In mid-August 2026, Decathlon refreshed its Kiprun trail range with several new products, including a brand-new pair of shorts: the Trail Run 900 Ultra x RHEON. The pitch: less muscle vibration thanks to a patented polymer the brand has already proven on a pair of running tights. At RunMorph, we break down this freshly launched product to see whether the technology delivers in a format built specifically for trail running.
© Decathlon, official photo used for editorial purposes
The Kiprun Trail Run 900 Ultra x RHEON is a pair of trail compression shorts with built-in RHEON polymer elements, a material that stays soft at rest but stiffens dynamically on impact to limit muscle vibration. Decathlon claims an 8.7% reduction in quad vibration compared with the previous model, a modest 140 g weight and an integrated carry belt (250 ml soft flask, nutrition, phone, keys). RHEON itself has already proven its worth on a pair of Kiprun tights from the same range, but these trail shorts are too new for any long-term field feedback.
In mid-August 2026, Decathlon announced a major update to its Kiprun trail range: two new high-end shoes (Kipclimb Max and Kipsummit Max) and several new apparel pieces, including these Trail Run 900 Ultra x RHEON shorts. The idea is to build in RHEON polymer elements. The material comes from a London company specializing in next-generation materials for movement and protection, and it has featured on a pair of Kiprun tights (the Run Compress 900 RHEON) since late 2025. RHEON stays supple during everyday movement but stiffens dynamically in response to impact, which should deliver support that adapts in real time to what your body needs.
For these new shorts, Decathlon claims a lab-measured 8.7% reduction in quad vibration compared with the previous Run 900 Ultra (without RHEON). They weigh 140 g in size M and feature an integrated carry belt with a soft flask pocket (250 ml), a nutrition pocket, a phone pocket and a key pocket: four pockets in all.
| Feature | Value |
|---|---|
| Brand | Kiprun (Decathlon) |
| Model | Trail Run 900 Ultra x RHEON |
| Release | Mid-August 2026 |
| Weight | 140 g (size M) |
| Technology | RHEON polymer, claimed 8.7% reduction in quad vibration |
| Fit | Compression |
| Storage | 4 pockets (250 ml soft flask, nutrition, phone, keys) |
| Main fabric | 65% polyamide, 35% elastane |
| Waistband | Waistband with drawcord |
| Price | €49.99 |
This is exactly the terrain RHEON targets: limiting vibration and muscle micro-trauma on long descents, which is often where next-day soreness is decided.
With four pockets and an integrated carry belt, these shorts suit anyone who wants to run light, without a pack or separate belt, on mid-length outings.
On the tights built with the same technology, independent field feedback reports a very snug fit that doesn't suit runners with muscular quads. Keep an eye on this: the shorts follow the same compression logic and could fit the same way.
© Decathlon, official photo used for editorial purposes
RunMorph tip: if you're between sizes, go one size up from your usual. On the Run Compress 900 RHEON tights from the same range, an independent tester had to size differently from his usual Decathlon sizing. The same likely applies to these shorts, built on the same very snug compression philosophy.
These Trail Run 900 Ultra x RHEON shorts had been on sale for only a few days when we wrote this review, so no independent field feedback exists yet on this exact product. We're flagging that openly rather than implying hands-on experience that doesn't exist yet. However, an independent tester has documented in detail how the same RHEON technology performs on the Run Compress 900 RHEON tights, released in late 2025 in the same Kiprun range and built with the same patented polymer.
His verdict on the RHEON effect itself is clear and positive. After a mountain run with more than 1,100 m of elevation gain, with no trail-specific preparation, he reports almost no soreness the next day, a result he found surprising given how hard the outing was. In his words, his thighs, pelvis and glutes were spared. On the other hand, the same feedback points to an extremely snug fit that needed several adjustments mid-run, a waist drawcord that's essential to keep the garment from slipping, and sweat wicking around the support elements that could be better. He concludes that the shorts version, then in development at Kiprun, looked set to suit trail running better than the tights he tested.
This gives us a solid basis for judging how well RHEON itself works, but it doesn't replace a dedicated review of the trail shorts, whose cut and RHEON integration likely differ from the tights. We own this uncertainty rather than hide it.
| Criterion | Kiprun x RHEON | Salomon S/Lab Ultra 2in1 |
|---|---|---|
| Approach | Compression with RHEON anti-vibration polymer | 2-in-1 shorts with built-in liner, no targeted compression |
| Weight | 140 g (M) | Lighter, no marked compression effect |
| Storage | 4 pockets, integrated belt | Waistband pockets, more minimalist |
| Positioning | Long distance, lots of climbing | Versatile, all distances |
| Price | €49.99 | Premium segment |
These two products meet different needs. The Kiprun bets on its anti-vibration effect for the most climb-heavy runs, while the Salomon stays more general-purpose and less committed to compression.
As part of a RunMorph trail or ultra-trail plan, these shorts belong on big-climbing runs, where quad fatigue hits hardest. As with any new piece of apparel, try them in training before a goal race, and go one size up from your usual Decathlon sizing if you're unsure.
The Kiprun Trail Run 900 Ultra x RHEON brings to the trail format an anti-vibration technology that has already proven itself on a sister product from the same range, with convincing field feedback on reduced soreness. The price stays very affordable for this level of technology. The main reservation: there's no track record at all for this exact product, on sale for only a few days, and the fit may be very snug, so try it on first. 7.0/10: a promising newcomer on paper and in terms of the technology itself, still to be confirmed through extended use once the product is more widely available.