Originally Posted by Dave Mayer

The Emonda SLR RSL rim frameset weighs 640g. Specs here:

Émonda SLR RSL Frameset - Trek Bikes (CA)

The disc equivalent is 665 g, but the disc fork, because it has to overcome forces at the ends of the blades instead of at the rim brake crown, it has to be considerably bulked up. The relative fork weights are harder to find on the Trek website, for a reason.

Of course, this bulking-up renders the disc brake fork less flexible and less compliant. Perhaps one reason for the irrationally fat tires (>28) being spec'd for road bikes. Because the disc-specific fork absorbs less road buzz, the tires are forced into this role. Plus we all getting fatter.