That’s a square-oval shaped, 42mm rim – a squoval – developed by Hed with Cervelo.
In the wind tunnel, air reportedly “whips right over the squoval” v. wedge shapes …
On test now with reports to follow.
Specs are 721g front and 870g rear. Details from Hed:
The idea of the squoval shape is twofold - to first let crosswinds come off the nose more cleanly. They are almost unaffected by crosswinds. Second, while the pointy nose is good at the front of the wheel (air hits the wide part of the wheel and then flows back to the skinniest section), at the other end of the wheel, a pointy rim just turns the airflow into a wedge. The wedge flow keeps going wider when it comes off the wheel for some distance before is starts to suck back in behind the tire.
With a more blunt leading edge like on the squoval,the air gets split wide early, and as it travels across the wheel surface it comes back closer and closer to the surface and then comes off the tire more cleanly.
Possibly perceptual – like getting your kid a new pair of shoes and they run way faster – but the C2 effect feels more pronounced with the 42s. The ride really felt supple and responsive, more like a tubular than the Ardennes or wide Jet 60s. That’s seems like a contrast to say a wheel is “stiff, fast, and quick” while not harsh or like a pogostick, but that’s what this wheel does.
For more on the C2 effect and that platform, see our review here, when we rode the first prototytpe. The C2 is a 23mm wide rim that changes the tire profile:
when the tire spreads on the wider rim the sidewalls flatten and that reduces their springiness ” that results in the tubular feel.
The 42s do not sound like Heds normally sound – Heds have a very distinctive, whoosh, whoosh sound. Maybe that’s what a "hedervelo" sounds like instead?
Also, I really appreciate how "tight" the bearings are. I understand the no-hub preload in the front or hub-preload-in-the-skewer in the rear, but my Ardennes (and other wheels like Reynolds) move 3 - 5 mm, under load. These barely budge.
Also, the Roleur effect of these wheels seems more pronounced. Get them up to speed, they roll, and yes with much less movement from sidewinds. It’s possible the less movement sideways means more forward momentum.