Originally Posted by fjyang
Hydrolics are more powerfull becasue they can exert more pressure per square inch than what our hands can pull with cables. Its like power assit steering and brakes with cars. Have you ever try to steer your car with the engines off?
Fjyang, this assertion is incorrect. A cable or fluid line only tramsmits power. It is true that you can do some interesting things with hydraulics. For example, it's a lot easier to distribute load over multiple pistons. You'll never see a cable pull brake with more then one piston. Hydraulics also do provide a convenient way to express mechanical leverage. In the end however, this is no different then what the throw lever on a mechanical screw piston provides.
People make analogies to cars and they are WAAAAY off base. It is the engine that provides the power assist on power brakes. The fact that the system is hydraulic provides no "extra power" even though the system relies on the hydraulics for it's operation. This does not translate into bicycle brakes being more powerful because they are hydraulic.
Rotor/caliper diameter, rotor material, pad material, mechanical leverage, calibration ... these are the factors that will determine how much braking force you get from a given input on the lever. There is no "power assist". A hydraulic system once setup will remain in calibration as it is self adjusting. Beyond that there is no "power advantage" to a hydraulic over a cable based brake system.
If a Juicy 7 way the same price as a BB-7, I'd have Juicy 7s. Since they are more expensive, I'm content to turn the little dials every couple weeks.