Here is another maintenance tip from Global Cycling Network. It's good to make sure that your bike's ball bearing hub is in working condition and a regular overhaul is very helpful.
If you have a Shimano wheels, just follow the steps in the video to service your wheels since all Shimano hubs run on cup and cone bearings. Perform this once or twice a year for better results.
Here are the tools that you will need for this job:
Cone spanners (13 and 17mm spanners for the hub)
Degreaser to clean the bearings and races
A tool to get the bearings out
A container to keep the bearings in whilst you clean the hub
Be careful not to put degreaser in the rear hub, you don't like to degrease the freehub. Do not over tighten the cones when rebuilding the hub this will increase friction if it is overtightened.