KIPRUN KD900X Review

 

Key Stats

Price: $189.90 SGD

Stack Height: 37/29mm stack (8mm Drop)

Weight: 237grams / 8.36oz (Men's US 9.5)

Pros & Cons

Pros	Cons
Relatively Affordable Durable Breathable Upper	Firm, Stiff Ride Rough Upper Material Some Heel Chaffing

Background

The carbon plated shoe industry has become the most widely discussed subject in the world of running with the release of the Nike Vaporfly 4% a couple of years ago. With these plated shoes, runners felt that they were moving more quickly with less effort. However, these benefits are accompanied by two drawbacks: exorbitant cost and poor durability. While costing 1.5x-2x more than regular running trainers, these racers only had half the durability. Few runners were willing to invest $300 on a pair of running shoes that would only last them less than six months.

Enter Decathlon, a retail giant with a vision to make sporting goods accessible to the general public. Their first foray into the carbon-plated shoe industry, the KD900X, offers a novel value proposition: providing a wider audience access to carbon-plated shoes through a cost-effective and environmentally friendly solution. 

Coming in at $189.90 SGD, the KD900X is roughly 30% cheaper than current market offerings. The racer from Decathlon is also twice as durable as the pairs from industry leaders, with a claimed 1000km mileage.

Upper

The upper is made from a thin, well-ventilated mesh. The first thing that i noticed when i put it on was that it was a little unrefined. In other words, there were areas that felt stiff and 'scratchy' on my foot, especially on the instep. The upper resembles both the Peak UP30 Elite and the 361 Flame, which have rougher-feeling uppers and unstructured heel parts. Thicker socks help to solve this issue, though those wearing thin or no socks might face a problem.

Fit wise the KD900X is true to size, with decent room in the toebox. Shorter socks caused some heel rubbing for me, which is caused by the higher heel cup that extends halfway up the achilles. I believe that future iterations can shorten the heel cup while adding a touch of rigidity for a more structured fit and foot security. 

Midsole & Ride

The KD900X utilizes a Pebax® Arkema foam: 'VFOAM', a pelleted version of PEBA. Pelleted versions of PEBA tend to be firmer than typical PEBA foam, but also lasts longer. (The Saucony PWRRUN PB being an exception with its softer formulation this year). The VFOAM has a measured durometer of 31-33 (Shore A), which on paper is similar to the Nike Vaporfly Next % 2, but feels much firmer in reality. This drastic difference in feel is influenced by the position and rigidity of the carbon fiber plate, as well as outsole rubber hardness. 

The ride can be summed up in three words: firm, rigid, and stable. Frankly, running in the KD900X does not feel like running in a typical supershoe. The firmness and stiffness work well for shorter, faster efforts, but are more taxing on my legs compared to market competitors. I find myself to be working harder in this shoe compared to other plated shoes i've tried. I find that I'm able to get the most out of the shoe when performing faster efforts, but it's borderline harsh on slower efforts.

The firm ride translates into a highly stable ride. The best way I can describe the ride is that its a firmer and stiffer version of the first two versions of the Saucony Endorphin Pro. This ride characteristics might appeal to those who dislike the soft nature of carbon plated shoes and seek stability. 

I think that three changes can be made for a dramatically improved ride here: introducing a sharper curvature of the plate, and lowering the durometer of the VFOAM. The tools are there, but the current setup can be fine tuned to truly become a competitor in the carbon plated market.

Outsole & Durability

The KD900X features a generous rubber outsole in the forefoot and heel sections, with a pattern similar to most carbon plated shoes on the market. Decathlon promises a 1000km mileage out of the racer, which is twice of what one would expect in a plated shoe. 

While durable, the 3mm outsole increases the shoe's weight. Decathlon could consider doing away with some of the rubber in the forefoot (reference to the Endorphin Pro 3). By doing so, they would be able to preserve the shoe's durability while also reducing its overall weight. At 237grams for my US 9.5, it is on the heavier end of plated shoes. It falls into the same weight category as the Xtep 160x 3.0 Pro, Peak UP30 Elite and 361 Hurricane. To compete with other running manufacturers, adding rubber cutouts may help reduce the weight to the 200–220gram range.

With the exception of the Xtep 160x Pro, the grip is among the finest in plated shoes. (Somehow Xtep has managed to product long lasting outsoles which are light, grippy and very durable) Taking corners in both wet and dry conditions never posed a problem. 

Suggested Improvements

• Sharper Curvature of Carbon Plate
• Lower Foam Durometer (Softer Foam)
• Refine Upper Materials
• Slightly Shorten Heel Cup
• Introduce Strategic Outsole Cutouts

Summary

The Kiprun KD900X is best suited for runners who are new to the carbon-plated shoe market and are seeking for a stable and relatively inexpensive racing shoe for distances of 5–10 km. More seasoned runners will be able to take this up to a half marathon distance. It is a good debut effort by Decathlon, though several areas of improvement need to be looked into to compete with the likes of the top running shoe brands in the world.