Ursus Arya G is the first wheelset on Sapim's new flexible PBO spokes

Ursus has launched the Arya G, a 50mm-deep all-road carbon wheelset that's the first production set to use Sapim's new RC-1 fibre spokes. Each spoke is built from 16,000 PBO filaments encased in a UV-resistant outer sheath, weighs 1.9g at 260mm length, and is designed to compress radially to absorb impacts while staying laterally stiff. The complete wheelset is claimed at 1,340g (±40g); the price is €2,500.

PBO — para-phenylene benzobisoxazole, sold textile-side as Zylon — has shown up in cycling spokes before; Spinergy used flexible PBO spokes years ago for weight savings. The RC-1's pitch is different. Ursus and Sapim are framing the spoke as an active part of the wheel rather than a passive tension member: the spokes flex under impact to filter vibration, but resist lateral deflection so the wheel still tracks under hard cornering and acceleration. The spokes are round at 2.2mm and use specialised ~5.5mm nipples that true like normal but require slightly larger rim holes.BikeRumorBikeRadar Gravel

The Arya G isn't an existing wheel with new spokes bolted in. Ursus has built the rim and hub specifically around the RC-1: the carbon rim is 50mm deep, 25mm internal and 31mm external, with a mini-hook bead seat that keeps the rim compatible with both clincher and tubeless tyres. Lacing is straight-pull, 21 spokes front and rear, in a 2:1 'Y-star' pattern at the rear running into the U-RG60 hubset. The hubs use Center Lock disc mounts and are available with HG, XDR, Campagnolo/Ekar and Microspline freehub bodies. BikeRadar weighed a test pair at 1,355g (625g front, 730g rear) including tubeless rim tape — within the claimed ±40g tolerance.BikeRumorBikeRadar Gravel

Ursus's headline claim is a 79.67% lab vibration reduction compared to its own Proxima R 50 mid-range carbon road wheel — measured on asphalt and uneven surfaces, not against a contemporary all-road rival, so the figure is best read as 'bigger compliance gain than a typical mid-range road hoop' rather than a like-for-like comparison. The wheel's competitive debut was Paris-Roubaix under Team Picnic-PostNL. John Degenkolb said he 'immediately felt that sense of stability and reactivity' on the cobble recon rides during Spring Classics prep. Team R&D lead Piet Rooijakkers said the wheels 'allow us to tackle mixed surfaces at full intensity while keeping reactivity completely intact.'BikeRumorBikeRadar Gravel

The Arya G50 is on sale now at €2,500. That's mid-pack pricing for a 50mm carbon all-road wheel, and the interesting question is whether Sapim's RC-1 starts showing up in other brands' builds — the spokes are the differentiator, and Ursus is just the first wheel-builder to design around them.BikeRumorBikeRadar Gravel