Baitcaster braking systems
A baitcaster brake slows the spool, not the lure. That matters, because everything else follows from it: the harder the brake, the shorter the cast, and the point of setting it is not to brake more but to brake exactly as much as is needed.
What they actually slow down
On the cast the lure pulls line and spins the spool up. Then the air starts slowing the lure — but not the spool, which has momentum of its own and keeps turning. At that moment line leaves faster than the lure takes it, and gathers into loops.
So the brake has one job: to stop the spool outrunning the lure. That is the backlash the entry on baitcasting reels describes — the brake simply prevents it from forming.
A centrifugal brake works at the start
Small blocks sit on pins inside the spool. As the spool spins up, rotation throws the blocks outward and they begin to rub against a ring in the sideplate. The faster the spool turns, the harder they press.
Hence its character: it brakes hardest in the first fraction of a second, while the spool is accelerating, and has almost let go by the end of the flight. It is adjusted mechanically, by switching individual blocks in and out.
A magnetic brake works evenly
Here it is not friction that brakes but magnets: they induce currents in the metal spool that in turn resist its rotation. That force also grows with speed, but it acts throughout the whole flight rather than only during the spin-up.
The adjustment is external — the magnets are moved towards the spool and away from it, often with a dial on the sideplate. That is more convenient: the setting can be changed without opening the reel.
Why both are often fitted
Because they cover different parts of the cast. The centrifugal brake takes the surplus off the spin-up; the magnetic one keeps the spool steady all the way to touchdown. A reel with both lets you set the beginning and the end separately.
The spool tension knob is a different thing
The knob on the sideplate under the handle is not a brake in this sense. It takes the end play out of the spool shaft, and it is turned before the brakes are set, not instead of them. The order is in the entry on setting up a baitcaster.
No brake replaces your thumb
No brake knows that a crosswind is about to catch the lure or that the water is now close. Your hand knows: the thumb rests on the spool and feathers it in two places — at the top of the arc and just before the lure lands.
That is why a baitcaster has to be learned. A brake lowers the cost of a mistake; it does not remove the action itself.
What we do not state here
How many blocks to switch on and where to set the magnetic dial. That depends on the particular reel, the weight of the lure and the wind all at once, and no general number exists — the ones that circulate in advice are usually taken off somebody else's tackle.