Just a few weeks after seeing the new Sapim RC-1 spokes at Sea Otter, we’re getting a look at the first wheels to be built with them, along with more information about the spoke itself. The new Ursus Arya G gravel and all-road wheels are built around the new Sapim RC-1 PBO spokes connecting new rims and hubs. The combination debuted at Paris-Roubaix under Team Picnic-PostNL, helping smooth the cobbles thanks to the spokes’ ability to compress and absorb impacts.

What’s PBO? Long before Bikerumor was a twinkle in Tyler’s eye, Spinergy used flexible PBO-fiber spokes to save considerable weight over that era’s “lightweight” wheels. While that brand had its wins and losses in terms of product, the technology behind the spokes was sound and has occasionally been repurposed in the cycling world (and is still used in many lightweight wheelchair wheels).

In contrast to carbon fiber spokes, PBO (Polyphenylene Bensobisoxazole) is a synthetic fiber from Applied Fiber that’s flexible, but not stretchable. Meaning, PBO spokes allow the wheel to compress radially to soak up impacts and vibration, but not flex laterally.

Sapim’s RC-1 spokes are just 1.9g each (260mm length) and are made of 16,000 PBO fiber filaments with a UV-resistant outer sheathing. They use specialized nipples that install and true like normal, but are ~5.5mm thick, requiring the rim to have slightly bigger holes.

The spokes themselves are round, measuring 2.2mm in diameter, making them better suited for rough surface rides where aerodynamics play second fiddle to comfort and traction.

The spokes aren’t just added onto existing parts. Ursus’ OmniTune System (OTS) means a custom build with the straight-pull Ursus U-RG60 hub using their Y-stars (2:1) lacing pattern, going to a 50mm deep, 31mm wide (external) carbon rim. Internal rim width is 25mm.

This combination produced a massive 79.67% vibration reduction (in the lab, claimed) compared to their Proxima R50 model, yet remains agile with sharp handling, even on the chunk. Does it work? Here’s what the team riders have to say:

“From the first moment I rode the Arya G on the cobbles during my recon rides for the Spring Classics, I immediately felt that sense of stability and reactivity, combined with the ability to absorb the harshness of the stones on the hardest sectors. Comfort is performance,” says John Degenkolb, rider for Team Picnic-PostNL.

“Arya G is a truly innovative and fundamental tool for the team, because it allows us to tackle mixed surfaces at full intensity while keeping reactivity completely intact and delivering an exponential increase in comfort,” adds Piet Rooijakkers, Team Picnic-PostNL R&D Expert.

Running 21 spokes front and rear, the complete wheelset weighs 1,340g (±40g). Hubs fit Center Lock discs. MSRP is €2,500 per pair, available with HG, XDR, Campagnolo/Ekar, and Microspline freehub bodies.

Ursus.it

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