Originally Posted by
cyccommute
If anything the discs are a step down from rim brakes. The hydraulic brakes I have are digital, they are either on or off with no gradation in between. Modulation, as in being able to apply the brakes in a manner using finesse, is nonexistent. A tiny amount of pressure locks the rear up.
Rim brakes, on the other hand, have always given me the ability to apply enough pressure to scrub some speed or lock the wheel with all kinds of modulation between the extremes. This includes the cantilevers I have, the v-brakes and the side pull calipers.
I've found the opposite to be true - My discs modulate beautifully. I think it's a setup (and to some extent make/model) thing.
To be fair, rim brakes can be set up to modulate well, too. For example, I was able to get phenominal modulation from my Avid V-brakes (SD7 ti with the SD 7 levers). My Campy Record dual pivots were excellent, as well.
But to say discs don't modulate well (as a general "truth") is incorrect.