Kiprun KD900x - a first try with GOOD and BAD things

Can the positives of the Kiprun KD900x outweigh its drawbacks?

Summary

Tim: Early Autumn this year Kiprun is launching its first plated shoe. The brand’s goal is “simple” – offering a competitive shoe with a great energy return that lasts more than other racers (claimed durability is ~1.000km) for a (rather) competitive price of 150€. Did they deliver ?

Kiprun KD900x – Specs

Weight: Official: 221g in US9 – Actual: 251g (8.8oz) in size US11 / EU45

Stack height (forefoot/heel): 37/29mm

Durometer score (0 to 100, soft to hard): 26.1/100 for the PEBAX-based VFoam midsole compound

The platform is standard in terms of width. For specific values, please check the Shoe Comparator in which you can compare the width for the forefoot, midfoot and heel against other shoes.

Upper: a stiff material and a specific heel design

Tim: As you will read in this review, the KD900X comes with some nice features as well as less positive ones in every part of the shoe. But first let’s begin with the fit. The footwear is a bit large compared to other shoes. Therefore I would maybe consider going half a size down. Note however that all half-size increments are not available. If “half down”doesn’t exist for you I would recommend sticking with your true to size.

Things that worked for me : the upper is thin and breathable. Even under high temperatures that we experienced this year, I didn’t feel any overheating. Regarding the laces, they work well and the feet are well maintained in the shoe. Lastly, for those who like to have a soft heel counter the shoe should give you satisfaction on that front.

Things that don’t work for me : even if the upper is thin, it’s not smooth. The upper is a bit stiff and rough, which is unpleasant especially around the tongue and the lace cage area. Moreover, in the heel counter / heel area the shape doesn’t fit my foot well. I ran once with thin socks and had blisters. Since then I always used thicker socks and never had blisters again.

Alex: Putting the look aside (although I think Kiprun nailed that design – like it or not), the upper is always the first thing your feet get to experience when running in a new pair of shoes. You put them on and your feet “react” to the sensation they are greeted with by the upper. That first hello isn’t necessarily a good one on this shoe. The upper is rigid, stiff and that creates unpleasant creases in the forefoot. It did loosen up a tad in the two months of testing I had with this shoe. But not sufficiently to call it a nice upper either.

I do not concur with Tim’s views on the sizing. I think this is a true to size fit. It’s even rather on the snugger side in the midfoot. That being said the midfoot lockdowns is good thanks to that. It is also helped by the lacing system, which goes through the tongue and secures the fit.

The tongue is not much better for me compared to the upper overall. It’s also rather rough and goes too high on top of my feet.

I agree with Tim, the heel cup is tricky and may be the source of friction for some of you out there. Note that the removable insole is on the thicker side and switching with something thinner may help to sit your heel lower.

Midsole and ride – the Kiprun KD900x will surprise you where you don’t expect it to

Tim: Stiffness is the word that comes to mind when thinking about the KD900X. Is it due to the density of the foam, the way the carbon plate is placed or both ? Whatever the technical answer may be, the stiffness is in the meantime the source of its main strengths as well as its biggest drawback.

On the strength side, I noticed the very good stability of the shoe especially in the range of plated shoes. Thanks to that and the lockdown I wrote about above, I feel secure when running at higher paces (and I’m confident if I see a turn coming). Moreover I also have the feeling that Kiprun decided to give the foam a high density, and therefore a bit of stiffness, to reach its goal of having a shoe that still be competitive to the 1.000km mark.

On the drawback side, its extreme stiffness didn’t allow me to feel this feeling of fatigue reduction especially for paces below 4’30/km (7’14/mile). Instead I even had the feeling that the shoe is more muscle demanding and I ended most of my interval sessions with my calves and hamstrings quite tense.

Regarding the energy return, the faster you run the more you feel it. In my case I really feel it for 5km pace and a bit for 10km but not for more. Therefore I would personally recommend this shoe for interval training or races but not over 10km.

Alex: When you hear Pebax, what’s the first thing you’re thinking of? Come on let’s be real. It has to be the Vaporfly. At least for many runners – geeky ones I’ll admit – Pebax is associated with ZoomX, the foam compound of Nike racing shoes. And first things first, let’s give kudos to Decathlon for partnering up with the French chemical company – and Pebax producer – Arkema. Many brands out there still haven’t jumped in the superfoam game and I believe Kiprun did a great job of getting there with their first plated racing shoe. Now is Pebax as good as Pebax? Or reading in between the lines, is VFoam (Kiprun’s foam name) as good as ZoomX? Short answer, no. Long answer, no…but it’s not necessarily down to Pebax.

First the way Pebax is used here is specific. It’s an aggregation of small foam pellets like on Saucony’s Pwrrun PB. That structure probably explains the low durometer score. However the score does not correlate at all with the ride of the shoe. And that’s probably due to the plate properties. The ride for me was muted until reaching faster paces. All across the board it was on the stiffer side of things and even after more than 50kms in the shoe, the midsole did not get softer. Some good things though: like Tim wrote, the ride is mega stable (in the realm of plated shoes, think Hyperion Elite 2).

If you’re a forefoot striker with a strong toe-off, you’ll enjoy this ride more than if you’re expecting an accompanying roll. On the track, the tartan gives to that ride a sweeter flavor and honestly that’s where the shoe felt best for me. That’s very hypothetical (because I don’t do track meets and this shoe isn’t track legal): my preferred way of using this shoe would be for 3000m or 5000m races on the track.

Outsole – where it all makes sense

Tim : Kiprun is promising a shoe that lasts for 1.000km and would still be competitive around that lifespan. According to their press release they even have testers who ran around 1.500km with the shoe. Let’s be honest, it’s a huge amount of km. Far away from the figures we are used to seeing in this shoe category. To deliver this Kiprun added ~4mm of rubber on the main part of the outsole. This indeed increases the shoe lifetime but at the expense of the weight. My own experience with this rubber outsole is good for both the grip, which is one of the best I ever tried on a plated road shoe, and the lifetime. As I’m writing this review I ran nearly 100 km with the KD900x and don’t see any specific wear on the outsole. Therefore I can not say whether the shoe will last 1.000km but I’m confident that it will last longer than most of its direct competitors.

Alex : I don’t have much to add to Tim’s input here. The outsole makes sense both from the marketing perspective and from the functionality one too. You cannot claim a 1,000kms durability without coming up with something like this outsole. Yes, it’s on the thicker side. Yes, it probably contributes to muting that ride even further. But at the same time it gives you way more bang for your buck that other racers if it helps you taking that shoe to the 1,000kms mark.

Conclusion – mission accomplished…now we want more

Tim : Plated shoes are nowadays an essential product for every running shoe brand. With the KD900x Kiprun joins the game and completes its already wide product range with a competitive plated shoe. In my opinion this first attempt has some very interesting features like the price and the claimed lifetime (quite insane compared to competitors and market trend) as well as the stability. It also has some drawbacks with that highly rigid upper and the fit of the heel area that doesn’t work for my feet. In my case the drawbacks are too important to add this shoe to my rotation. But according to the fact that it’s the first plated shoe of the French brand, I would say that it’s promising and I’m already excited to see the v2 !

Alex : Kiprun just entered another dimension with their first carbon plated racer. Not only because of that, but because of how good the price is when you think of the specs. Any other sub €150 racing shoe with Pebax? Not that I can think of (ok excluding sales and discounts). Yes it has some flaws. But most of what I personally attempt to do for the first isn’t perfect either. Now that they have the kitchen and utensils, let’s give them a bit of time to make that recipe perfect.