Meet us in the hot pursuit of the pinnacle harmonisation of weight, cushioning and responsiveness in Adidas Men’s Ultraboost 21 Shoes. Say hello to incredible energy return. Sock-like fit Adidas Primeknit+ textile upper Boost midsole Textile lining 10mm midsole drop Continental rubber outsole Lace-up closure Primeblue fabric Adidas lep The new Torsion System provides a 15% increase in forefoot bending stiffness for a more responsive run. Incredible energy return 6% more Boost capsules ready to explode with energy in each step. Primeblue fabric This product is made with Primeblue, a high-performance recycled material.
Meet us in the hot pursuit of the pinnacle harmonisation of weight, cushioning and responsiveness in Adidas Men’s Ultraboost 21 Shoes. Say hello to incredible energy return. Sock-like fit Adidas Primeknit+ textile upper Boost midsole Textile lining 10mm midsole drop Continental rubber outsole Lace-up closure Primeblue fabric Adidas lep The new Torsion System provides a 15% increase in forefoot bending stiffness for a more responsive run. Incredible energy return 6% more Boost capsules ready to explode with energy in each step. Primeblue fabric This product is made with Primeblue, a high-performance recycled material.
Meet us in the hot pursuit of the pinnacle harmonisation of weight, cushioning and responsiveness in Adidas Men’s Ultraboost 21 Shoes. Say hello to incredible energy return. Sock-like fit Adidas Primeknit+ textile upper Boost midsole Textile lining 10mm midsole drop Continental rubber outsole Lace-up closure Primeblue fabric Adidas lep The new Torsion System provides a 15% increase in forefoot bending stiffness for a more responsive run. Incredible energy return 6% more Boost capsules ready to explode with energy in each step. Primeblue fabric This product is made with Primeblue, a high-performance recycled material.
Meet us in the hot pursuit of the pinnacle harmonisation of weight, cushioning and responsiveness in Adidas Men’s Ultraboost 21 Shoes. Say hello to incredible energy return. Sock-like fit Adidas Primeknit+ textile upper Boost midsole Textile lining 10mm midsole drop Continental rubber outsole Lace-up closure Primeblue fabric Adidas lep The new Torsion System provides a 15% increase in forefoot bending stiffness for a more responsive run. Incredible energy return 6% more Boost capsules ready to explode with energy in each step. Primeblue fabric This product is made with Primeblue, a high-performance recycled material.
Last updated at 03/10/2026 01:25:51
adidas UltraBoost 21 'Sonic Ink Screaming Green' S23873 US 9½
Delivery $63
originally posted on roadrunnersports.com
A good new version of the Boost! Can definitely feel the extra Boost while being a bit stiffer! Not a carbon plate stiffness BUT solid. Use this shoe for everyday miles. Then buy a carbon plate shoe for speed or tempo runs. Much better wear on tread then the old continental rubber. Solid shoe for 50+ miles per week
originally posted on roadrunnersports.com
It has been over a decade since a last ran on Adidas cause I always found their fit too narrow. I tried the UB 21 and surprisingly it fit me well. The Prime Blue material is top notch and good quality and stretchy. One of the draws to me for trying this shoe was aesthetics and in my opinion the best looking running shoe out right now. However, when running on it it was a different story. I had considerable heel slip more on my right than left heel. I felt the weight of the shoe when picking up the pace to my normal zone 2 pace and when picking it up to marathon and tempo pace the boost cushioning feels flat and dead. The bounce goes away and I didn't feel any responsiveness or pop from the plate on the bottom. It actually felt the opposite like I was fighting the ... MoreIt has been over a decade since a last ran on Adidas cause I always found their fit too narrow. I tried the UB 21 and surprisingly it fit me well. The Prime Blue material is top notch and good quality and stretchy. One of the draws to me for trying this shoe was aesthetics and in my opinion the best looking running shoe out right now. However, when running on it it was a different story. I had considerable heel slip more on my right than left heel. I felt the weight of the shoe when picking up the pace to my normal zone 2 pace and when picking it up to marathon and tempo pace the boost cushioning feels flat and dead. The bounce goes away and I didn't feel any responsiveness or pop from the plate on the bottom. It actually felt the opposite like I was fighting the shoe just to get a quicker turnover. It also felt clunky. When at jogging pace the shoes felt fine and could feel the boost cushioning. Overall not the cushioned daily trainer I expected and this version has leaned more towards the casual athleisure category. This is a great walker/jogger but as a shoe part of a rotation for training it's a hard pass. Really wanted to like this shoe but for what I bought it for it's a big disappointment and will be returning it.
originally posted on finishline.com
I really liked the Ultraboost 20s and bought 2 pairs of the Ultraboost 21 to add in my rotation. I work out 4-5 days a week, doing cardio and weights. And these feel really good on my feet. I am not an avid runner, but as advertised, the additional boost feels more responsive and more cushioned. If you liked the Ultraboost 20s, you'll like the upgrade on the Ultraboost 21s. I am a heavy set guy, I've lost over 60 lbs in the last year, and have put my Ultraboosts through the test...
| Colorway | u4e01u9999Purple |
| Sole Material | Rubber Sole |
| Toe Type | Round Toe |
| Heel Type | Flat heel |
| Closure | Lacing |
adidas UltraBoost 21 'Sonic Ink Screaming Green' S23873 US 9½
Delivery $63
A good new version of the Boost! Can definitely feel the extra Boost while being a bit stiffer! Not a carbon plate stiffness BUT solid. Use this shoe for everyday miles. Then buy a carbon plate shoe for speed or tempo runs. Much better wear on tread then the old continental rubber. Solid shoe for 50+ miles per week
It has been over a decade since a last ran on Adidas cause I always found their fit too narrow. I tried the UB 21 and surprisingly it fit me well. The Prime Blue material is top notch and good quality and stretchy. One of the draws to me for trying this shoe was aesthetics and in my opinion the best looking running shoe out right now. However, when running on it it was a different story. I had considerable heel slip more on my right than left heel. I felt the weight of the shoe when picking up the pace to my normal zone 2 pace and when picking it up to marathon and tempo pace the boost cushioning feels flat and dead. The bounce goes away and I didn't feel any responsiveness or pop from the plate on the bottom. It actually felt the opposite like I was fighting the ... MoreIt has been over a decade since a last ran on Adidas cause I always found their fit too narrow. I tried the UB 21 and surprisingly it fit me well. The Prime Blue material is top notch and good quality and stretchy. One of the draws to me for trying this shoe was aesthetics and in my opinion the best looking running shoe out right now. However, when running on it it was a different story. I had considerable heel slip more on my right than left heel. I felt the weight of the shoe when picking up the pace to my normal zone 2 pace and when picking it up to marathon and tempo pace the boost cushioning feels flat and dead. The bounce goes away and I didn't feel any responsiveness or pop from the plate on the bottom. It actually felt the opposite like I was fighting the shoe just to get a quicker turnover. It also felt clunky. When at jogging pace the shoes felt fine and could feel the boost cushioning. Overall not the cushioned daily trainer I expected and this version has leaned more towards the casual athleisure category. This is a great walker/jogger but as a shoe part of a rotation for training it's a hard pass. Really wanted to like this shoe but for what I bought it for it's a big disappointment and will be returning it.
I really liked the Ultraboost 20s and bought 2 pairs of the Ultraboost 21 to add in my rotation. I work out 4-5 days a week, doing cardio and weights. And these feel really good on my feet. I am not an avid runner, but as advertised, the additional boost feels more responsive and more cushioned. If you liked the Ultraboost 20s, you'll like the upgrade on the Ultraboost 21s. I am a heavy set guy, I've lost over 60 lbs in the last year, and have put my Ultraboosts through the test...
I run from 1 to 1.5 hours daily and have for about 50 years. I buy two pairs of shoes at a time, rotate them daily, and replace them with another pair in about three months. I have worn Adidas exclusively for about 30 years. The Ultra Boost 21 is the most uncomfortable Adidas shoe I have worn. I blame the thick plastic "plates" housing the eyelets through which the shoelaces run. With little effort, the edges of the plates could be filed to a knife's blade sharpness. They are that thick. They are so thick that they inflexible, probably by design. And, other than hold the eyelets for the shoelaces, their only function seems to be to cause the upper parts of my feet to hurt. These shoes are miserable to wear. I am stubborn, so I am going to wear them for three months. ... MoreI run from 1 to 1.5 hours daily and have for about 50 years. I buy two pairs of shoes at a time, rotate them daily, and replace them with another pair in about three months. I have worn Adidas exclusively for about 30 years. The Ultra Boost 21 is the most uncomfortable Adidas shoe I have worn. I blame the thick plastic "plates" housing the eyelets through which the shoelaces run. With little effort, the edges of the plates could be filed to a knife's blade sharpness. They are that thick. They are so thick that they inflexible, probably by design. And, other than hold the eyelets for the shoelaces, their only function seems to be to cause the upper parts of my feet to hurt. These shoes are miserable to wear. I am stubborn, so I am going to wear them for three months. I will then use the plastic plates to scrape paint off walls. I gave the shoe two stars because everything but the plastic plates is okay. I do not recommend this shoe.
I purchased the 21 Boost based on previous experience with the 20's. While these are very different in looks, they provide the same comfort. I'm not a runner, but the cushion in these really help alleviate back pain during long time use. The color way is amazing, I'm a fan of the small details in the upper of the shoe with small touches of the accent color throughout. If you're looking to buy a pair but find yourself on the fence, make the jump. Your feet and back will thank you and you'll get plenty of compliments as an added bonus.
Not sure if others will experience this: I want to like these shoes. I kept telling myself I did like them, and that I just needed to break them in. I've going on multiple walks, and two runs, and the shoes are too uncomfortable to wear. I think they are too tight around the middle of the foot, but I can't explain why they hurt so much. They just make the middle of my feet ache intensely during walks/runs.
All out red looks exteemely sharp! The extended boost sole looks sharp and provides additional stability. Upper is well made with very little evidence of stich/glue lines. Can wear casually or for running but sole is not flat or firm enough for most gym leg-day exercises. We ordered a full size down as the shoe runs noticably large.
I've had the last three versions of this shoe including an ST version back in the day and this shoe continues to impress. I do a lot of hill work and the new toe plate has been great working through my transitions. I'm normally a size 13 but I always size up for the extra toe box room and this one continued with that trend. The toe plate makes the shoe a tad firmer on the ball of the foot but the performance is still there and it's my new daily work horse. I'm 6'1" and 220lb and this shoe definitely gets the job done.
I'm a fan of ultra boost tech, have had every model and decided to buy this one on sale. When it first arrived I was super excited to try them on. Out the box, my first impression was that it seemed to follow previous models and was made from solid materials, once on foot my feelings changed. Super comfortable, light weight but LONG. Mens size 8 looked more like a 10. The silhouette was more like a clown shoe paired with a huge heel and I just couldn't keep them.
I'm a recreational runner, some trail and some road. I very much enjoyed the UB 19's and decided to skip a version and go fro the 21. The magic is still there in the springy, comfy road feel and still good to go on hardback trail. The change in the upper Wass the downfall and the reason for 3 stars instead 5, the toe box is not as roomy and really punished my big toes. If you can wear the Nike Peg 37 without issue, this will likely be ok for you. I am also a big fan of the Peg, but similarly the latest version is to tight on the big toe for me. Have great run, there is never a bad one.
| Colorway | u4e01u9999Purple |
| Sole Material | Rubber Sole |
| Toe Type | Round Toe |
| Heel Type | Flat heel |
| Closure | Lacing |
