (size US 9)
Test Sample:154g 5.43 oz  (size US 8.5)
Stack Height 21 mm (Heel); 15 mm (Forefoot); includes non-removable sock liner
Unisex sizing
Price $180. Available now including Running Warehouse here

First Impressions and Fit
At first glance our black Sub2 looks like a  low slung, classy lifestyle shoe. with a low stack height, the white "3 Stripes", and only on the lateral side, and a mottled gray and white midsole.  There are no flashy indications this is a high performance racer.

The fit is sublime with no pressure points and is highly supportive, if light and easy feeling on the foot. I was true to size with plenty of well held mid foot and heel room. The toe is a touch short a in medium light socks but I would not size up. I was right between sizes, true to half size up, in the Adios Boost 1

When compared to the adios Boost 3 at the same size what is most noticeable, while it appears the last is the same, is the higher front toe box volume and increased comfort created by the elimination of the fairly thick suede overlays. 
The rest of the fit towards the rear is similar although overall slightly more relaxed, lower slung and lighter on the foot in the Sub2.  


The upper is what adi calls Microfit. It is made of a single layer of thin small holed fairly but not overly soft mesh. It is completely breathable and draining (m first run was in the rain and the shoe absorbed no water and drained completely) and this from toe to the beginning of the heel counter. Even the sides of the collar are open and breathable. But, there is much more to this apparently simple upper than meets the eye from the outside...

The single layer mesh is actually woven slightly denser on the inside than outside to create vertical bands of support towards the midfoot and rear and bands across the foot upfront. This differential weaving is totally invisible from the outside but can be seen holding the shoe to the light off the foot.
Further very thin underlays are located below the painted "3 Stripes" on the lateral side.
On the medial side a single external overlay with "adizero" printed on it is backed up inside with internal 3 strips as on the lateral side.
From the last 3 lace holes forward on both sides is a thin underlay panel,very thin  Forward along both sides of the toe box is a underlay with holes which raises the toe height. At the very front toe bumper the underlay may be ever so slightly stiffened.
The result is a very easily fitting light breathable upper with no apparent hot spots so far and a consistent secure fit and feel that doesn't squeeze the feet to pain as many race flats do. This by no means a wide upper but those with moderately wider feet seeking a race fit may find it quite accommodating. Although far less scratchy than the adios Boost 3 I would hesitate to run it barefoot for a long race.
The sockliner with drain venting holes is glued in.  The ankle and achilles collar is more than adequately padded as is the lightly padded tongue. Gone is the long, puffy, and slightly scratchy tongue of the adios Boost 3.
Both achilles and ankle collar  are considerably lower than the adios Boost 3 and on the foot a bit more relaxed in hold.
The Sub 2 has a conventional and relatively firm heel counter. The upper, as the saying goes, fits like a glove but not an overly snug one.

The Boost Light midsole, unlike its predecessor in the adios Boost with its EVA layers and Torsion plastic pieces to stabilize "uncaged" Boost is a totally different material. It is firmer without being harsh, much lighter than relatively heavy Boost, and most importantly clearly feels like it has less lateral deflection under load which in prior adi Boost racers required all those controlling, stabilizing elements.

Under load the feeling is firm, well controlled, and surprisingly shock and vibration reduced for such an incredible, low slung, light shoe. Very little of the jarring response of conventional race flats here, just a smooth fluid and firm response, of course aided by the outsole, the geometry  and the simplicity of the construction.
Unlike many race flats, and particularly Nike for me as they are so narrow at the heel, the geometry at the rear landing is broad with a chamfered heel, with slightly more midsole width bulge on the medial front of heel than lateral for a touch of stability.

Despite the very light weight, there is plenty of cushion for this heel striker for shorter race purposes. The mid foot feel is a bit thin, so mid foot landers may fatigue a bit there with the forefoot feel is surprisingly broad and well cushioned for me. This midsole would be a total winner and more versatile if it had a few millimeters more stack height.

Nike Zoom X in the VaporFly has a silky softer feel than Boost Light, tempered and controlled by the carbon plate. The Reebok Floatride series also has a somewhat less silky soft feel as its midsole has firm stiff EVA sidewalls.  With Boost Light I sense a firmer steadier, compression and rebound than Boost for sure and it seems a denser more stable under foot material than in the Vapor Fly and Reebok as there are no stabilizing pieces. I have to believe the midsole foam is made of PEBA as the VaporFly and the Reebok Flightride series but here looking closely Sub2's appears to be made of expanded pellets just as the original Boost was instead of melted and injected material as in the Reebok and Vapor Fly which would produce a smooth consistent surface. 

The outsole is a single slab of Continental rubber, the Microweb. It is thin and full coverage. It is hard to know how many miles it will last but generally even thin Continental outsoles are very durable. The single piece outsole in combination with the single piece midsole and no Torsion gives the shoe a flex very similar to the adios but a touch longer. While potentially slightly less stable at mid foot than the adios overall, I find the Sub2 pretty darn stable for such a light shoe and minimal upper.

Let's not be mistaken.  The Sub2 is a full blown racing shoe designed to get elites towards a Sub 2 in as light a shoe as possible. After all adi cut 2.3 oz /65 g from the weight of their previous flagship racer,and both men's and women's offical world record marathon shoe, the adios Boost. So don't expect the relative cush of either the adios or the VaporFly which comes in at approximately 6.8 oz, so 1.2 oz more than the Sub2.

What you will get is a snappy, very decently shock free ride in a very, very noticeably light shoe. So noticeably light that my old legs just seem to want to turn more easily in them and I sometimes wonder if I even have anything on my feet and look down to check!

I was surprised that even very slow warm up paces were relatively pleasant. As the pace picks up the transitions are very smooth and natural, fast and controlled but less explosive and also far less harsh and jarring than shoes with mid foot plates such as the Zoom Streak or GOmeb Speedt. Is it a ride that would get old me through a 3:30-4:00 marathon? I don't think so. Not quite enough shoe but if they added a few more millimeters to that magic midsole, yes. At 10K for sure it will be my pick over other race flats and maybe just maybe on a flat course for a half marathon replacing my VaporFly.

In the "Sub Breaking 2" arms race the contenders have lined up their racers and shoes. The adizero Sub2 takes the conventional race flat to a whole new level of refinement, comfort and incredibly light weight with state of the art materials and elegant thoughtful design. It so far a race flat I actually enjoy to run, which is rarely the case. Soon I plan to actually race it.   Our full review with comparisons will follow shortly.

Sam Winebaum is the Editor and Founder of RoadTrailRun. He has been running and shoe geeking for 45 years. As he turned 60 in 2017 he was thrilled to clock a 1:35.24 half.

For Sam's full run bios se our Reviewers Bio Page here.
The Sub2  was provided at no cost.The opinions herein are entirely the author's

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