Why choose Hydraulic brakes?
There are many reasons to consider hydraulic brakes over mechanical brakes. I'll
cover several issues, the first is cable stretch.
Brake cables do extend and stretch when the brakes are applied, as the housings
also compress. This gives a little more mush feeling at the lever, especially when
using levers with a lot of leverage.
Hydraulic lines also swell and expand under fluid pressure. The effect is exactly
the same as cables stretching, under a lot of pressure you can feel and even see
the hoses swelling. On both cable and hydraulic brakes there is always a slight
difference in feel between front and back brakes, the front feels a little crisper.
The second issue is friction.
Friction exists in all systems, in a cable system it's friction between the liner
and the brake wire, in a hydraulic system it's between the fluid particles as they
move up and down the hose. The major difference is mechanical friction increases
with normal force and hydraulic friction increases with velocity.
On a mechanical disc the friction in the cable is greatest when you have the most
force on the lever, where fine control gets hard to find. On a hydraulic system
the most friction is found when the lever is moving the fastest, before braking
has begun, when the most force is on the lever the fluid is not moving and the
friction drops to zero.
Here hydraulic systems have a major advantage, fine control at or near maximum
power. The same advantage also applies in lever return.
This is one of the reasons why there will always be hydraulic brakes, power,
feel and fine control cannot be matched.
On the other side of the coin. Mechanical discs offer a lower cost, but higher maintenance
alternative to those who appreciate the advantages of discs without the hassles of bleeding
or the initial higher price.
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