Bearings
Bearing
Hubs Bearing Guide
The hub is the central part of your bike's wheels (front and rear), which connects to the wheel's rim via the spokes and through which the axle is fitted, enabling the wheel to freely spin on two sets of bearings.
As bikes have front and rear wheels, so too have they front- and rear-specific hubs. The front hub is simply designed to enable the wheel to spin, while the rear hub is a little more complex as it also forms part of the bike's transmission the cassette or sprocket which drives the rear wheel is attached to the rear hub, which on most bikes also features mechanism to allow you to coast or freewheel (exceptions being fixed-gear or 'fixie' bikes and track bikes).
Your wheels spin more than any other part of your bike. Therefore, having the best bearings in this application is crucial to producing the best results.
A Special Structure
Besides the patch where your tires meet the road, what's the next spinning component that can either slow you down or let you roll faster?
You would be correct if you said hubs, but that component would be more accurately described as the bearings inside.
And if you've put this Hub Bearings ABEC-3 bearings inside, you've just upgraded your hub to another level.