Replacement bearings
 

Hello all, when restoring, does anyone have suggestions on quality of replacement bearings? I am sure the re is a variety of quality but how to chose what is best????


DB

Grade 25 is all you need for a bicycle and are at a good price point.

If they are loose ball type, and not a cartridge sealed bearing, @easyupbug is spot on, IMHO. Take caution though, even doing the Grade 25 can get silly in their prices, if you are looking to stay with NOS/NIB Campagnolo bearings though. Lots of listings for loose balls on-line, at eBay, and you can find them at a home improvement box, or hardware store as well, in the various necessary sizes. Just exercise due diligence about low ball offerings and the big bulk sales, these can be iffy in their quality and consistency.

Bill

For bearings I just go down to my LBS and get a package of "enough plus a few" for, I dunno', maybe $5.

Problem with that is that you are not supposed to mix production lots of bearings. You end up with small qtys of unusable bearings.
I order the Wheels bottles of bearings, mostly from Amazon.

I doubt anyone except the vendor upstream knows, and even then, it's unlikely you'd talk to the right person. To compound the issue, you will almost certainly not be able to find out/know the hardness of the cones or races for the system you're putting them in. IMO, hardness (at least as it pertains to bicycles) is not an issue, if you're buying quality (grade 25) bearings. Grade DOES refer to quality, after all. Yes, it doesn't denote hardness specifications, but (again) my experience is that it isn't really necessary to seek out that info for bicycles.

Boca Bearings is a great choice, and you can even get Si-N ceramic balls there if you want to reduce your mass.
I'm running them in my C-Record hubs.

He! Then you end up with a large quantity of unused bearings, usable or not.

If I'm rebuilding a BB, I get a "tub" of 25 1/4" balls, use 22 or 24 of them (can't remember it it's 11 or 12 per side!), then keep the rest for some unknown purpose. The smaller balls come in packages of more which is good because I need more. I will invariably drop one or two anyway. :eek: In any case, it's not like they cost large bank deposits. Bearings are cheap!

Hmm, how's to know? OTOH, one time when I rebuilt a BB in our tandem I found two of the bearings looked like the moons of mars, highly disfigured and, shall we say, not quite complete spheres. Surface hardness may or may not have been a factor. Fortunately the races were okay.

That might suggest that the original bearings weren't of the best quality or that the lubricant layer had broken down in some way. They're subjected to quite high loadings in use.
If the bearing isn't as spherical as it should be or the grease layer fails, then they will quickly mash themselves up and turn very ugly. They don't tend to overheat like a car wheel bearing might do, but they still seem to make quite a mess of themselves.

Actually, for bearing manufacturers, bicycle applications are about as easy as they get. Low speeds, no temperature extremes, and light-to-moderate loading (compared to other applications), used only for short periods of time on an occassional basis, and typically not subjected to severe environmental conditions. Even low-quality bearings will last for a fairly good while, though eventually they will fail as fidbloke pointed out in response to jimmullers observations. If the surface hardening isn't deep enough, for example, the loading will impinge through the surface hardness. I've seen the surface flake off of bearings.

Good quality Grade 25 bearings should last a long time if preloaded properly and lubed properly. There's no need to stick to only one production run either, mixing different production runs isn't a problem--we're not running them in gyroscopes....

A common bearing made today by a reputable bearing manufacturer will perform far better than most bearings made up through World War 2, manufacturing processes have improved that significantly. Of course, there's still low-quality or counterfeit bearings out there which can fail miserably.

One barometer of quality I use for caged headset bearings is bearing count. Quality sets like Tange Levin incorporate 20 balls or more per cage for a 1" set. I've seen cheap headsets with 12 balls per cage in them.

Send them to me, and I'll test them on the Rockwell Hardness Tester I have in my lab......

Actually, even without a Rockwell test, there are small pocket scratch testers.

I've laid in a stash of vintage Campagnolo caged bearings and loose balls.
I think they're superior to modern bearing balls.

Yes, I'm capable of believing crap like that.

What makes you think whomever fills those bottles for Wheels (undoubtedly just private labelled for them) is actually doing that? They are probably not even counted and filled by weight. Unless some purchaser requires documentation of lots/heats/production runs it doesn't happen in the real world and will be charged for accordingly if required. Certainly not for low speed/torque/loading/tolerance applications such as bicycles.

grade actually just refers to the tolerance for "sphericity" or roundness in all dimensions, grade 25 is spherical to within 0.000025 of an inch. Also the grading specifies the roughness of surface finish, so grade 25 have a "Ra" number of 2.0 or better, where lower grade (which have a higher grade number such as grade 100) will be rougher as well as less perfectly spherical e.g. grade 100 have a Ra of 5.0 or better.
I've only ever seen and bought grade 25 balls that were made of chrome-alloy steel but the material of the ball is not necessarily grade-specific.

And that is an important factor these days I would think.
How good of steel alloy was used in some of the grade 25
bearing balls offered by some vendors these days? Who's to know.

That's why I like old Campy balls and bearings. They were made with great steel,
I think. Though I have no empirical evidence to support that. But having pulled many out of
thirty to fifty year old bikes to find them looking like new, convinced me.

The critical stresses on the balls will be higher than on the races, due to the balls' smaller net radius. Hence, everything being equal (e.g. hardness), the balls would exhibit fatigue failure first (flaking of the surface). For maximum time between overhauls, there is a case then, for making the balls even harder than the races.

I've seen some cases of the balls failing in fatigue, but most of the messed up bearings (at least good quality ones) I've seen, have been messed up due to lack of lube, or water contamination, or both.
The only races I've seen with fatigue issues are hub cones of the Normandy/Atom variety; and this seems to be pretty consistent in my experience, and reading on this forum.

So as a PSA, if you have any french hubs with miles on them that you haven't checked, take a look, and be prepared for an overhaul with new cones (and new balls as a cheap precaution).
That said, so far, all the french hub cups I've looked at have been fine, for whatever reason.
Hmmn, come to think of it, maybe I should take some of my own advice... :innocent:

Whatever the stated grade of bearing, it pays to know the manufacturer and origin of the bearing. Under no circumstances will I use Chinese bearings in any bike part that I value at all. The quality control is just too poor.

Interesting thread here on mixing bearings.
http://www.bikeforums.net/bicycle-me...-bearings.html

I'd have to admit, with the poor finish on bike hub races and cones and the usually crappy preload tolerances/adjustments, I'd think mixing bearing production lots isn't something to worry much about.

I wonder how one finds non-Chinese or Indian made bearing balls?
There are still USA companies making balls, but vendors seldom list where they sourced theirs from.

I have a fair stash of SKF balls that I put together some years ago that have me in good shape for the future....but it's a good question..

Very true. You can never trust grading of anything coming out of China. Since a good micrometer only measures to .0001", you would be hard put to tell if you were truly getting real grade 25 loose balls and who knows what alloy they would be. To make matters more confusing, bearing assemblies are graded differently than loose balls. From my understanding, bicycle standards are grade 25 loose and grade 5 for assemblies. I don't know how ceramic bearings are rated.

I think I read somewhere that SKF supplied balls to Campagnolo back when.