Sealed bearings
 

Are they really a no maintenance item?

Yes, there aren't and are. Typically about 5 yrs live on these depending on usage...I'd PM Rev. Chuck on this one WK. You bum...
:)

My cdale hub was about shot.. lots of gray matter in the little grease remaining. So I went through and ****ed up all the hubs laying around.. and it dawned on me that it was a pita, and perhaps sealed bearings would be the way to go..

Do you mean cartridge?

Per Sheldon:

A "sealed" bearing is one which has rubber or plastic gaskets to prevent the entry of dirt. In the bicycle industry, the term "sealed bearing" is often used colloquially to refer to a cartridge bearing. This can be confusing to a consumer who may think that a hub is a high-tech cartridge-bearing unit, when it is actually a normal cup-and-cone bearing with a plastic dust cap.

My Suzue's (among others) have "sealed" stamped on the cap, but they are cup and cone. My experience has been that properly maintained, sealed (cup n cone) bearings will last a lifetime. This is predicated on the quality of the parts of course.

Even cartridge bearings need maintainance, not as often but they still need service. I just did some work on my friend's bike, I checked his Chris King headset and hubs, the cartridge bearings were dry. His assumption was use them till they need to be pulled and replaced. If you open up sealed cartridge bearings once a year look them over, clean if necessary and add grease they will last a long time.

I have found that some manufacturers under lube their new components. I installed 3 new Shimano headsets on project and friends bikes this year, I had to add grease to each of the sealed bearing cartridges. That just shouldn't be the case. When you turn cartridge bearings you should feel a smooth drag, that tells you they are well greased and that the seals are tight.

The nice thing about cartridge bearings is that when they do go bad you can replace everything in one step.

hmm....more grease, eh? maybe that's what's wrong with my 105 headset...