I have subtly been an Adidas fan for some time now. The Adidas Tempo 5 remains one of my favorite trainer/racers and if they still made them, would be my go to shoe for tempos and distance races. The unboosted Adios 2 remains a favorite for long workouts and trail races (I still have a few pairs). The Adidas Takumi Sen and Ren 1 and 2 will forever be one of my favorite racers. Yet I have had some trouble with the boost. I have enjoyed training recently in the Adidas Supernova, but likely due to the wider base which can offset the occasional unstable feeling of the Boost. I always hoped Adidas would firm the Boost up a bit to give it a more stable feeling and always wished the Adios or Takumi series would be just a bit lighter. My pair of Sen 1 and 2s are long gone, so looking for a favorite 5k-10k racer has been difficult... until the Sub2 came along. I had been talking with various contacts about this shoe for over a year and was very interested to see what Adidas was going to produce in the race to the sub 2 hour marathon. Now that it is here, is it the Sub2 shoe? Well.. let's talk.
Specs (per Running Warehouse)
Weight: 5.5 oz
Drop: 6mm (21mm/15mm)
Classification: Racing Flat
Upper/Fit
The Adidas Adizero Sub2 has a very different upper from most Adidas shoes. A full mesh upper is utilized that is thin, snug, but a little more anatomic than normal. The mesh is almost see through, but has internal reinforcements at the midfoot (via the three stripes internally). There is a mild heel counter that does not come all the way up, so the Achilles tendon clears it and should not cause problems. The heel counter is flexible and has not caused me any issues. There is a very mild and soft internal toe guard that I almost didn't notice, so that should not cause any issues.
The fit is very true to size. I would definitely not order smaller and some may need to order a half size up if wearing thick socks. I wear thin socks and have found them to fit snug and spot on in a size 10 (my normal size for running shoes). Overall the upper is simple but effective, which is definitely the theme for this shoe!
Sole
This is where things get interesting. The Sub2 debuts the Boost Lite, which is a far lighter and firmer version of the traditional Boost. It is still very responsive, but is noticeably firmer. The Boost lite runs the entire length of shoe and makes up the entirety of the midsole (no EVA here). There is a full length and full ground contact Continental outsole that provides great durability and traction.
Speed/Ride
The Sub2 is very fast at high speeds. This is not a shoe you use for jogging or easy runs. The firmer Boost Lite responds well at mile pace up to half marathon pace for me. I have used it for track workouts and some short tempos and will replace all my 5k-10k shoes. I thought there would not be enough shoe for longer workouts, but the Boost Lite is surprisingly protective despite how light the shoe is. The 6mm drop not too low and seems to be my sweet spot for most racing shoes, but for me is a a little too low for marathon racing. For the half marathon it would be a tough call between this and the 361 Feisu (REVIEW)
Given that there is no plate and only boost, the Sub2 is flexible. There are some very mild flex grooves throughout the shoe that allow motion but still keep some stiffness (also thanks to the Boost Lite) to make the shoe pop off the ground. The Boost Lite is awesome and I wish this had been integrated into more Adidas racing shoes earlier. It is firmer and far more stable than traditional Boost, making running fast easy in this shoe. The shoe is very stable overall due to the slightly wider sole last. There is no major narrowing at the midfoot and instead the width from the heel continues then broadens into the forefoot. There is good heel bevel at the posterior lateral aspect of the shoe that very much smooths out landings back there. The Boost Lite does extend beyond the foot, which would normally create a flare but it curves back under the shoe, creating a slightly wider sole and reducing flare at the same time. Again another subtle way to create stability. There is some toe spring, but it is mild compared to most Adidas shoes (especially the Adios 3 REVIEW)
Outsole/Durability
Adidas typically uses Continental rubber for their outsoles and this usually (the Ultra Boost is an exception) makes for great durability. The Sub2 is no exception, even at 5.5 ounces. After 21 miles I am seeing almost no wear and expect to get 200 miles out of this shoe or possibly more despite being a racing flat.
Thoughts as a DPT
I am very impressed at how responsive the ride of the Sub2 is just using Boost Lite and no shank or plate. This shoe is very fast when the speed picks up. The lack of a plate or shank means the shoe will not restrict the foot in any major spot, particularly the metatarsal and phalangeal joints. The stability is made up for with the wider last, full ground contact outsole, firmer Boost and a midsole that extends slightly beyond the foot without being a flare (because it rounds back down under the foot).
This shoe has done everything right that I could have asked for. There is a slightly more anatomic last without being clown like while maintaining that snug racing flat feel. The toebox is more rounded at the lateral forefoot and is slightly straighter along the big toe. There is some decent but not overdone heel bevel at the posterior lateral aspect of the heel. The Boost Lite and midsole sits slightly wider than the upper/foot position, but is lightly curved to minimize any major sole flare. There is a heel counter but it stays low and is somewhat flexible. The whole shoe is flexible, especially in the forefoot. However it is not so much that it qualifies as a minimal shoe, so there is enough stiffness to still be fast. The shoe last is stable as the midfoot is not overly narrow and maintains the same width from the heel, then expanding into a wider forefoot. I do not know why this is so hard, but that last part is one of my favorite things (other than the lightweight, boost lite, awesome fit and responsive ride). So many companies overly narrow the midfoot, which by default makes it more unstable.
So like my previous review of the 361 Feisu, I am happy Adidas decided to do something simple but very effective. The Boost Lite is firmer than traditional Boost, so still as responsive but far more stable. But that is it for major technologies other than a great fitting, lightweight racer. Just making simple better.
Conclusion
I am a huge fan of the Adidas Adizero Sub2. I see it more as a 5k to half marathon shoe at most due to the 5.5 oz, 6mm drop and ride, but many will be able to take it to the marathon. I would really like to to see Boost Lite integrated into the Adios. The Adios can definitely be lighter (Streak 6, Vaporfly are over an ounce lighter) and I think the firmer Boost Lite combined with a similar mesh upper would make a more stable, lighter and better fitting shoe. The women's half marathon world record was recently set in this shoe and I can understand why. This is one of my favorite shorter distance racers from Adidas and I am happy they now have such a good 5k-half marathon flat after the disappointment of the Takumi Sen 3. Looking forward to further racing and trainer development from them!
Thanks for reading!
Editor's Note: As always, the views presented on this website belong to myself or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your local running physical therapist. If you are in the Los Angeles area, I am currently taking clients for running evaluations.
Dr. Matthew Klein, PT, DPT
Doctor of Physical Therapy
Kaiser SoCal Manual Therapy and Sport Fellow
Doctor of Physical Therapy
Kaiser SoCal Manual Therapy and Sport Fellow
***Disclaimer: These shoes were a personal purchase from Running Warehouse and were purchased at their full US retail price. . We put at least 50-75 miles on trainers and 10-25 miles on racing flats prior to reviewing them. Currently I had 21 miles on my pair. My views are based on my extensive history in the footwear industry and years testing and developing footwear. If you are a footwear rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.
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