From the top professionals posting eye-wateringly fast run splits in an Ironman marathon as they battle for podium places. To every day age-groupers taking an ‘every little helps’ approach to coaxing their poor, 112-mile bike ride-battered legs through a marathon after a long day out on the race course. Super shoes have become a staple item in many T2 transition bags in recent years.
But as the demand for ultra-bouncy, go-faster shoes grew. So too, did the stack heights as running brands pushed the envelope with chunky high energy return foam and multiple carbon plates. All that led to World Athletics banning shoes with a stack height over 40mm, and/or with more than one rigid embedded plate/blade from road-race competition in 2020. In 2023, World Triathlon adopted the policy and IRONMAN soon followed suit. Which led to the most recent announcement of the latest ‘illegal’ super shoes you won’t be allowed to go racing in this season. You can see the list here.
So which shoes CAN you wear? Here’s my top picks of the best marathon super shoes and carbon-plated running shoes that won’t get you a DQ at an IRONMAN-branded race.
Best marathon super shoes for Ironman
Later on in this article, I’ve brought you my pick of some of the slightly more budget-friendly running shoes that will deliver at least some of the speed and energy return of your classic super shoes – just without the super-charged price tag. But first, let’s look at the big hitters that fall within that 40mm or under IRONMAN (and World Athletics) legal bracket.
Nike Vaporfly 3
| Stack height: 40mm | Drop: 8mm |
| Weight: 200g (men’s) / 165g (women’s) | RRP: £249.99 / $325 |
| Key features: Improved stability, ZoomX foam, additional comfort features added | Best for: Heel strikers |
Often referred to as the OG super shoe, the first iteration of the Nike Vaporfly launched in 2017. They were named the Vaporfly 4% to reflect the claimed 4% improvement in running economy. The innovative shoe kicked off a new era for running shoe tech.
The latest version, the Vaporfly 3 is right on the boundary of being race-legal with it’s 40mm stack height. But I’ve double checked the World Athletics running shoe equivalent of Santa’s naughty and nice list, and they are approved for competition. I raced two full Ironman distances in mine last season. And while I’m by no means a fast runner – they did help me to achieve my ‘get a sub-4hr Ironman marathon time’ goal with 4 minutes to spare. I’ve run in older versions of these over the years and the Vaporfly 3s offer a bit more room in the toe box than previous iterations. There’s less lace pressure on the top of your foot in the latest version. And the stability under foot also feels better – I even wore them for a half marathon on mixed terrain (road, gravel, trail) recently and I was pleasantly surprised with the traction.
Of course there is also the Nike Alphaflys. I did get a pair of these a few years back but immediately exchanged them for trusty Vaporflys. For me, the Alphas just felt way too unstable and I’m wobbly enough in the latter stages of an Ironman.
ON Cloudboom Strike
| Stack height: 39.5mm | Drop: 4mm |
| Weight: 219g (men’s), 194g (women’s) | RRP: £260 / $337 |
| Key features: Carbon Speedboard®, max cushioning | Best for: Forefoot runners |
Never have I ever been more disappointed that medium-low drop running shoes don’t really work for me. Because if the Nike Vaporfly is the OG, grand-daddy of super shoes. The ON Cloudboom Strike feels like the fresh, trendy super shoe that all the cool kids will be racing in. They’ve even got Elmo on board. It almost makes me want to play injury roulette just so I can be part of that gang.
If lower drop shoes work for you, the Cloudboom Strike is certainly worth considering. Promising an ultra-cushioned ride combined with ON’s signature Helion™ HF hyper foam for energy return and a ‘spoon-shaped’ carbon fibre Speedboard® to give strong energy transfer and propulsion at toe off. Plus a super lightweight upper and a super stylish design.
ASICS Metaspeed Sky and Metaspeed Edge Paris
| Stack height: 39.5mm | Drop: 5mm |
| Weight: 185g | RRP: £220 / $285 |
| Key features: Lightweight, versions for different run styles | Best for: Mid to forefoot runners |
ASICS’ Superblast and Novablast shoes might have found themselves on IRONMAN’s naughty list. But the Metaspeed Paris series shoes are still very much race legal. The ‘Sky’ is aimed at stride runners, focusing on max propulsion per stride. And the Edge is targeted at cadence runners, focusing on fast take off. Both shoes feature a curved design to minimise energy lost during excess ankle flexion. And the latest versions have a wider carbon plate for even more spring in your step.
Saucony Endorphin Elite
| Stack height: 39.5mm | Drop: 8mm |
| Weight: 204g (men’s) / 185g (women’s) | RRP: £280 / $365 |
| Key features: Slotted carbon plate, ultra-breathable | Best for: Most types of foot strike |
I spent a season racing in the Saucony Endorphin Pro super shoes. Which I liked, but I didn’t love them enough to replace them like for like when they wore out – returning to the Nike Vaporfly. They performed well enough, but they just didn’t quite have the same snap and energy return as the Nikes. But the Endorphin Elite addresses that issue, with an improved slotted carbon plate levelling up the energy return and offering more responsiveness compared to the Endorphin Pro. You’ve also got a roomier toe box and wider mid-foot which is ideal for the Ironman marathon where your feet are likely to be a little hot and swollen after 112 miles in your bike shoes before you even think about starting the run. This also helps to improve lateral stability, which combined with the Pebax-based PWRRUN HG foam makes for a firmer feeling ride.
New Balance FuelCell SuperComp Elite V4
| Stack height: 40mm | Drop: 4mm |
| Weight: 241g (men’s) / 179g (women’s) | RRP: £260 / $337 |
| Key features: Thin full carbon plate, lightweight upper | Best for: Forefoot runners |
IRONMAN, on their list of banned shoes for 2025, has stated that the New Balance Supercomp shoes are, well, banned. However, the version of the New Balance Supercomp that had a stack height greater than 40mm is actually an old model – circa 2023. The most recent version, the SuperComp Elite V4 has a just-about-legal stack of 40mm, and World Athletics list them as approved for use. So technically, the latest version of the SuperComp should be fine to race in. I actually think the reduced stack will have made these shoes better, too. I ran in the old >40mm 2023 iteration for several months and while I enjoyed all that squishiness underfoot (I was returning from a small stress fracture at the time) they definitely didn’t feel at all energetic.
The SuperComp Elite V4s boast a full carbon plate, a lightweight design with strategic cut-outs to maximise energy return. And that parred back stack height should take away the marshmallow factor. Just consider that you may find yourself having to argue your case at an M-dot race if an overzealous tech official just sees SuperComp and assumes they’re illegal.
Hoka Cielo X1 2.0
| Stack height: 39mm | Drop: 7mm |
| Weight: 228g | RRP: £250 / $325 |
| Key features: Updated rocker, improved outsole traction | Best for: Most types of foot strike |
And finally, before we move on to a few options that won’t put quite so much of a dent in your new bike fund, is the Hoka Cielo X1 2.0. These Hoka running shoes come with their most racey rocker shape, combined with PEBA foam and a winged carbon plate. All designed to offer even more speed than the much-loved Rocket X2. Hoka have also improved the traction on the outsole of the Cielo X1 2.0s. The compromise for that extra pep in your step is stability. If you get on well with Hokas but you want something with a little more lateral stability, you might prefer the Rocket X2.
Best marathon running shoes for Ironman racing without the super high end price tag
It can be hard to justify spending close to £300 / $350 (in some cases) on one pair of running shoes. Especially when some of those super shoes are so performance-focused, they’ve compromised entirely on durability. Meaning you’ll have to replace them regularly if you race fairly often. Thankfully, there are some (relatively speaking) more affordable options out there that will still give you a boost of extra run speed.
Adidas Adizero Boston 12s
| Stack height: 38mm | Drop: 7mm |
| Weight: 260g | RRP: £140 / $180 |
| Key features: Carbon rods, customisable | Best for: Most types of foot strike |
The uber-chunky Adidas Prime series shoes are all on the banned list. But that doesn’t leave Adidas high and dry on the super shoes front. If you’re a big fan of the three stripes, you’ll be glad to know that there are a couple of super shoes options from Adidas that are race-legal. Of course, you have the Adizero Pro 4 running shoes at the more premium price point (~£220). But for an £80 saving with an RRP of £140, the Adidas Adizero Boston 12s are a great option for triathlon age-groupers trying to get through 26.2 miles of running with whatever our legs will give us after 112 miles on the bike.
These feature carbon rods, rather than a plate, and offer up plenty of energy return. But there’s less of a compromise on durability compared to other super shoes. That means you can do a couple of your longer training runs in them to make sure you’re happy before race day, without worrying about wearing them out. You might even get more than one race season out of them! For a small extra cost, you can also add custom text to your shoes. It won’t make you run faster, but it is kind of cool.
361 Degrees Flame 4
| Stack height: 36mm | Drop: 6mm |
| Weight: 210g | RRP: £146 / $190 |
| Key features: Carbon plate, high energy return midsole | Best for: Mid-fore foot runners |
The Flame 4 running shoes from 361 Degrees are a carbon plated running shoe at a pretty wallet-friendly price point. The “Qu!kBONE DYNAM!C” (yes, I am docking them some imaginary points here for the annoying use of unnecessary exclamation points) carbon plate has been designed with cut-outs for optimal propulsion. And the “Qu!kFLAMECQT” mid-sole promises bounce and energy savings, without adding too much additional weight to the shoe. The outsole has been upgraded for better grip and durability. And the upper is now made from ‘Carbon Silk’ which promises better breathability.
New Balance FuelCell Rebel 4
| Stack height: 30mm | Drop: 6mm |
| Weight: 211g (men’s) / 157.5g (women’s) | RRP: £140 / $180 |
| Key features: FuelCell responsive foam, versatile all-rounder | Best for: Mid-fore foot runners |
Pitched as an ‘everyday trainer’ with an extra boost of energy return that offers versatility across long steady runs and high tempo efforts. The New Balance FuelCell Rebel 4 will be an ideal choice if you’re not fussed about having a carbon plate, and you want a solid all-rounder that will take you from training to race day. The Rebel 4 is designed to feel propulsive and responsive underfoot, thanks to a blended PEBA/EVA foam. While still offering the cushioning, stability and durability you’ll need to tick off all the long training runs. The slightly lower 30mm stack height will give you more ground feel compared to other shoes on this list. Ideal if you don’t get on with towering, max cushioning. And the look and feel of the design still gives off a ‘race day vibe’, so you certainly won’t feel like you’re plodding around in your training shoes.
Hoka Mach X
| Stack height: 37mm | Drop: 5mm |
| Weight: | RRP: £170 / $220 |
| Key features: | Best for: Mid and forefoot runners |
The Hoka Mach X is pushing the limit of ‘budget-friendly’. But considering you’re saving between £80-£100 compared to the super shoe options – you’re still getting a decent amount of performance for the price tag. The Mach X has a Pebax® plate instead of carbon, which still gives good propulsion. This is tucked between PEBA and EVA foam providing cushioning without compromise on rebound. The rocker is more aggressive, adding to the propulsive feel. This, combined with the slimmed down design and lightweight construction, makes the Mach X a shoe that could quite easily take you from training to race day.
Quick fire recap/FAQs
IRONMAN have implemented rules already set by World Athletics to regulate ‘super shoes’ deemed to provide an unfair advantage. Stack heights must be no higher than 40mm and shoes cannot have more than one rigid carbon plate.
Quite simply, the amount of material between your foot and the ground – how ‘tall’ the sole of the running shoe is.
40mm is the maximum, though many shoe brands have opted for 39.5mm presumably just to be on the safe side!
PEBA is a specific type of foam used in high performance running shoes. It is designed to be ultra-lightweight, responsive and with high energy return. EVA foam is more commonly used in ‘every day’ running shoes where cushioning and stability is more of a priority than energy return and low density. Some mid-range shoes combine the two to offer the best of both worlds.
The drop of a running shoe refers to the difference in height between the heel of the shoe and the forefoot of the shoe. Read more over on RUN247!
A carbon plate in running shoes acts like a spring, maximising energy return when your foot hits the ground and adding propulsion. It also increases the shoe stiffness which helps to reduce energy loss.
IRONMAN have added a list of their known banned shoes here. You can also use the World Athletics list of approved shoes.
