How Necessary Are Bb30 Bearing Covers?


New Member
Sep 7, 2007
So I removed my crank to clean it, and sure enough, a piece went missing when I was ready to reassemble. It was one of those thin black caps that go over the press fit bearing. I wanted to go ride, so I reassembled everything even without the bearing cover. Is this a problem? Will this be a problem? I didn't notice any issues, but there must be a reason why those bearing covers are there?? Thanks a lot
Sure there is a reason, and that's to exclude as much water, dirt and grit as possible from the bearings. The pressed-in cartridge bearings in your BB don't have much in the way of seals themselves, just the little non-contact seal rings between the races. Not sure why, but the grease inside the bearing seems to be a magnet for dirt and sandy grit. Depending on road conditions where you ride, and if you stay out of the rain, you might be able to get away without the cover for awhile, but I'd say the life of the bearing is going to be much shorter without it.

I've replaced the bearings about 3 times on my Megatech BB over 11 years of use, and each time it's been due to the dirt and grit which got under the seals and made the bearings "notchy". The bad bearings don't really show up when ridiing, but are noticeable when turning the cranks gently with a finger (after dropping the chain off the little ring). Once the crankarms are pulled, it can be difficult to turn the spindle by hand....the notches are that bad.