Royal Parks Half Marathon Gear Test: Six Pieces of Kit Put Through Race Conditions

Introduction

Race day is where kit claims meet reality, and the Royal Parks Half Marathon offered the perfect proving ground: a twisty, tree-lined course through London’s parks with more corners and hidden hills than you would expect. Two runners lined up with a plan: one testing the Adidas Adizero Prime X Strung and an Apple Watch Ultra in low power mode, the other running the Adidas Super Comp Trainer with the same watch at full brightness. Add in Tracksmith shorts, Stance socks, and a Garmin Enduro riding along, and you have a genuine field test rather than a desk review.

Neither runner was at full fitness, both were carrying a cold, and both knowingly raced in shoes that are not competition-legal. That is worth knowing up front, because the verdicts here are about how the gear behaves in race conditions, not about podium legalities.

The Setting: A Real Race Course Test

The Royal Parks Half is a course with character. The route twists through the parks, includes stretches that echo the London Marathon, and delivers a few sneaky inclines that catch you off guard. It is narrower and busier than many big-city races, with plenty of weaving through crowds, which matters more than you might think when you are racing in shoes with a very large footprint.

That twisty profile turned out to be the defining factor of the day. It separated the gear that thrives anywhere from the kit that belongs on a fast, straight course.

Adidas Adizero Prime X Strung: Fun, Fast, and Totally Illegal

The Adizero Prime X Strung is a maximal carbon race shoe: a massive 50mm stack of Lightstrike Pro foam stacked in three layers, topped with a new strung upper on a Primex-style bottom unit. None of that is race legal, so any personal best recorded in them would not officially count. The point of the test was simply how they feel in proper race conditions.

The answer: enormous fun for the first miles. They are bouncy, springy, and the strung uppers are a huge step forward in comfort compared with the Adios Pro 2, whose uppers were the main complaint. The verdict here was that these are the best super shoes tried so far for feel and comfort, with the upper making a genuinely noticeable difference.

The caveat is stability. With a 50mm stack and a wide platform, the twisty course made them hard work. On tight corners and uneven cambers, the foot occasionally slid off the base and required real effort to recover the next step. These are shoes for straight, fast courses, not for round-the-bend city routes. If the next generation of Adios Pro racing shoes adopts the strung upper, that alone would be worth the upgrade.

Adidas Super Comp Trainer: Bouncy Daily Miles with Race DNA

The Super Comp Trainer was originally picked for London Marathon plans, and it is easy to see why. With a 47mm heel stack, it delivers that bouncy, big-stack sensation even though it is also technically outside race rules. On a half marathon, the first miles felt genuinely fun and cushioned.

The trade-off mirrors the Prime X: a big platform is not built for twisty courses. On a bend-heavy route like Royal Parks, there were moments where the extra height made cornering feel precarious, though nothing worse than a wobble. On a straighter course, these would shine.

If you love the feel of a big, soft, springy midsole and your target race is flat and fast, the Super Comp Trainer makes a strong case as a trainer that flirts with racer territory.

Apple Watch Ultra: Low Power Mode vs Full Power

The watch test produced the most surprising result of the day. One Apple Watch Ultra ran the entire half marathon in full power mode, everything on, screen bright, music playing, and finished at 92% battery. The other, set to low power mode specifically to test battery endurance and GPS reliability, dropped from 67% to 57% over the same race.

The full-power watch was piggybacking a phone for GPS, which may explain part of the difference, but it was still an unexpected outcome for a low power battery test. The GPS accuracy itself was reassuring: recorded distances came in at roughly 13.29 and 13.3 miles against a 13.1 official distance, which is normal overage on a weave-heavy course.

One practical annoyance worth flagging: notifications kept buzzing in throughout the race, and switching those off is not the most obvious setting to find. Worth sorting before race morning.

Garmin Enduro: The Reference Point

The Garmin Enduro was worn as a second watch and its GPS track essentially agreed with the Apple Watch Ultra throughout the race. Both measured just over the official half marathon distance, in line with the expected margin of error when weaving through crowds. That cross-agreement gave confidence that the Ultra’s GPS performance, even in low power mode, was solid.

The Enduro’s role here was the quiet benchmark: a watch that just recorded the race without drama and matched the data.

Running on Feel: Covering the Watches

Both runners taped over or covered their watches entirely and ran the race on feel, using heart rate as a guide only. It worked before at the New Forest Marathon, and it mostly worked here, though both admitted going out a little too fast in the early miles, as everyone does.

The takeaway is simple: running blind can be a genuinely useful pacing exercise, especially coming back from illness when pace numbers are more distracting than helpful. Just be ready for the slight overreach at the start.

Tracksmith Austin Shorts and Stance Socks

The Tracksmith Austin shorts are minimal by design: a pocket at the back and not much else. The verdict after 13.1 miles was that they were super comfortable, did not ride up, and the lack of leg storage was not missed on a short race where fueling needs were light. For longer efforts where you carry more, that could be a different story.

First-time racing in Stance performance socks was a small surprise. The initial impression was that they felt quite thick for racing, but they turned out to be very comfortable over the full distance.

Overall Buying Advice

Context matters more than specs. The Prime X Strung and Super Comp Trainer are both spectacular on straight, fast courses and compromised on twisty ones, so buy for your target race profile, not just the stack height. The Apple Watch Ultra proved accurate and surprisingly efficient at full power, and the Garmin Enduro remains a dependable benchmark. The Austin shorts and Stance socks are the easy, low-risk picks of the bunch: comfortable, uncomplicated, and race-ready.

If your next race is flat and fast, the big-stack Adidas options deserve serious consideration. If your race has corners, keep the stacked shoes for training miles and race in something more stable.

Conclusion

Six pieces of kit, one twisty half marathon, and two cold-affected runners later, the results were clear. The strung upper on the Prime X Strung is a genuine comfort leap, the Super Comp Trainer is bouncy fun with a cornering caveat, the Apple Watch Ultra delivered accurate GPS and a battery surprise, the Garmin Enduro quietly confirmed it all, and the shorts and socks simply worked. Match the gear to the course and you will get the most out of all of it.