The brakes are divided into brakes more suitable for downhill uses and brakes more suitable for less demanding uses (cross country). Nowadays, however, also the discipline of cross country, at high levels, needs top-of-the-line products, given the increasingly demanding routes and increasingly high-performance bikes. So sometimes the 2 worlds mix, with products that can be used both in cross country what an enduro.
2 PISTONS AND 4 PISTONS BRAKES
A rough subdivision of the brakes can be made by dividing the 2-piston brakes from the 4-piston ones. Calipers with 2 pistons (1 on each side of the disc) are simpler, more compact, safer and lighter. Calipers with 4 pistons distribute the effort over a larger surface area of the pad and are more powerful. Until some time ago, in general, it was like this and we found 4 pistons in the Enduro/DH segment while 2 pistons in the XC/Trail sector but now, for example, we find brands that produce gravity brakes with 2 pistons increased therefore this rule is no longer law.
ADVANTAGES 2 PISTONS BRAKES
Smaller pads: the advantage of a smaller pad is the lower weight, as well as the fact of having less material in the caliper (also saving precious weight). Maintenance is easier, especially if you have piston problems (2 pistons 2 problems, 4 pistons 4 problems).
ADVANTAGES 4 PISTONS BRAKES
Larger pads: braking on a larger surface leads to greater friction (more powerful braking) and as there is more wear material it takes longer for it to wear out.
What is more complicated is the cleaning the pistons. In four-piston brakes it is in fact easier for one piston to get lazy and not work like the others.
As regards the modularity of the brake, in general the 4 pistons are more modular but it is not a fact because it then depends on how the lever was developed and therefore on its leverage ratio (excuse the pun). ATTENTION: Less modulable brake does not mean less powerful. And the feeling on the lever can also depend on the oil used (whether mineral or DOT): you can learn more about the topic at this link.
BCA'S THOUGHT
I had a motto which was: two pistons, two problems, four pistons, four problems – Andrea Brioschi, High Tech BCA Performance
PROJECTED IMPACT
As you have read, there is no definitive answer because the basic concept can then be changed. The basic concept is that a 4-piston brake is more powerful and modular while the 2-piston one is lighter and simpler to maintain. This is why the 4 pistons are recommended for gravity disciplines while the 2 pistons are recommended cross country/between. The braking power can be the same between 2 pistons and 4 pistons, at most the 2 piston will be less modulable than the 4 piston counterpart however BCA, for example, has overcome this problem by using 2 larger pistons and using DOT oil. This is why we must then carefully evaluate product by product and not stop at appearances.
