Originally Posted by
Dave Mayer
Yes, perspective... Most new road cyclists come from a MTB background, so 18 pounds is feathery. Coming from a road background, 18 pounds is heavy – uncompetitive heavy. I suppose bike weight doesn’t matter that much if you’re cruising to the coffee shop, but when you are suffering with the fast crowd, bike weight, particularly wheel weight is critical. If you lose contact with the wheel in front of you accelerating out of a corner, or up a climb, you’re toast: suffering far more for miles solo trying to catch up.
Why do disc-compatible wheels weight so much? On disc wheels, braking forces are transmitted from the ground through the spokes to the rotors/calipers then through the fork and then to the rest of the mass on the bike.
In contrast, on rim brake wheels, forces are transmitted from the ground circumferentially through the rim to the brake calipers. And from there to the fork crown to the rest of the bike. Forces transmitted through the fork and spokes are much lower, which means they both can be built lighter.
BTW: the need to bulk up the fork and frame to handle disc-generated forces is a key reason why these are so harsh and dead feeling. I suppose this is a motivation for fatter tires, which then further adds a bunch of weight and rolling resistance.
Rim-brake specific wheel rims are in fact heavier for obvious reasons, but the hubs are lighter. Overall wheel weight is usually within a few grams. Lighter wheel rims are more efficient, so that's a win for disc-specific wheels.
A stiffer fork does not make a bike "harsh and dead feeling". Not to mention those are contradictory qualities.
Your statement about most new road cyclists coming from an MTB background is absurd!