Kiprun KD900 X LD Review: A Budget Carbon Racer With Real Appeal

Introduction

The Kiprun KD900 X LD is the youngest sibling to Decathlon’s KD900 X carbon racer, designed for speed and racing. It was created in just eight months, which is a fast turnaround, and it is lighter than the previous model. Research also suggests it should boost energy efficiency over that earlier shoe. We put it through a series of hard runs, including a full marathon test fresh out of the box, to see whether it can compete with the big-hitting rivals on the market.

Design and Specifications

The stack height comes in at 36.8mm in the heel and 32.8mm in the forefoot, giving a reduced 4mm drop compared to 8mm on the previous KD900 X. That makes this one of the lowest-stack carbon racers currently on the shelves. In a UK men’s 8.5 test size it weighs in at 222g (7.8oz), and the official figures put it at 10% lighter than the past generation shoe. Pricing is around £160 in the UK, though the shoe will not be sold in the US or Australia.

The midsole has been updated with the new V Foam Plus, wrapped around a full-length carbon plate. The platform is quite narrow compared to something like the Alphafly or the New Balance SC Elite V4, particularly in the heel, and is more akin to the Adidas Adizero Metaspeed Sky Paris. A study carried out at the University of Franche-Comté found a 1.5% gain in running economy compared to the last-generation shoe. There is also a stone-catching cutout in the heel, presumably to save weight.

The upper features an open knit mesh that balances structure, flex, and breathability. The heel collar is minimal with two internal pads, and around the ankle you get a non-gusseted wrap tongue with a small amount of pinch padding. The outsole uses a fairly standard carbon shoe rubber covering, with generous forefoot pads and thick rubber in the higher-impact heel areas, which bodes well for durability.

Fit and Sizing

Sizing is where this shoe gets complicated. One tester ran in a regular UK 8.5 and got a good secure lockdown after using all the lace eyelets, but during a marathon test experienced cutting on the left ankle and blistering from the high heel collar. Another tester found the UK 9 noticeably longer than most racing shoes in the same size, with too much space in the toe box, and had the plastic strip on the upper cut skin under the ankle on a hard first run. That strip is simply a bit too firm and unyielding for a long-distance racing shoe.

The general advice is to go true to size, but be aware of the length and the firm plastic section near the ankle collar. Neither tester put the issues down to unwanted movement in the shoe; lockdown itself was secure and comfort overall was good, so these are upper design glitches worth watching for if you have sensitive ankle areas.

Ride and Performance

Underfoot, the ride is comfortable and stable, but the foam does not pack the punch of the best carbon racers. It shares some traits with the Metaspeed Sky Paris in terms of a narrow platform offering precision and agility, but it is nowhere near as energetic or aggressive. The ride sits closer to super trainer territory than the springiest carbon racing shoes, and it is not as stiff or punchy as a Vaporfly.

During a 13-mile stretch at marathon pace, there was some road shock coming up through one foot, which levelled out after a point and never grew beyond mild discomfort. At slower paces with more ragged form, the shoe did a relatively good job of offering both stability and enough cushioning in the final six miles on tired legs. The slightly less aggressive geometry actually gives you more stability than something like the Metaspeed Sky Paris.

On the track, in a hard session of marathon-pace tempo work followed by 12 x 400m reps, the shoe felt fast, light, and nimble, and cruised comfortably at marathon pace. It is not noticeably propulsive or rocket-like compared to other super shoes, and the 4mm drop is noticeable, with a somewhat flat ride. But it does make harder paces feel a bit easier, which is exactly what you want from a super shoe. Compared to the original KD900 X, the new foam brings a softer, bouncier feeling and makes it easier to unlock propulsion from the plate, making it a genuinely faster shoe all around.

Durability and Long-Term Use

The thick heel rubber performed well over 35 miles of mixed testing, including some slick riverside trails between road sections, where traction felt good. The original KD900 X was known for lasting a long time, and there is nothing in this version to suggest the outsole will be any less durable. Because the ride is slightly less aggressive, this also works well as a fast training and tempo shoe, which spreads the value over more running and suggests it will hold up better to high mileage than the top-tier super shoes.

Buying Advice

Is this the best carbon racing shoe? No. It is not the punchiest or the most cushioned. But it offers a well-balanced ride with enough energy to be interesting when you are running fast in good form, plus just enough protection to be reliable later into longer races. At around £160, it sits at super trainer money while delivering a higher level of racing performance than most super trainers.

The main caveat: older super shoes such as the Vaporfly, Metaspeed Sky Plus, or Adios Pro 3 frequently appear in sales around this price or lower, and those would be the better pure racing option. But at list price, this is very good value, and if the fit works for you, it is a genuinely capable marathon-capable racer. Someone fully invested in racing might still spend more on a top carbon shoe, but for a budget racer that can double as a fast trainer, this is one of the strongest options available.

Conclusion

The Kiprun KD900 X LD is a real step up from Decathlon’s first carbon racing effort: lighter, more efficient, and more versatile, all at a price that undercuts most of its competition. Fit quirks around the ankle collar and shoe length are worth checking before you commit, but if they do not affect you, this is an accomplished, fast, and impressively priced carbon racer.