Adidas Adizero Boston 12: The Real Successor the Boston 9?
By Matt Klein, Nathan Brown, & David Salas
The Boston series underwent a huge overhaul for version 10, which brought the line from a lower, lightweight trainer and racing shoe (for its time) and turned it into a higher stacked, stiff, and rockered shoe. Given the major shift, many former Boston lovers were turned away, while others found a liking in a trainer from Adidas that had an overall firmer and rockered ride. For our team, the 10th version became one of our main trainers for long runs and snagging high mileage. However, version 11's upper missed the mark in a major way with a few upper issues. Despite our enjoyment of version 10, there were still many things to be improved upon, as the shoe took a long time to break in and was just a bit too firm. Enter version 12, another major revamp to the Boston line, which feels like a much more natural progression from version 9.
Adidas Adizero Boston 12Price: $159.95 at Running Warehouse
Weight: 9.4 oz, 267 g (men's size 9), 8.0 oz, 227 g (women's size 8)
Stack Height: 37 mm / 30.5 mm
Drop: 6.5 mm
Classification: Performance/Uptempo Trainer
RUNNING SHOE SUMMARY
Matt: The Adidas Boston 12 is a performance trainer for training and workouts. The newest version features a larger amount of Lightstrike Pro, especially in the forefoot and a large slab of Lightstrike 2.0 in the heel. This provides a softer and bouncier ride that lends itself well to uptempo training and workouts. A new upper provides more room and requires locking the laces down to get a secure fit. Those disappointed with versions 10 and 11 will find that the Boston 12 makes its way back toward the performance level of version 9. Good enough for daily training while featuring enough bounce and speed to handle some serious workouts.
Nathan: The Boston 12 is a higher-stacked shoe with a dual-density midsole and energy rods to stiffen the sole a bit. It has a healthy amount of Lightstrike Pro in the forefoot which gives a slightly softer feel for toe-off, and is more flexible in the forefoot than its predecessor due to the alteration of the rod stiffness. It is now a neutral trainer that is light enough to get a bit of faster work in, but still is best for daily miles.
David: The Boston 12 is a performance trainer aimed to be the training companion to your race day shoe. The Boston uses a dual density midsole consisting of full length Lightstrike 2.0 and a thick piece of Lightstrike Pro midsole found in their racing models in the forefoot. They also use a stiffening agent with the Energy Rods 2.0. The shoe really shines at faster paces and is a true workout companion. It can run easy as well, though serves best as a training companion. This will be your versatile "one shoe" if you need to warm up, rip a workout, and cool down in the same shoe or have a long run monster.
SIMILAR SHOES: Puma Deviate Nitro 2, Nike Zoom Fly 5
PAST MODEL: Adizero Boston 11
FIT
Matt: The Adidas Adizero Boston 12 fits me true to size in my normal men's US size 10. The volume is a little lower with more width in the forefoot than prior versions. The overlays have been removed and a light, flexible toe guard sits in its place. The upper is en engineered mesh that provides some mild stretch. This provides a surprisingly accommodating fit in the forefoot. This transitions to a normal fitting midfoot. The tongue is thin, ungusseted, and free-floating. There is internal reinforcements in the midfoot that come up to interact with the laces (grey pieces). I had to really tighten down the laces to get security in the midfoot and found these pieces clunky and in the way of getting a good lockdown. The security is fine running in a straight line, but was not as good with any turning. A smooth insole inside the shoe contributes to this and any lateral motion made my foot slide in the midfoot.
The rearfoot features a thin, smaller flexible heel counter. There are small portions of heel collar cushioning at the top of the heel but the remainder of the upper at the rearfoot is thin. The counter was thin enough that I had no issues with it and only those extremely sensitive to counters will have trouble. Despite the midfoot slippage with lateral movement, I did not experience any heel slippage. However, due to the internal movement with any turning I would highly suggest using socks with this. Additionally, the inner mesh is a little scratchy, which is not a problem with appropriate socks. Outside of that, this is a decent performance upper.
Nathan: I wish I didn't have to start with fit, because it may paint the shoe in a bad light. Overall the fit is true to size, but it lacks the comfort and function that I would want in a training shoe. They utilize a thinner, synthetic-feeling upper material that thankfully stretched out a bit because at first, the toe box was low volume. The heel has a heel counter but very minimal padding, which did irritate my heel on longer efforts. Part of this is that lockdown was only okay in the heel, likely due to the lack of padding to grip the heel. Midfoot lockdown, on the other hand, was good and secure. The other odd part for me was the lacing system. It felt unnecessary and was difficult to adjust.
The one positive of it is that once you had it in place, it did not change and wouldn't need an adjustment on subsequent lacing. The pros of this upper were the midfoot security and lighter nature to keep all the weight down. The downfalls were in heel security, comfort, and lower volume in the toe box.
David: The Adidas Adizero Boston 12 fits true to size in my Men's 9.5. The fit and feel throughout is certainly driven towards performance. The synthetic mesh upper has little stretch to it, but locks down well throughout. The fit in the heel is snug/narrow, midfoot is normal to slightly narrow, and forefoot normal to slightly wide. The volume is moderate and does allow for some swelling accommodation during long efforts. The heel collar does not have much padding to it so to those sensitive to heel counters may find some irritation. For me this actually locked the heel quite well and I enjoyed it. The one thing I noticed (and in nearly all Adizero models) is the lateral midfoot has some compression. I think it is from the upper and sidewall integration. The Adios Pro 3 had a similar design that really did not work for me in that lateral midfoot region, though it isn't bothersome enough to deter me on the Boston 12. The tongue is thin but padded just enough to lock it down pretty well without irritation. The Boston 12 definitely feels like it is in the Adizero lineup with the dialed in fit.
PERFORMANCE
Matt: The Adidas Adizero Boston 12 is a performance trainer for daily training and workouts. The sole features a larger amount of Lightstrike Pro in the forefoot and updated Lightstrike 2.0 underfoot. This provides a softer ride underfoot with an especially bouncy ride in the forefoot. The weight is down to 9.4 oz, although it feels lighter than this. There is also a 6.5 mm drop, which feels a little lower thanks to the softer midsole. The large posterior-lateral heel bevel is still present, which provides a smooth transition at heel strike. The full-length rods now feature an additional lateral extension, which either drives the midfoot medially if coming from a heel strike or acts as a stabilizer for those who land at the lateral midfoot. This transitions into the bouncy and surprisingly smooth forefoot. Despite the rods, there is some mild flexibility to the forefoot. Combined with a large forefoot rocker, there is an easy, moderately snappy ride off the front.
Use-wise, the Adizero Boston 12 works best for uptempo work and workouts. The bouncy forefoot works extremely well for picking up the pace and the overall ride transitions quickly. I have used this shoe for a tempo run and intervals. Both ended up being far faster than I expected for a shoe in the 9 oz range. I have been able to do easy miles in this shoe which I have enjoyed because I prefer lightweight trainers and performance trainers for the majority of my mileage. Those who like those types of shoes will find that daily training is fine in this shoe. Most people will find this to be an uptempo shoe that can handle easy, uptempo runs and workouts including tempos and intervals. It is not the fastest or lightest shoe, but makes a great training alternative to lighter or more aggressive shoes like the Takumi Sen or Adios Pro (which should not be used as training shoes).
The durability is excellent like the prior versions. I have 25 miles on my pair and there is no wear on the outsole. This is a road shoe and it does have solid traction on a variety of smooth surfaces. I have used this on mild trails and found it to not be the best option. Rocks do get stuck in the outsole gap, so I would stick to smooth surfaces and instead look to the Terrex line for trail stuff.
Nathan: There are noticeable changes to the feel of the Adizero Boston 12 compared to the 10 or 11. The most noticeable is that it just feels much lighter on foot and in fact is an ounce lighter than version 10. It also is softer in the heel and didn't require a break-in period thanks to the integration of Lightstrike 2.0 and an increased amount of Lightstrike Pro (their midsole material used in their racing models). That said, it still has an overall firmer feel than some of the other models on the market, but I wouldn't call it "firm" anymore. The overall ride still feels rockered, but the forefoot is notably more flexible since they changed the composition of their energy rods. The final difference for me was that despite only being a 1.5mm difference in drop, it felt like a much bigger change than that. This is likely because of the increased softness of Lightstrike 2.0 which compresses more than the original Lightstrike if you land in the heel.
In terms of actual performance, I didn't notice any hitches from heel to forefoot. There is a lateral heel bevel that transitions nicely onto a mild midfoot to forefoot rocker. Again, the ride is overall firmer for me and I didn't really notice the Lightstrike Pro until I started putting in more effort for a tempo or interval run. I preferred running easy and moderate paces in this shoe, but did take it faster than my half marathon pace, which did okay for 2-3 miles. At that point, I could feel the weight and would have wanted something lighter and peppier for longer workouts. The only other issue I had was I could feel pressure under the outside of my left foot where the Energy Rod is extended and exposed. As mentioned before, the drop and foam combination made this feel like a lower drop shoe to me, so I would notice calf fatigue after longer runs as well. However, I expect depending on your mechanics and where you land, this would be a very different feel.
David: The Adidas Boston 12 has been a very fun shoe for me. The shoe is incredibly versatile and can run both fast and slow. It has become a long run monster for me and a solid tempo workout shoe. I was late to the game on this review but I have accumulated around 65 miles on this shoe in less than 2 weeks, as well as two 20 mile efforts.
The shoe transitions quickly and has a lot of liveliness through the forefoot. The heel comes off firmer, as it uses the Lightstrike 2.0 as the midsole. With that said there is still a good amount of cushioning underfoot and I never felt that I was bottoming out or wishing there was more foam. There is a posterior lateral bevel and a slightly decoupled midsole/outsole. The medial heel protrudes a little more than the lateral side having an undercut. This creates the lateral bias and quickly transitioning heel. This shoe really gets you into your midfoot and forefoot quickly. The more forward you transition, the more Lightstrike Pro foam there is. The midfoot and forefoot has a nice bounce and stiffness to it. The Energy Rods have some flexibility to it, though plenty rigid to give some snappiness to the ride. I have found that I really enjoy this shoe for long rhythmic and uptempo efforts. Some specific efforts would include progression runs, fartleks, and long runs.
STABILITY
Matt: The Adidas Adizero Boston 12 is a neutral shoe. The posterior lateral bevel remains like previous versions but the sole in the heel and midfoot have narrowed. This creates a mild lateral bias during heel contact but the foot is almost immediately pitched inward due to the midfoot width and the lateral midfoot extension of the rods. Although this part of the rods was supposed to be visual, it also adds to some medial motion at this area. There are sidewalls, particularly at the medial midfoot. These are made of Lightstrike Pro, which do collapse fairly easily. The softer ride also makes things less inherently stable although the rods partially offset this. The forefoot maintains a stable neutral ride thanks to the width of the sole, the rigidity of the plates and the fact that there is still some forefoot flexibility that facilitates a forward transition. So overall the Adizero Boston 12 moves in a neutral direction away from the stable neutral rides of the prior two versions.
Nathan: The Boston 10 and 11 were pretty solid stable neutral trainers. The Boston 12 I would classify as a true neutral trainer. Part of this is that there is overall increased amount of softness and flexibility, which inherently will increase demand on the runner. Oddly enough, the forefoot of the newest version has a wider forefoot and what seems to be the same width in the heel and midfoot. However, because of the lower drop and softer foam, there feels to be less guidance forward.
The other change is the placement of the cutout. Version 10 and 11 had the cutout closer to the forefoot, but version 12's is right in the midfoot which may lead to increased potential for medial movement.
David: The Adidas Boston 12 is definitely a neutral shoe, though does some things pretty well. The shoe provides great traction and ground feel underfoot despite how much foam there is. The shoe has a moderate base underfoot that helps with cross sectional area. The undercut on the lateral side creates a quick and fun transition into the midfoot, though does increase the pronation speed a tad. For those that struggle with midfoot and forefoot stability it may be a little tough in this model. The upper is very secure throughout and I have found that I can tackle hard turns without too much worry. I have also found that I can run on dirt and grass in this shoe without issue as well. The shoe is certainly neutral, though does have some stability elements.
Thoughts as a DPT: Stiffening Agents and the Path of Least Resistance
By Matthew Klein
After the stiff/firmer rides of the Boston 10 and Boston 11, the Boston 12 is a surprising change. The increase in Lightstrike Pro and the addition of Lightstrike 2.0 have softened the underfoot feel and ride significantly. The increased resilience and compliance of the midsole also allowed for additional flexibility, especially in the forefoot. This is a drastic change from the unbelievably stiff forefoot in versions 10 and 11. David and I have repeatedly discussed, albeit with testimony rather than hard evidence, that running extremely fast seems to be more enjoyable in shoes with a bit of flexibility compared to those that are extremely rigid. The higher rigidity seems to work better over longer efforts where efficiency is key, whereas the mild flexibility seems to help facilitate a forward transition rather than resisting one as some overly stiff shoes can do.
It is for the above reasons that companies need to be cautious with where they put rod or plate extensions to "show off" technology. The lateral projection of the rod in the midfoot may have some functionality to balance out the lateral heel bevel but it will also drive certain people farther medially. People are more likely to go medially due to the foot traveling through the path of least resistance. The forefoot does this well with the rods evenly spread out across the width of the sole. Those that supinate too far at the midfoot may do well here, while those who go a bit too medial may have some trouble. This is not an overt criticism of the shoe but instead, something companies need to be careful with.
Sources:
Hébert-Losier, K., & Pamment, M. (2023). Advancements in running shoe technology and their effects on running economy and performance–a current concepts overview. Sports Biomechanics, 22(3), 335-350.
Ortega, J. A., Healey, L. A., Swinnen, W., & Hoogkamer, W. (2021). Energetics and biomechanics of running footwear with increased longitudinal bending stiffness: A narrative review. Sports Medicine, 51(5), 873-894.
RECOMMENDATIONS
Matt: The Boston 12 is a massive update and improvement over version 11. The transition is smoother, the midsole is bouncier, the ride is more comfortable, the weight is lower and overall the shoe feels faster. My only major suggestions are with the lateral midfoot rod extension and the upper. I realize Adidas wants to show off the rods but that is already done through the outsole cut-out on the bottom of the shoe. The lateral extension creates a bit more medial bias than necessary and I would recommend removing it. The upper fits better than the previous versions but could use more structure in the midfoot. I do not feel that the midfoot has adequate lockdown when moving any direction but forward, so would suggest a gusseted tongue and removing the thick pieces that intertwine with the laces that only add bulk. Outside of that, this is an excellent shoe that I have enjoyed putting mileage on!
Nathan: Most of my recommendations are directed at the upper. Mainly considering increased heel padding, a simplified lacing system, and opening up the toe box could go a long way. Second is moving the cutout slightly toward the forefoot and then removing the lateral extension, which seemed only to cause irritation (at least for me). If there are goals of improving lateral stability, I can understand the extension, but if that isn't the purpose, I would propose to remove it.
David: I really enjoyed my time in the Boston 12. So much that it is entering contention for one of my shoes of the year. The big thing I would like to see adjusted would be the lateral midfoot integration of the heel collar and upper with the sidewalls. I have noticed a similar sensation in the Adios Pro 3 and Adizero SL as well. It is something I notice right away and I'll have a small pressure sensation to the base of my 5th metatarsal. This seems to go away when I start running, though still prevalent.
WHO THIS SHOE IS FOR
Matt: The Adidas Adizero Boston 12 finally brings the Boston series back toward the performance trainer feel of the originals (before 10 and 11). Like versions 5 through 9, it returns to being a training companion to the now Adios Pro that can also handle workouts. Those who like large amounts of Lightstrike Pro will enjoy the feel in the forefoot, while the Lightstrike 2.0 also makes for a softer performance ride in the rear. The upper is a little funky and may need some work but it does a decent job providing some security when moving forward (just don't turn in it). The Continental rubber keeps the durability high, so runners should be able to save miles on their super shoes while still having some that can handle training and workouts. The stability has decreased to a true neutral shoe but the Boston 12 is finally back as an uptempo performance trainer. This was previously missing in the Adizero line but runners wanting a training/workout shoe finally have this one back.
Nathan: The Boston 12 is another big update to the Boston line and could be an option for those who loved the Bostons of old and want to give the line another shot. If you are a Lightstrike Pro fan, you will likely enjoy this as a training companion for your Adios Pro 2 or 3 because it does have a somewhat similar feel. It also has the classic Continental outsole, which still looks fresh (and also is fresh after >250 miles on my version 10), and therefore is bound to give you lots of durability. Overall firmness is another consideration. If you want a shoe rotation that has some shoes that are soft and mushy and others that are slightly firmer to give a good variety of underfoot feel, this one can sit on the firmer end of the spectrum for you.
David: The Adidas Adizero Boston 12 is a shoe for someone that wants a training companion that still feels like a training shoe but performs. The overall experience is on the firmer end with the Lightstrike 2.0 throughout the midsole, though the combination of Lightstrike Pro and the Energy Rods in the forefoot create a very lively forefoot transition. The lateral bias in the heel quickly transitions you forward and lets you engage the shoe in a different way than the last couple of Boston models. The Boston 12 is a great shoe for those wanting versatility in their training companion including warm up, workout, cool down, long run tempos.
GRADING
Matt
Fit: B (Lighter engineered mesh with low volume but a little more forefoot width. Not secure with lateral motion and not great midfoot lockdown)
Performance: A (Able to handle easy runs up to faster workouts. Versatile at a variety of paces as a performance trainer)
Stability: B/B+ [Neutral] (Medial bias at midfoot with mildly stable forefoot)
DPT/Footwear Science: B (Solid updates reducing weight, improving responsiveness and returning Boston to its rightful place as a performance trainer. However, the loss of stability partially from medial bias due to a "show" piece of the rods is concerning)
Personal: B+/A- (Great uptempo/performance trainer for mileage and workouts. Not quite stable enough for me to keep using for everything, but a fun ride. More biased toward faster efforts now than training.
Overall: B+
Nathan
Fit: C+/B- (Light and secure midfoot, but not comfortable, low volume in toe box, not enough heel padding, and odd lacing)
Performance: B+ (Smooth transitions, a bit of pop when picking up the pace, still smooth at slow)
Stability: B/B+ (Slight changes in drop, softness, and cutout position make this a neutral shoe)
DPT/Footwear Science: B (Good improvements with midsole foam composition, but nothing remarkable)
Personal: B+ (If fit was better for me I'd use this a lot more)
Overall: B/B+
David
Fit: B+ (Secure lockdown throughout, not much padding in heel, pressure from lateral stitching and sidewall integration)
Performance: A (Very versatile and fun to pick up the pace in. Still able to run easy miles. Quick and fast transitions with poppy forefoot.)
Stability: B/B+ (Definitely neutral, lateral bias does pitch you medially quickly, though forefoot sole flare, upper security, and traction help)
DPT/Footwear Science: B (A solid progression of the Boston line. Using similar materials and changing the combination a tad.)
Personal: A (Outside of the lateral stitch/sidewall pressure one of my favorite shoes this year)
Overall: B+/A-
SHOP | SUPPORT DORAdidas Adizero Boston 12Price: $159.95 at Running Warehouse
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New Balanace FuelCell Propel v4 - Version 4 adds a forefoot plate to this budget trainer
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Reebok Floatride Energy 5 - Major changes to the popular training series, including a torsion system
Salomon Aero Blaze - A new lightweight trainer from Salomon
Saucony Echelon 9 [Stable Neutral Trainer] - A wide-fitting, high cushion shoe that also fits orthotics perfectly well
Saucony Kinvara 14 - Higher stacked than ever, and lighter as well
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Topo Phantom 3 [Stable Neutral] - A daily training shoe with a fantastic upper and simple, functional ride
Tracksmith Eliot Runner - All-new trainer from the apparel brand, featuring a peba midsole
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