The freewheels on our most recent hubs are based on a ratchet system (36T, 40T and 48T). Previous wheelsets used either 3, 4 or 6 pawl and spring system. Both designs are found on many high end hubs and wheels. They might be noisier than some other hubs but this is generally regarded as a sign of good engineering.
This is the sound of positive engagement of the ratchet(s) or pawls in the hub shell. With our ratchet hubs, the sound is from the ratchets engaging when you freewheel (coast).
Our previous pawl and spring hubs are individually sprung using a strong leaf spring, which connects with one of the 45 ratchet points in the hub. Not only that, they engage at several points resulting in very strong engagement.
These are a similar design to those used by companies such as DT Swiss, Hope, Royce, Tune, Zipp – all companies renowned for the engineering excellence.
This can be quietened down, depending on your system, by adding a low friction grease onto the ratchet ring in the hub shell, or to the ratchets in your freehub body. This will deaden the vibration and quieten the hub, but please note if you add too much grease or use thick grease this can cause the pawls to not engage as well.