Originally Posted by
dksix
Can everything but weight be equal now? Last I considered a disc road bike price was very different between disc and caliper brakes. I'd be surprised to be able to buy a both an Ultegra caliper and Ultegra disc bikes for the same price. I would have expect that to be upwards of a $500 difference.
Disc-specific rims aren't terribly common (because R&D is expensive) but these are more aerodynamic, lighter, and stronger than rims with a brake track. Mostly because they don't have to be built around the constraint of having to resist clamping force and extremely high temperatures, instead they can just be built to function as rims.
Enve's 4.5 disc rims are 30/40 g lighter than their 4.5 rims with brake tracks (even though the disc rims are wider), and save ~5w at 15* presumably at ~25 mph. Now 5 watts isn't huge, but it's something.