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40Race Shoe FinderEst. 2023 · London

Head to head

adidas Prime X 3 Strungvs
HOKA Skyward X

Prime X 3 Strung

£149

Typical street price · £250 RRP

■ 50mm — over limit
Skyward X

£190

Typical street price · £225 RRP

■ 48mm — over limit

Choose the Prime X 3 Strung if…

  • You want the bigger return: 3–4.2% economy gain against 1.6–2.8%, and that gap widens the longer you are out there.
  • You want the lighter shoe: 275g against 314g, a 39g difference you will feel late in a race.
  • You race off a strong, repeatable stride and want the more aggressive ride rather than the safer one.
  • You want a conventional fit rather than a narrow or wide last.
  • Money matters: it is selling around £149 against £190, and the time difference between them is smaller than the price difference suggests.

Choose the Skyward X if…

  • You want something more forgiving. This is the steadier platform — useful if your form goes late, or if you are on your feet longer.
  • You have a broad foot, or your toes spread as a long race goes on.
  • You want more races out of one pair: about 700km of competitive life against 500km.

What does this
mean for you?

Every figure below is recalculated from your race and your current time. The gap between two shoes is not fixed — it grows with how long you are on your feet.

Over marathon from 3:45:00

Time back
Prime X 3 Strung: 152s–233sSkyward X: 56s–138s
Cost per second saved
Prime X 3 Strung: £0.10Skyward X: £0.18

Ranges, not promises. Both figures are against a standard trainer, and the honest answer for most runners is that the difference between two shoes of this class is smaller than the difference a month of decent training makes.

Every number.

010203040505044
Prime X 3 Strung
010203040504843
Skyward X

What you pay

Street price
Prime X 3 Strung£149■
Skyward X£190

What the shoe is actually selling for across the shops we read, not its RRP.

RRP
Prime X 3 Strung£250
Skyward X£225

List price. Almost nobody pays it for a race shoe.

Cost per race
Prime X 3 Strung£19
Skyward X£17■

Street price divided by the races the foam stays fast for.

Cost per second saved
Prime X 3 Strung£0.10■
Skyward X£0.18

The whole-life question: what each second of race time costs you.

What it does

Estimated saving
Prime X 3 Strung152s–233s■
Skyward X56s–138s

Against a standard trainer, over the distance and time set above.

Economy gain
Prime X 3 Strung3–4.2%■
Skyward X1.6–2.8%
Built for
Prime X 3 StrungMarathon · Ultra
Skyward XMarathon · Ultra
Best use case
Prime X 3 StrungDeliberately built past the rules. Enormous stack, huge cushioning, and superb for long training runs or any race that does not apply World Athletics regulations.
Skyward XA cushioned plated trainer built for comfort over long, slow miles rather than speed.

How it is built

Weight
Prime X 3 Strung275 g■
Skyward X314 g

Manufacturer figure at men's US 9.

Stack (heel)
Prime X 3 Strung50 mm
Skyward X48 mm
Stack (forefoot)
Prime X 3 Strung44 mm
Skyward X43 mm
Drop
Prime X 3 Strung6 mm
Skyward X5 mm
Foam
Prime X 3 StrungLightstrike Pro
Skyward XPEBA over EVA
Plate
Prime X 3 Strungcarbon fibre
Skyward Xcarbon fibre

Rules and fit

Road legal
Prime X 3 StrungNo (50 mm)
Skyward XNo (48 mm)

World Athletics caps road racing shoes at 40 mm of stack.

Fit
Prime X 3 Strungstandard
Skyward Xwide
Stability
Prime X 3 Strungbalanced
Skyward Xstable

Neither is better in the abstract — it depends on your stride.

Race life
Prime X 3 Strung~500 km
Skyward X~700 km■

How long the foam stays fast, not how long the shoe survives.

Data confidence
Prime X 3 Strungverified
Skyward Xverified

■ marks the better figure where one is genuinely better. Fit, foam, drop and stability carry no mark — they depend on your foot and your stride, not on which shoe is superior.

In your size.

Where to buy

Your UK size

Best price today — some sizes£145at Runningbear — £105 under RRP

9 retailer checks failed on the last run, so their prices are missing rather than wrong.

Prices are captured when the site is built and stamped with the time of that check. We never rank a retailer by what it pays us; where a link earns a commission it is marked sponsored and the price you pay is unchanged.

Where to buy

Your UK size

Best price today — some sizes£185at Alexandra Sports — £40 under RRP

9 retailer checks failed on the last run, so their prices are missing rather than wrong.

Prices are captured when the site is built and stamped with the time of that check. We never rank a retailer by what it pays us; where a link earns a commission it is marked sponsored and the price you pay is unchanged.