Citar:This is where those two letter designation come. The chase test is assigned to add a two letter code that we often see on brake pads. EE, FF, GG, HH. Those letters specify the coefficient of friction when a 1" square piece of friction material is subjected to varying conditions of load, temperature, pressure and rubbing speeds on a chase machine.

The first letter refers to the normal friction coefficient. The second letter refers to the hot friction coefficient based on the fade and recovery test. Brake fade is when you notice brake power is less efficient. Recovery is where your pads are cooling down again.

H has the highest coefficient of friction. (superior braking power)

The friction coefficient codes are as follows:

C = < d =" 0.15" e =" 0.25" f =" 0.35" g =" 0.45" h =" "> 0.55

Now you would think that HH is all you need. Wrong. H might be braking to much if you're only commuting.Racing pads might never reach to the right working temperature... It's pretty much up to you which brake pad is best for you.