When to replace BB bearings
 

I'm not sure if some of you remember a while ago me asking where to source bearings from. I thought I may need to replace my bb soon and wanted to get a head start. I ended up with some nice NTN bearings I bought from hambini in the UK. I've tried looking around but can't seem to find good advise on how you know when it's time to replace them. I rode through a pretty epic rainstorm, one point being submerged up to my cranks in water. A few weeks later I'm hearing a slight click in my bb now. I pulled my cranks, cleaned everything up and notice that the DS bearing has the inner and outer races rotating. Is that a sign to replace? The NDS side still only spins on the inner race, there is no lateral play on either of them. There is the slightest feeling of roughness when rotating them. These are the stock green shielded FSA bb30 bearings that came with my caad12 that just went over 5000 miles. Am I just being too cheap, and should just throw in the new bearings I have anyway? I've got the proper tools to remove and press in the new bearings already.
Any advice would be appreciated.

The outer race shouldn't turn. You may need to use Loktite to mount the bearing.

Are you suggesting that yes, that is a sign to replace them?

Yeah, movement of the outer race in a press fit assembly is bad as it can wear the press fit interface. While I generally let cartridge bearings run until they feel a little rough, I'd definitely just replace them in your case. 5k is decent mileage (though my BB30 bearings are doing way more than that, but they haven't been bathed in a river either). I would install using a bearing retaining compound in your case.

Agree with cpach. I'll add that if the outer race is spinning within the BB shell that means that the bearing has more friction inside it then outside it. "Do the math." A cartridge bearing in good condition will rarely spin it's outer race, even with a rather sloppy fit. Andy

Thanks for the replies, the main question still stands. How do you know when your bb is worn out? With chains there are guidelines with measurements, chainrings there are guidelines with looks, but I've found none for bb bearings. I'm going to go ahead and replace these based on the comments about the races. I'm looking to know for future reference now.

Generally speaking you should replace them if they make noise, or feel rough. I will generally let them run if there's just barely perceptible amount of bearing feel. Generally the replacement point should be before you notice the friction at the cranks--there's obviously a lot of leverage at that point. Spinning the outer race is a pretty clear sign of both bearing wear and the need for a better interface between the bearing and the shell.

Thanks. Upon closer inspection, I'm a bit of an idiot. It's the green bearing shield that was spinning with the inner race on one side, not the outer race too. Either way that is an indicator of more friction right?

Just did the swap today. It's pretty amazing how much less drag the NTN 6806 LLB bearings feel in your hands vs the FSA 6806 2RS. One of the old ones was absoultly filthy, smelled like stagnent river water. Other one was much cleaner looking but still decently stiff. No grinding though. I'll post pics in a bit for anyone that cares to see.

Oh, well, that's good. Bodes better for your BB shell.