The hub is actually very simple, but all hubs are nothing more than a rolling friction roller, not the main body shell, shaft, fasteners (nuts or quick-release levers), and the three bitter enemies must each other for life. 

1. Ordinary single speed hub
The most common type that can be replaced with a flywheel is generally made of iron, loose beads, and some have bead nests.

2. One fly single speed hub
Relative to the high-end commuter bike, it has a tower base structure and the flywheel can be replaced separately. Generally 14 teeth.

3. Internally geared hub
Commuter cars generally use internal three-speed hubs.

4. Inverted drum brake hub
It has a rear hub that drives the brake mechanism when the chain rotates in the reverse direction.

How about this carbon fiber mountain hardtail bike from the picture? Isn’t it handsome? Do you want to build one for yourself? The following is the assembly list of one of our customers. The cost of the whole vehicle is about $2000.
Frame - Trifox Carbon MTB Frame MFM200
Groupset- deore xt-m8120 4piston.
Seatpost - profile design 
Saddle - fizik
Hubs - fastace
Disk - shimano icetech
Handlebar - syncros
Fork - tfsa carbon
Mavic crossride -wS
XC folding tires
Deore xt standard BB

The various rolling bearings used in bicycles (mainly hubs, bottom brackets, headsets, pedals) can be simply divided into bearing and ball gear bearings.

So what exactly are bearing shaft and ball gear bearing?

The bearing shaft actually refers to a shaft that uses an industrial deep groove ball bearing assembly as a rolling bearing. The structure can be seen in the figure below. Its characteristic is that it can be repaired by replacing the bearing assembly when damaged.

The ball gear bearing is composed of a bowl, a shaft gear, and a ball in the middle. They and the hub body together form a large bearing. Because the ball does not need to use a cage-like industrial bearing, the ball gear structure bearing of the same size can accommodate more More balls, and each ball has a larger contact area, which can withstand greater pressure.

All Trifox carbon fiber road bike wheelset RW100 Series are use bearing hub.

I don’t know if you have any experience like this, that is, the riders around you are pursuing a very loud hub. For example, the pursuit of a lot of 120-sound hubs does not mean that the louder the hubs, the better.