Originally Posted by
Kapusta
Maybe not well articulated, but Alo is basically correct (if I am reading him correctly).
On rim brakes, since the brake pads need to cover more distance before hitting the rim, the mechanical advantage of the lever over the pads needs to be less less (so that more pad travel distance can be covered as you pull the lever).
Part of the reason that disc allows more mechanical advantage of the levers over the pads is that the pads can be set up very close to the rotor, so you can set up the system with the lever having more mechanical advantage over the pads without spending a whole bunch of lever throw just reaching the rotor.
Not sure If I explained that any better, but there you go.
There is nothing that limits a rim brake from being set up close to the rim. Again, if the rim wobbles, that’s something that can, and should, be fixed. I’ve run my brakes so that the wheel is locked at about half travel of the lever which is similar to how hub mounted discs have to be set up. I currently have bikes with hub mounted discs, dual pivot rim brakes, mixed front disc/rear linear and
cantilevers...Oh! The humanity! The cantilevers are actually on the bike that requires the most braking power...a loaded touring bike. I’ve even ridden that one down New Found Gap in North Carolina in a driving rain at around 50mph. I had no problem slowing nor stopping.