There is a runner you will meet at every TCS World 10K start pen in Bengaluru. They are on the morning of their first sub-1:40 half. They have one carbon plate to spend and ₹14,000 to spend it on. They are choosing between the Adidas Adizero Boston 12 at ₹13,499 and the Asics Magic Speed 4 at ₹13,999. They will pick wrong if nobody tells them what the two shoes are actually for. This is that telling.
The verified specs, exactly as the brands publish them
Strip away the marketing for a moment. The numbers below are the only honest thing in the conversation.
| Spec | Adidas Adizero Boston 12 | Asics Magic Speed 4 |
|---|---|---|
| Brand | Adidas | Asics |
| Category | Tempo / plated trainer | Tempo / plated trainer |
| Drop | 6.5 mm | 5 mm |
| Heel stack | 37 mm | 38 mm |
| Forefoot stack | 30.5 mm | 33 mm |
| Weight (US 9) | 250 g | 218 g |
| Foam | Lightstrike Pro + EVA | FF Turbo+ + FF Blast Plus |
| Plate | Carbon EnergyRods | Carbon |
| Best for | Long-run / tempo training | Tempo / half marathon racing |
| India price | ₹13,499 | ₹13,999 |
The Boston weighs 250 g. The Magic Speed weighs 218 g. That is a 32 g gap, and that gap is the entire story of this comparison, hiding inside what looks like a similar shoe at a similar price in the same category. 32 g, in carbon-plated tempo trainer terms, is the difference between a workout shoe you also race in occasionally and a racing shoe you also workout in occasionally. The order of those words matters.
The category they share is a category with two doors
Tempo plus plated trainer. The phrase is doing a lot of unstated work. There are two kinds of runner walking through that doorway. The first lives in the training week. The second lives on race day. The shoes they need are different, even when both shoes are categorised as the same thing on the same retailer page.
The first runner buys this shoe to make their long runs faster and their tempo workouts more economical. They will run forty kilometres a week in the shoe. They will line up for a marathon and wear a separate race-day racer for that, or wear this same shoe because the race calendar did not allow for two shoes this season. Their priority is durability, weight tolerance under repeated long-run fatigue, and a ride that does not punish a 5:30 per kilometre pace because the shoe is busy waiting for 4:30. For this runner, the Adidas Boston 12 is the shoe.
The second runner buys this shoe to race. They want it on their feet for ten kilometres at threshold pace on a Tuesday, eight kilometres of marathon-pace work on a Sunday, and twenty-one kilometres of race pace on a Sunday in November when their bib has the word HALF on it. They do not need their tempo shoe to also be their long-run shoe. They have other shoes for the easy days. They want this one fast, light, sharp, and forgiving enough at half marathon distance not to fall apart at kilometre eighteen. For this runner, the Asics Magic Speed 4 is the shoe.
The Adidas Adizero Boston 12, read as a long-run truth-teller
The Boston has always been a strange shoe in the Adizero family. It is the only carbon-plated Adidas trainer that openly admits it is not a racer. Lightstrike Pro foam in the top layer, an EVA carrier below it. Carbon EnergyRods, plural, instead of a single rigid plate. 37 mm heel and 30.5 mm forefoot stack. 250 g on the foot. Read those numbers slowly and a picture comes out clearly. This is a long-run shoe with a plated engine inside it, not a half-marathon racer pretending it can do daily duty.
The EnergyRods themselves are the design choice that gives the shoe its character. Five carbon rods running through the midsole instead of one plate. They guide the foot into a propulsive forefoot roll without locking it into the single bend pattern that a stiff carbon plate imposes. On a 25 km marathon-block long run at goal pace, that compliance is the entire point. Your gait will drift across three hours. The Boston lets it drift and still rolls you forward. A stiffer carbon racer would force you to fight the shoe in the last 5 km, and you would lose that fight, because you were never trying to win it.
Who the Adidas Boston 12 is actually for
The 70 to 90 km weekly marathoner who wants one shoe that handles tempo workouts on Tuesday, marathon-pace long runs on Sunday, and a backup race-day option if their primary race shoe gets eaten by Bengaluru rain in October. The half-marathoner stepping up to a full who wants one tool that learns both distances. The runner under 80 kg who weighs less than the 250 g shoe is built for, gets the durability without the weight penalty becoming the story.
Pair it with a cushioned daily trainer for the easy days, and the Boston becomes the workhorse of a real two-shoe rotation under ₹25,000. Read the long-form on it at the Boston 12 review and check the wider Adidas compare hub for where it sits next to the Adios Pro and the Boston 11.
The Asics Magic Speed 4, read as a small racing animal
218 g. Read that number again. 218 g is racing weight. That is what the conversation needs to start with, because every other paragraph about the Magic Speed 4 follows from those two numbers. A 5 mm drop. A 33 mm forefoot stack on a 38 mm heel stack. A full carbon plate, not split into rods. FF Turbo plus and FF Blast Plus, the same foam family Asics uses in the Metaspeed Sky and the Metaspeed Edge.
What that combination produces, under your foot, is a smaller, sharper, more honest version of the Metaspeed at slightly under half the price. The Magic Speed 4 does not pretend to be a sub-2:05 marathon shoe. It is sized, weighted and priced to be the shoe an amateur Indian runner can actually race a half marathon in without spending ₹22,000 on the headline racer.
The 32 g it saves against the Boston 12 is not a marketing number. Over a 21.1 km half marathon at a 4:45 per kilometre pace, your foot lifts that 32 g roughly 18,000 times. Felt across a hundred minutes of racing, that is a meaningful tax. The Magic Speed refuses to pay it. The Boston pays it gladly, because the Boston is paying it across a 30 km easy long run where the weight is being repaid in long-haul durability instead.
Who the Asics Magic Speed 4 is actually for
The half marathon racer chasing a sub-1:40 or sub-1:30 personal best who does not yet want to spend ₹22,000 on a top-tier racer. The 10K specialist who runs 35 to 50 km a week and wants one carbon shoe for tempo sessions and short races up to 21.1 km. The light, efficient runner under 65 kg whose stride does not need a heavier shoe to feel stable under it.
Pair it with a cushioned daily trainer for the easy days and a long-run shoe for the long runs, and you have a three-shoe rotation built around the Magic Speed as the workout and short-race tool. The Adidas Boston has the wrong weight profile for that runner. For that runner, the Magic Speed wins on the spec sheet and wins on the road. Read its long-form review and the wider Asics compare hub for where it sits next to the Metaspeed family.
India context — heat, monsoon, real availability
Both shoes retail through their brand sites and authorised speciality stores. Adidas runs through adidas.co.in and authorised running retail in Bengaluru, Mumbai, Delhi, Hyderabad and Pune. Asics runs through asics.in and Asics-branded retail in the same metros. Both brands have a counterfeit problem in grey-market listings, and the midsole foam is the part that fakes copy worst. You cannot see a fake midsole. You only feel it three weeks in, when the bounce is gone and the shoe is dead.
Monsoon. Both uppers are race-engineered mesh. Neither pretends to be waterproof. The Magic Speed's lighter upper drains slightly faster and dries slightly quicker, which matters more for a half marathon race day in late September than for a Tuesday tempo session. The Boston's slightly more enclosed upper holds water longer but takes more abuse from the broken tarmac that long runs in Indian metros tend to include. Trade-offs, not failures.
Heat. The Magic Speed runs cooler because it weighs less and sits a touch lower. The Boston holds heat marginally longer at a higher stack and weight. Neither difference is large enough to be the reason you pick a shoe. Both will be uncomfortable in Chennai in May.
The verdict, by use case, with no fence-sitting
If you are racing your first sub-1:40 half marathon and you have one carbon shoe to buy this year, the Asics Magic Speed 4 wins at ₹13,999. The 218 g weight, the full carbon plate, the FF Turbo plus foam, all of it is engineered for the question you are asking. The 32 g it saves the Boston is the difference between a half marathon PB and a half marathon finish.
If you are training for your first marathon under 4 hours and you have one carbon shoe to buy this year, the Adidas Adizero Boston 12 wins at ₹13,499. The 250 g weight is the price you pay for the Lightstrike Pro foam holding up across 70 km weeks, and the carbon EnergyRods are the propulsive system you want for marathon-pace work that does not punish a slightly off-pace long run.
If you are buying one carbon shoe to do everything for the next twelve months, neither shoe is right for everything, but the Boston covers more of the use cases. Long runs, tempo, marathon race day, half marathon if you must. The Magic Speed is sharper on race day and weaker on long-run duty. Pick the Boston for breadth, the Magic Speed for sharpness.
Cross-check the math at the shoe comparison tool, and browse the wider Running Lab for the rest of the carbon-plated tempo field. Once the shoe is sorted, build the weeks around it with the STRIDD plan generator, because the right shoe in the wrong week is the wrong shoe in disguise.