This is especially the case in front of the canvas are more often exposed to dirt because it was at the very front of the motorcycle. Brake was there some type. Semi-metallic type is very durable, has excellent heat transfer even wear faster.
There is also a type of non-asbestos organic does not sound softer though also tend to be quickly exhausted. Another example is a non-asbestos organic with low metal content has the same advantages with non-asbestos organic but more noisy than the non-asbestos brake linings regular.
The best type of ceramic material with a clean canvas and no sound and does not damage the rotor. However, the price is more expensive than other types canvass.