robatsu

In the midst of rehabbing some components, I've observed that nearly all pitted, etc, loose ball hubs/bottom brackets that I've come across give some evidence of neglected maintenance or careless usage.

So that got me wondering about what is the service life expectancy of loose bearing hubs/bottom brackets (and headsets, I guess, but those are a bit of different animal) given proper maintenance, adjustment? I'm especially wondering about top end stuff like old Campy Record - I have some hubs that have been in fairly continuous service for 20 years now, I'm sort of wondering if the cups/cones will ever wear out.

mcgreivey

It really depends on maintenance, and the riding habits of the bike's owner. Everything eventually wears out, but if the bearings are properly maintained (repacked regularly, and kept properly adjusted), and if the bike is stored properly, the bearings should last a good long time.

cudak888 

If properly maintained, probably not in our lifetime.

Even if the raceway edges wear down over time (I'm taking thousands of an inch here), a maintained BB should not have any ill results emerging from it - any resulting play would simply require a slight adjustment of the left-hand cup. At worst, bearing replacement.

-Kurt

DiegoFrogs

I think the only exception to what others have said here is the absolute lowest quality bearings. But these, too, tend to suffer from maintenance or OEM installation issues.

I've never had a bearing that, when I found the cups and cones to be in good condition, has ever been a problem after I repacked them. I've also never had a problem with a modern cartridge bearing, either.

Road Fan

With frequent enough overhaul, life should be essentially infinite.

Here's a thought, maybe worth a new thread: Should balls be softer than the races, for vintage and rare bearing parts in excellent condition? I'd like some sense that wear due to contamination will be focused on replaceable balls rather than irreplaceable races. If so, we should not be buying high-grade (perhaps 100 or lower) balls, or at least not stainless ones.

randyjawa 

Hard surfaces, polished to some engineering specification, are the way to go. In theory, a properly maintained and adjusted ball bearing set will never wear out, provided it is used in accordance with engineering recommendations. Proper maintenance means, at the very least, proper lubrication. A the balls, in a properly lubricated, ball bearing assembly, will never touch either cup or cone. There will always be a film or grease separating the two.

Lack of use will damage bearing assemblies. With the passing of time, the thin film of grease will be pushed out of the space between cup/cones and balls. Once the film of protection is gone, metal to metal contact occurs and ionization begins. That, too, will toast a bearing assembly.

Short answer to how long will a bearing assembly last - a few minutes if adjusted too tightly and forever is maintained and used properly.

Road Fan

The ionization must be due to long-term contact between dissimilar metals that occupy different positions on the electrochemical scale. To eliminate this we'd want the balls and the races to be made of the same steel alloy.

randyjawa 

Or, one could just ride the bicycle, now and again.