[marcusarmstrong]

On a disc brake bike, calipers are ~100g, rotors ~120g, and then you’ve got ~150g of tubing/fluid. They’re certainly heavier, but the components don’t even add up to 1000g, nevermind when you offset the rim brake component weights.

[gomox]

And the frame reinforcements for caliper mounts, the extra spokes, the disc compatible hubs, the thru axles, the heavier brake levers, and probably some stuff I'm missing.

No need to get emotional over this stuff, I love my hydraulic discs but they are heavier at comparable price points. It's also not particularly important to have a bike weigh a bit more, I was just letting the OC know that he was wrong on that aspect.

[marcusarmstrong]

Rim brakes need frame reinforcement at their mount points too, albeit not adapters, so that’s 20g. Hubs are 20g heavier each… I wouldn’t really go for a 20 spoke wheel myself but if you did I suppose that would save 20g. 50g for thru axles. 120g on the brifters.

So to add it all up you’re looking at 770g in components/additions, offset by 75g skewers, 310g calipers, and an added 25g or so per rim for the brake track. So discs are naively something like +335g. I obviously agree it’s a heavier system, but I don’t think ballparking the penalty as triple what it actually is is reasonable.