Originally Posted by
SpedFast
I like disc brakes and have them on my MTB. But my rim brakes will lock up both tires just as well on my road bikes. So with the tires locked up on my MTB I can stop in half the distance that I would be able to if I lock my tires up on the rim brake bikes? Brakes are brakes. If they'll lock up the wheels the stopping distance is going to be the same. Or am I missing something here?

Edit-The main thing I like about disc brakes is that I won't have to replace the rims because they're worn thin.

The difference between rim & disc isn't about exceeding the friction of the tires contact patch; the logical limiting factor of all braking systems. It is about
how you get to that point.
Imagine having all the progressive power modulation of a short pull lever on a long pull "V" brake with none of the fiddly setup or pad travel concerns of mix-n-match pull ratio system...That is the nut hydraulic disc seeks to crack.
More force for less effort and a more progressive predictable path to get there makes for an improved, more forgiving rider experience.