Article by Jeff Beck, Steve Gedwill and Sam Winebaum
Ultraboost Light ($190)
Introduction
Sam: I am going to go out on a limb and say the Ultraboost Light is the most significant new and effectively executed trainer from adidas for the “average runner” in many years. At least for me and since the 2013 Energy Boost 1 and if lighter duty, earlier Boston as adidas daily trainers got progressively heavier, less inspiring to run and clunky.
Yes, we have a fleet of adizero line trainers such as the Energy-roded Boston 11, and the wild Prime X Strung. And for sure the budget Supernova 2 was a huge pleasant surprise but both were on the fringes as mainstream trainers for the more serious recreational runner with the Boston 10/11 more faster to elite runner focused.
Now with the Ultraboost Light, adidas, without messing with the iconic looks and thus sales potential to non runners of its huge Ultraboost franchise, manages to bring the model way forward in run utility with a dramatic drop in weight and other improvements.
Resembling prior Ultraboost, that is for sure, it loses a massive 2 oz / 57g in my US8.5 in large part due to the use of a new Light Boost expanded bead TPU compound.
With a weight of 10.3 oz / 292g in my size US 8.5, it is still not “light” as trainers go or as highly stacked at relatively low 30mm heel / 20mm forefoot on a broad platform. but it is for sure now in the hunt as a daily trainer and not just a style shoe that can run a bit.
The upper is still Primeknit with over 50% recycled content and we still have the now iconic TPU cage in a new and lighter configuration,
Underfoot we see a new more “linear” Linear Energy Push system of TPU plate and outsole.
Let’s see how they perform!
Pros:
Gigantic 2 oz / 57g drop in weight now makes the Ultraboost a true running shoe: Sam/Jeff/Steve
Boost Light foam is delightful in its cushion and quick (quicker than Boost) rebound: Sam/Jeff
Agile LEP plate delivers plate like response, and has the trademark quick Adi front flex: Sam
Stable, broad (but not bulky or back weighted with foot sitting down in the foam and with a clip) rebounding quick transitioning heel, great for heel strikers and downhills Sam/Jeff/Steve
Never felt the rear plastic clip, a truly marvelous thing and it clearly helps stabilize: Sam/Jeff
Forgot about it upper: smooth secure fit for a variety of foot shapes (stretch knit and cage): Sam/Jeff/Steve
Stable and secure enough even for those with light pronation control needs: Sam/Jeff/Steve
10% reduction in overall carbon footprint of shoe, process, packaging. Sam/Jeff/Steve
Toebox width is ample. Jeff
Cons:
Cage and knit adds to weight but after all this is an Ultraboost Sam
A bit thin in feel at the forefoot in feel: low stack and LEP plate Sam/Jeff/Steve
Pricing at $190 and especially as it is not sub 10 oz with relatively low stack height Sam/Jeff/Steve
Stats
Estimated weight: men's 10.55 oz / 299g (US9)
Samples: men’s 10.3 oz / 292g US8.5, 11.32 oz / 321g US10.5
(2.7 oz / 76g lighter than UB21 in US 10.5)
Stack Height: men’s 30 mm heel (measured) / 20 mm forefoot ( 10mm drop spec)
Available now including at our partner Running Warehouse HERE. $190
First Impressions, Fit and Upper
Sam: The Primeknit upper is made of at least 50% recycled content. The infamous plastic “cage” is now more flexible as is the rear clip which extends down (and hidden) behind the heel foam to provide flexible support.
The rear side of achilles bolsters and padding of the rising achilles collar are prominent and moderately soft with great lockdown and comfort.
The achilles area at the far back is cradled between the rear clip which serves as a moderately pliable heel counter.
I never noticed its forward extension interfering with my stride flow as some such clips do (Nike Infinity Run, Brooks Guide Rails).
The fit is for sure true to size with a broad and low toe soft knit box which unlike most prior UB, never pressed down on my toes.
Given the stretch of the knit and the ability of the cage to adapt when laced, I think a wide range of foot shapes will be accommodated here.
Jeff: At first glimpse, you could easily confuse this for a slightly different colorway of previous Ultraboost models. The changes are subtle visually, but once on your foot, there’s no mistaking this is a big step forward. While it’s not a super lightweight shoe, it tips the scale 2.7 oz/76g lighter than my pair of Ultraboost 21 in a US10.5, and that kind of weight drop is dramatic.
The upper is fantastic, holding the foot well but all but disappearing on the foot. Even though it is a knit with some stretch, it swaddles the foot very well.
Sam is correct, the heel clip is effectively non-existent if you don’t need support. The early versions of Ultra oost had a cage that was, as politely as I can put it, was “intrusive" around the midfoot.
While there’s still a cage, I think it’s actually kind of great. The knit upper is so pliable that without the cage I think it would have been a bit of an unstructured mess.
It fits true-to-size lengthwise, and my slightly-wider-than-normal foot fits fine as well. The stretch of the upper can accommodate the foot width without issue.
I agree with Sam, the toebox is a little low, but as there’s enough vertical stretch, it isn’t a problem. That same stretch allows the toebox to act even wider than it is - there’s solid toe splay space.
Steve: Right out of the box it looks like that classic Ultraboost design, but under the hood (midsole) we have the major update. Adidas turbocharged this new Light Boost TPU compound, which increases energy return in a much lighter package. At step in, I knew right away that the upper was going to be very secure. No need for adjustments here, just lace them up and head out the door. The knit upper provides a snug feeling fit, I agree with Sam and Jeff that the volume is low at the front of the toebox. The low volume makes it feel like the shoe runs short, but it fits true-to-size with no rubbing issues. The signature midsole cage and heel counter provides excellent lockdown. Overall it's a very comfortable and stable shoe!
Midsole
Sam: 30 % lighter LIght Boost expanded pellets TPU foam leads in large part to an Ultraboost weighing 2 oz / 57g lighter than UB21 in my US 8.5. And that is the key story for this new edition.
We come in at about10.5 oz / 298g in a US9 so while a remarkable drop also maybe an indication that the foam is not a supercritical foam which given the stack height one would expect have led to a lighter yet shoe.
I measure a total stack height of 30mm heel with a 20 mm forefoot (10mm drop spec) so it is relatively heavy compared to many current max stack height shoes training and racing shoes, including adidas own Prime X Strung but it sits on a very broad and stable platform.
The foam itself is still an expanded TPU pellet compound. We do not as of yet have confirmation if it is supercritical processed as of yet or not.
The midsole foam is less squishy and more quickly rebounding (helped by the plate and outsole) than earlier Boost shoes and certainly does not require an EVA layer as some Boost midsole shoes do to keep things stable. Adidas tells us the new Light Boost here is slightly denser and that is what I feel.
We have a broad platform with the foot sitting down in the rear midsole sidewalls (the top of the sockliner is at the top of the “Light Boost” lettering on the midsole above), a well executed not in my way and reduced in side height plastic clip at the rear extending down for flexible support, the plastic upper cage which is now thinner and more flexible and the LEP plate and outsole.
Ultraboost 21: Note higher yellow side rails
This “neutral” shoe is plenty stable. It is one rare shoe that I think should accommodate both neutral and more heavily pronating runners just fine.
The new geometry with foot sitting down far at the heel in the broad rear midsole delivers very stable highly cushioned rebounding heel landings while the deep decoupling groove keeping the flow forward easy at any pace. I am also frankly surprised how well the extended clip works compared to Nike’s and Brooks far more noticed and in the way implementations
and wouldn’t have even guessed it was there.
The bottom loaded LEP plate (and outsole) not only deliver a stable toe off with clear energetic and snappy impulse from the plate but it has that characteristic Adi front flex point. The plate is clearly flexible and not rigid as Energy Rods shoes such as the Boston 11 and has a flex feel more similar to Saucony’s Endorphin Speed 3’s.
Compared to the UB 21 shown above, the LEP is now no longer bridged at mid foot, a la old school Torsion plates but is now connected at the very front, the center rubber coverage is slimmed down, the outer front black Continental extended further back .
Along with less extensive outsole coverage at the heel, a deeper decoupling groove, and less rubber upfront (all weight reducing) adidas set out to accentuate roll through for all strike types and I think succeeds.
The geometry combines both plate impulse and flexible toe off, something I like a lot in both trainers and racers. Mind you, in part, and maybe in large part, this occurs because we have a total of not much more than 20mm of forefoot total stack, very thin by today’s standards which often approach or exceed 30mm. Thus, forefoot strikers may find the front of the shoe firm. I tend to heel strike in training and while I did indeed find it thinner than many, the Boost’s rebound, the plate, outsole, and front flex had me smiling.
Jeff: How do you follow that up? Sam does a great job addressing the midsole of the shoe. It’s a bit deceptive, because it looks so massive but as Sam pointed out, it's far from a maximal shoe.
The lion’s share of the cushioning is in the heel, so as a midfoot striker I miss out on most of it. The forefoot definitely feels thin, especially as running shoes have gotten simultaneously more cushioned and especially up front and lighter weight.
Especially when you consider the (still relatively heavy) weight of the shoe, the forefoot stack really should have the 30mm of stack that the heel has, and the heel should be approaching 40mm. Obviously that would make my 11+ oz 10.5 even heavier - but check the stats of the Saucony Triumph 20 and tell me it’s not possible.
But that’s been my complaint from the start of the Ultraboost line in 2015 as it leaves the shoe in a murky spot when it comes to establishing a clear role for your average runner. While the forefoot stack has grown slightly from the initial 17mm, 20mm in 2023 pales in comparison - no one is going to call the Saucony Ride an ultra-cushioned shoe, and it’s has 7mm higher stack in the forefoot.
Steve: Sam is coming in hot! He just dropped that knowledge on us all! I agree with Sam and Jeff here, you would think this is a max stack shoe, but 20mm/30mm is pretty conservative to today's standards. Take into consideration for example that the Nike Pegasus Turbo 2 is 18mm/28mm. The forefoot does feel a bit thin as Jeff stated, and as a midsole striker as well, I definitely noticed this.
Outsole
Sam: The outsole has “Natural” Continental rubber. We asked but Adidas wasn’t very precise as to what the natural part was beyond it being made in part from “natural resources.” There are 4 types of rubber here: rear firm gray, mid shoe "crystal" type rubber, a soft center insert and burly firm outer front Continental
Compared to the UB22 shown above the rubber coverage while still extensive is more judicious and more purposeful to the platform and run flow.
The rear coverage is reduced as we now have that super effective landing pad and decoupling groove. Despite the firmness and depth it did not lead to an overly firm landing feel at the road, so it is well matched to the midsole and very stabilizing.
Crystal type rubber extends forward from the midfoot all the way to the front with upfront 2 strips of firm thick Continental rubber for wear and to stabilize the toe off. Down the center front we have a softer rubber.
Grip is fine and durability should be excellent but what adidas has really done here is match the outsole to the midsole feel and rest of the geometry of Boost Light midsole and LEP plate very well to get a somewhat flexible noticeably rolling motion forward through the gait cycle
Jeff: The three-in-one rubber combination may be the first I’ve experienced that much variation. I agree, the very firm heel rubber is incredibly durable without making the shoe dull - though I’ve found the other two rubber types to have great durability as well. The Continental rubber is always among the best out there, but this version of crystal rubber has great traction; I’ve found most crystal rubber is underwhelming in that department.
The one gripe I have about the outsole is minor: it holds onto tiny rocks and stones like few other shoes do. Each shoe has about two dozen tiny rocks jammed into the gaps in the rubber. I haven’t taken them on any trails, that’s just coming from running on roads. It’s not a big deal to pick them out if you are so inclined to clean them out, just found it interesting that it’s that much of a rock magnet.
Steve: Not a ton to add here, the Continental rubber has excellent grip and will hold up quite well. I just wonder if there was another opportunity to save weight here.
Ride
Sam: Adidas finally not only delivers a totally runable Ultraboost (much lighter weight, improved Boost and overall underfoot geometry), but their first real more mainstream daily training shoe in a long long time and quite frankly since Energy Boost 1 for me.
Not a light ride as we are at 10.5 oz but a dynamic one with plenty of rebounding heel cushion and stability and a lively quick if thin toe off feel helped for sure by the big 10mm drop. I do wish for a bit more forefoot cushion but, even if thin, the front Light Boost layer is enough for me for up to moderately long runs. It has a pretty much deal easy to flow training ride for me as a heel striker at slower paces as, unlike other broad platform shoes, the heel is not in the way, the transitions easy with a final bottom loaded, rapid plated toe off feel at faster paces.
Jeff: This shoe really benefits a heel strike, with the 30mm heel soaking up the impact much better than the forefoot. I’d agree, this is a much more runnable shoe than the previous Ultraboost shoes have been, and very similar to the adidas Solar Glide I reviewed a few years ago.
The plate doesn’t turn it into a super shoe by any stretch, but the subtle rocker works well. And you can imagine if Sam would like more forefoot cushioning, a much heavier midfoot striker like myself would absolutely love it with more up front. The lack of front cushioning really paints it into a best-use for casual wear corner - which is where the UB line has been since launch.
Steve: With the weight and thinner forefoot, my fore to midfoot landing had an audible thud, not super supportive and my turnover didn't feel naturally easy. I do however feel the midsole provides an adequate amount of cushion and responsiveness for moderate distances. I experimented with my landing, and I can confirm it feels very cushioned for a heel strike. The transition through the gait also felt smoother with the heel strike. It's quite stable and the glove-like fit up the upper is very secure and feels great on the run.
Conclusions and Recommendations
Jeff: Boost as a midsole material receives a long overdue update, but ultimately I found midsole proportions lacking with not nearly enough cushioning underneath the forefoot. The outsole is a marvel of synergy, and it has one of the best knit uppers ever made.
But the thin forefoot limits its versatility, and while it has dropped a lot of weight, my US 10.5 is still over 11 oz. That weight alone usually points at a well-cushioned easy trainer, but by the time any of my runs went over an hour, the balls of both feet were ready to be done. Overall the shoe is a bit of a miss for me, but I’m enthused for what else adidas will do with this much lighter midsole, hopefully with a bit more underfoot.
Jeff’s Score 7.35/10
Ride: 6 (50%) Fit: 10 (30%) Value: 6 (15%) Style: 9 (5%)
😊😊
Steve: The Adidas Ultraboost Light is a massive improvement and is close to breaking out of that casual running category. Some added Boost upfront and some weight saving options could really turbocharge this shoe. The thinner forefoot and heavier weight does shift this shoe to my casual pile. There are just too many offerings with more cushioning and lighter weight to be in my rotation. I took them with me on my recent trip to Florida and wore them daily, they are stylish and super comfy. I think the Boost Light falls just short of a legitimate daily trainer.
Steve's Score: 7.25/10
Ride: (6) Style: (9) Value: (7) Fit: (9.5) only lost points on fit due to the low front toebox volume.
😊😊😊
Sam: adidas dramatically updates the run ability of the Ultraboost, one of the pillars of its overall business, without changing its essence or iconic style. Not easy to do! While not that “light” for its relatively modest stack height for modern trainers, it is no longer a ponderous to run shoe that was more about lifestyle than actual run training for me, and I suspect many others as well as it loses 2 oz of weight on the same broad platform.
By re-imagining Boost and making it 30% lighter and somewhat denser and springier, adidas has delivered a foam that closes a big gap in their run line between the firm Lightstrike foams and more budget Bounce. Boost Light has a lot of potential for not only road but trail as later this year adidas Terrex will have an ultra type shoe with Light Boost on board.
Finally, adidas also delivers an Ultraboost Primeknit upper and associated rear clip along with cage and support system that is without reproach in terms of fit and hold and is beautifully integrated, supportive, and comfortable.
The ride is now much more up my alley: a broad stable rebounding heel landing, easy transitions and a thinner snappier toe off with flex. The rear landing geometry, LEP and outsole are both very well implemented and brought together to provide a lively in no way ponderous experience that suits all my paces (if not my longest distances), reminding me up front of the quick turning over adizero of the past. It runs lighter than the not exactly light shoe weight and at a weight dramatically lower than prior Ultraboost all of which is totally felt.
Bottom line: The Ultraboost Light is a successful functional update to an iconic style that, while it was called a “Running Shoe '' really wasn’t ever for me due to its weight and often shaky upper. The Light retains the UB style and vibe that so many love. I score it in part for what it is, a solid and careful update to what is a key key element of adidas overall business.
It now, at long last, becomes a fine, decently light and quite versatile run trainer. It starts to plug a hole for such shoes in the adidas line on the more mellow side that only the Supernova 2 was able to deliver in their lines in recent times for me. I wish it was lighter yet and had more front cushion to extend its range but this likely will come with new models with Boost Light midsoles, lighter uppers and different underfoot geometries.
Sam’s Score: 9.17 / 10
Ride: 9.1 (50%) Fit: 9.4 (30%) Value: 8.8 (15%) Style: 9.5 (5%)
😊😊😊 1/2
Please Watch Sam's Ultraboost Light Video Review (11:17)
8 Comparisons
Index to all RTR reviews: HERE
adidas Ultraboost 21 (RTR Review)
Jeff: Visually they could nearly be the same shoe, the UB21’s behemoth weight overshadowed all of its other performance issues. But with a new midsole and a few other minor changes, the Boost Light dropped a ton of weight and improved the geometry a great deal - no more horse hoof “clop clop” while I’m running, unlike the UB21. While I’m still underwhelmed by the forefoot cushioning, the Boost Light is a massive step up from the Ultraboost 21.
Steve: I could maybe see why a heel striker would select the Ultraboost over the Nimbus 25. It's just not an argument you're going to win with me. The Nimbus is lighter, has that Cadillac like upper comfort and is much softer underfoot. I'm picking up the Nimbus for easy and long runs 10/10 times.
adidas Supernova 2 (RTR Review)
Sam: The budget $100 Supernova was a huge 2022 surprise for me. With a Boost heel and Bounce forefoot, it punches way above its price. It does not have the distinct snappy front impulse of the UB but is more cushioned and softer in feel up front. Lighter than the UB Light with a similar fitting upper, it is a strong alternative to the UB Light for mellow paced training if budget is a consideration.
Adizero Boston 10/11 (RTR Review)
Sam: The Boston is the adidas more performance oriented “daily trainer”. It underwent huge changes with the 10 going from a Boost and EVA trainer with the traditional Torsion plastic to a stiffer energy roded plated higher stack lighter trainer. It has a 39/31 stack height and weighed a bit less than 10 oz in a US9 in the Boston 10 vs 10.5 oz for our Ultraboost Light with its lower 30/20 stack height. It sits, if you will at another extreme from the Ultraboost with a quite aggressive ride I find more suited to the faster runner and my faster days while the Ultraboost sits as a more mellow, if thin forefoot, near daily trainer. Work to be done by adidas to deliver a daily trainer “between" these two.
Saucony Endorphin Shift 1 or 2 (RTR Review)
Jeff: Saucony’s geometry first daily trainer uses their lower end, and firmer, midsole material PWRRUN (and a ton of it, with a 34mm/38mm forefoot/heel stack that’s 14mm/8mm taller than the Boost Light) with a very aggressive rocker. The firm ride isn’t as fun as Saucony’s more premium trainer, Triumph 20, but it works incredibly well and is much more stable than it should be. The Boost Light geometry is similar, but much more subtle, and ultimately the difference in midsole height overshadows everything else.
ASICS GEL-Nimbus 25 (RTR Review)
Jeff: ASICS went all out with the upgrades when they released the Nimbus 25, with one of the most comfortable midsoles paired with an extremely plush upper and 13.5mm higher stack under the forefoot and 11.5mm more under the heel - and yet it still comes through almost a half ounce lighter than the Boost Light. The Nimbus cleanly slots in as a daily trainer for runners who like more cushioning, or at very least as your easy day shoe, the Boost Light wouldn’t be my pick for either of those roles.
Sam: Jeff has the stats right. I personally prefer the snappier (if thin in cushion) front roll of the Ultraboost here, at least for up to moderate distances and find it has a more than adequately cushioned heel and more dynamic rebounding one that as a heel striker at slower paces I can transition off of easier than the blocky over stabilized Nimbus 25’s.
Nike ZoomX Invincible Run 3 (RTR Review)
Sam: Nike's max cushion trainer weighs a bit less and has a considerably higher stack height with ZoomX foam clearly having a weight advantage over Light Boost and a somewhat springier feel. Underfoot, the heel cushion ends up about same with upfront the Nike having considerably more cushion but with far less of a snappy toe off relying on a somewhat awkward rocker. Far more stable than prior Invincible, I see it as a long slower run and daily training shoe with the Ultraboost Light more suitable for shorter runs. As far as uppers, no contest the UB's for sheer comfort (and wider feet) with the Nike's more performance oriented, maybe a bit o much so for the shoe's purposes. True to size in both for me.Saucony Ride 16 (RTR Review)
Sam: Jeff mentions the 7mm more front stack height up front of the Ride 16. Indeed this much lighter at 8.8 oz daily trainer is a better all around run training shoe than the Ultraboost for me. I would comment (and yes its upper for sure adds to the weight) that the Ride 16 true to size upper is far snugger and more performance oriented and not an upper or shoe I would pick to wear all day, outside or running as I would in a heartbeat the Ultraboost Light.
New Balance FuelCell SC Trainer (RTR Review)
Jeff: New Balance’s massively stacked trainer/super shoe hybrid boasts a softer and bouncier midsole with a more pronounced rocker, and a plate that’s aimed more at performance than stability. The Boost Light has a more stable platform, but considering its forefoot stack is roughly half the height (20mm vs 39mm in the New Balance) that’s not a revelation. The adidas upper is much more form fitting, and while the SC Trainer’s upper isn’t bad, the Light Boost knit is on another level.
Steve: As soon as I received the Adidas Ultraboost Light, I knew what beer I had to find! It's actually perfect timing since Mardi Gras was this past week!
Abita Brewing Company was founded in 1986 and is located 30 miles North of New Orleans. Abita produces more than 125,000 barrels of beer, and is still privately owned and operated by local shareholders.
Pretty easy match up here, what does a Turbo produce? That's right, Boost!
Turbo Dog is a Brown Ale that has aromas of roasty malts, and caramel. It is medium bodied, tasting notes of chocolate, light roast coffee, and some caramel sweetness. Finishes pretty dry, a nice little brown ale!
3.5/5 beer mug rating 🍺 🍺 🍺 1/2
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Jeff Beck is the token slow runner of the RTR lineup, and as such his viewpoints on shoe and gear can differ from those who routinely finish marathons in three hours or less. Jeff runs 20 miles per week on roads and trails around Denver, CO (and sometimes on the treadmill when the weather gets too much for a Phoenix native). Jeff only got into running in his 30s, as a result his career PR's are 4:07 for the marathon and 5K at 23:39. Jeff has finished several ultra marathons, from 50K up to 50 miles, and is still debating if he wants to go down that road again.
Steve: A former high school track runner, turned physique competitor who then jumped back into the running scene. Currently running 20-30 miles per week, my most recent race times are 36:07 for 8k and 47:12 10k. I am 6’0 175lbs and in my mid 30’s. I am a husband, dog dad, craft beer enthusiast and a big time shoe geek!
Sam is the Editor and Founder of Road Trail Run. He is 65 with a 2018 3:40 Boston qualifier. 2022 was Sam’s 50th year of running. He has a decades old 2:28 marathon PR. These days he runs halves in the just sub 1:40 range, if he is very lucky, training 30-40 miles per week mostly at moderate paces on the roads and trails of New Hampshire and Utah be it on the run or nordic skis. He is 5’9” tall and weighs about 164 lbs, if he is not enjoying too many fine New England IPA’s.
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