Photos:
Super wide with short shoulders and lips. I found it really easy to install a tire.
Reinforced spoke holes with a 3mm offset to improve spoke tension balance. Nice!
Detail on the spoke hole reinforcement.
Comparing the HR942C to the Stan's NoTubes ZTR Flow rims. I think the flow could fit
inside the carbon rim!
Weights - surprisingly light for how wide - I'll make the lighter one the front.
Okay, now - how much of a difference does rim width make? Let's find out. I had a Kenda Small Block Eight 29x2.2 tire on hand, mounted up on the Bontrager Duster wheelset that came stock on my Trek Rumblefish. Measuring the tire when inflated to ~30psi:
Moving the tire to a Stan's NoTubes ZTR Flow rim: Yes, wider, but not even a full 1mm wider.
Moving the tire to the HR942C rim: Ignore the tilt (and the out of focus) on the calipers, I did the measurement and am holding the camera and calipers in a precarious balance. Surprising - all that extra rim width and only 4mm wider at the tire.
I also had a Schwalbe Racing Ralph 29x2.4 on hand, so I mounted that up, and it's starting to look seriously big, not quite 29+ range, but comparing it to a 29x2.2 on a race rim: That's a full 62.9mm wide, 2.475"!
Next is ordering spokes and hubs.