Herzogenaurach’s three stripes company just released the state-of-the-art renovation of their popular UltraBOOST series. There is possibly no shoe in the assortment that feature so much of adidas’ soft and springy Boost material then this one. In addition to the iconic three lines, the material has been a trademark for adidas running shoes since its very first release in 2013. I had the chance to test one of the first pairs, the Adizero Adios Boost, back then. Check the Post if you are interested.

With the UltraBOOST series adidas has been surfing amid the so called “lifestyle” and “performance” segment. There are no two opinions about the look, that is for sure. Nonetheless we will concentrate on the performance part of things in this post.
As mentioned earlier on, the boost material is a trademarked polymer exclusively used by adidas. Basically, it is a lot of small balls which are compressed and molded to protect the foot from the ground and it delivers a certain boost while toeing off during the running movement. The small balls contain of patented thermoplastic urethane. Adidas cooperated with the German chemical powerhouse BASF (Hello Steffen 😉) to create this material.
Adidas did not hold back with the usage of the boost material. Particularly at the back end of the shoe. At first the Boost material was only known within the running scene, but when a certain Kanye Omari West was seen wearing a pair of UltraBOOST “Triple White” in 2015, the shoes went mainstream and not only boosted running strides but also sales.
The three stripes are an iconic characteristic that defines Adidas. At first the brand added the stripes to its running shoes to make them sturdier. One of the initial T&F athletes to use the shoes with the stripes was legendary Jesse Owens in the 1936 Summer Olympics. By now, the stripes on the clover symbol represent Adidas focus on variety. Finnish brand Karhu and Adidas used to share the three stripes but Adi Dassler bought the rights in 1952.
Comfort undoubtedly is a key feature with this shoe. The upper feels super pleasant and comfortable. The pattern on the side of the shoe make sure that enough stability is provided. I like the sock-like design and the wide flexible fit around the forefoot. The Ultraboost 21 upper is made from flexible Primeknit material and is only 1.9mm thick. Compared to a traditional upper, this really feels like a sock.
The last 7 years, the Boost material was a stable when it comes to cushioning. Several models have proofed this. Notwithstanding the age, the material is still good and certainly does the trick when it comes to the padding part. The energy return was lacking in previous models and adidas successfully changed this with this model and the newly developed LEP Torsion System. The Torsion system is something that can been seen in older models but adidas changed it quite a bit and added the flexible TPU fork to increase the toe off.
A new standard is the Continental rubber that is used on the outsole of the shoe. Its durable and grips pretty well.
Two german tradional companies unite. Continental was founded in 1871 as a rubber producer and still is strong in this segment producing all kinds of tires and car equipment.
It is no top-secret that the Ultraboost 21 is not the lightest shoe. With a weight of nearly 380 grams in my US13 model it is weighty for its standard. Nevertheless, it doesn’t feel super heavy or unsmooth while running. The feeling was normal and I never felt I have to invest more energy then I essentially got out of the shoe. According to adidas, the Boost foam in this shoe is now firmer. This should result 20% more responsiveness.
A close up shot highlighting the Primeknit upper that is made of yarn from recycled plastic bottles.
It looks like the heel is one gigantic portion of Boost foam with one major drop. With 10mm, it is not that huge at the end. The heel foam is wrinkled around the cup of the heel and produces a setup that allows the foot to sit securely inside the midsole. This is a major change to the previous version, the Ultraboost ST.
To me the Ultraboost 21 is a daily milage grinder. I really treasure the fit and the padding it offers. I use this shoe on a daily basis to get the base miles in the tank. I like the fit the reliability of the boost material that certainly doesn’t disappoint. With the arrival of the Lightstrike and Lightstrike Pro material it will be exitng to see what the future holds for this modell range. Boost is the heaviest of the current three Adidas performance foams and it will be interesting to see how the brand develops or include these materials further.

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