Bearing are normally left far to long before they are serviced and come out as a rusty mess. Most bearings aren't sealed and most grease's don't have a great ability to repel water. The photo's below show what happens when water gets mixed in with the grease.
The ball bearing are all pitted
Finally headset bearing come in for a tough time especially the bottom one by the wheel
Again regular servicing could eliminate this kind of damage
If you've got any questions about Cycle Repairs then please contact us on either 07812 033 064, 01446 796 959 or via the Online Quotes and Booking Form on the website or by email at peter@valecycleservicing.co.uk