Sorting good BBs from bad?

[alexnharvey]

I recently rebuilt a hub and was surprised to find an occasional rough spot when spun and correctly adjusted.

Then i remembered a moment of uncertainty when a new ball dropped onto the bench with the old and I was confused as to which was which, picked up the one I thought and went on, foolishly in retrospect. The old balls had been running on a heavily scarred cone, so I suspect they have damage.

If I remove all the balls, degrease and inspect them, do I have any chance of finding the bad one amongst the good? I have a loupe, maybe 10x. Am I cursed to discard all the balls and start over? (I.e. Put them in a box into technology advances sufficiently to resolve this dilemma!)

[cycle tramp]

There is an alternative which is to use the hub as you have already built it for the next few hundred miles and see, if through use the rough spot will wear itself out - if it does then I would simply clean the hub again and refresh with new grease..

Ages ago I re-built a set of pedals with their original ball bearings - which were very rough.. however I also built a grease port in each one, with fresh grease injected into them every few months and plenty of use, they are now the smoothest set of pedals I have....

..as smooth as lava .. as Nick Knowles once said on a shreddies advert.... Good God, what was that man thinking?

[Carlton green]

Ball bearings, even reasonably good ones (when a shop doesn’t rip you off) are relatively cheap. Buy a new set, discard the old, and be sure that you aren’t damaging anything. There’s a thread somewhere about the quality that you should be buying for a bike, and it’s usually higher than what they’ll try to sell you in a bike shop.

[jimlews]

There is a "Brucey" post somewhere on here about polishing worn hub bearing cups.

[rareposter]

Am I cursed to discard all the balls and start over? (I.e. Put them in a box into technology advances sufficiently to resolve this dilemma!)

It'll be less effort to pull the old balls out, bin them and put a batch of new ones in than it is to start degreasing them, going through to find the "bad" one and replacing one.

It's always best practice to replace them all in one go.

There's little benefit to keeping old ball bearings unless you need ammo for a catapult.

[rogerzilla]

...or cake decorations for someone you don't like.

[alexnharvey]

...or cake decorations for someone you don't like.

Ooh that's evil.

I decided to run the wheel for a few days and then take it out of the frame and see how it feels. If it's no better then I'll strip it down and inspect the cones before rebuilding with fresh balls.

[Brucey]

BBs are characterised by their size (range) and their sphericty. Weldtite balls are 'cycle quality' and are said to be Grade 500 ie. pretty lousy. Shimano balls are believed to be gr. 25, which is quite good, although not as good as campag balls which are better again. The best balls you can easily buy (eg. at a bearing factors) are gr.10. Whilst it is probably overkill to rebuild everything with these balls it probably makes good sense in other cases, and it probably doesn't ever do any real harm. By contrast if you try and use cheap balls in something good (as I have been foolish enough to do) then you may find that the balls don't share lighter loads at all well, with the three largest balls doing the bulk of the work. The end result is usually a rough bearing which does not last well.

In many 'traditional' cycle bearing designs the load is borne by relatively few balls of large size, running in relatively flexible pressed steel races. This both allows better load-sharing should the need arise, as well as reducing the need for it at the same time. Typically when these bearings are 'improved', stiffer parts are used, perhaps leading to worse load sharing and reduced tolerance to 'cycle quality' balls.

By contrast most cartridge bearings use more smaller balls. These bearings typically rely on load sharing between three or more balls, without which the service loads cannot be accommodated.

The very best cycle bearings are built in the traditional way but use very accurately matched balls, running in precision-ground races of high stiffness. Because of the accuracy, load sharing is usually very good. IMHO hubs which use DFC converted cartridge bearings may offer the best of both worlds.

FWIW I didn't throw any balls out for years; eventually ending up with a big pot full of them. One afternoon, I went through the 1/4" ones, using a micrometer to assess them for exact size/sphericity. IIRC I wound up with a load of balls I was happy to use in the gashest of hubs, my measurements being on a par with those that produce gr. 500 balls. I must have saved at least 50p in the process.....

[Carlton green]

For what it’s worth this earlier thread talked of ball bearing grades used in bikes. viewtopic.php?p=1749734#p1749734

As a minimum use G100 and seek to use better (the smaller the number after the G the better the quality).

Loose steel balls are available from SJS Cycles: https://www.sjscycles.co.uk/search/?ter ... +ascending

[alexnharvey]

I took the wheel out after three trips, about 45 miles. No rough spots could be felt so i haven't stripped it down.

The bearings are Grade 25 from a large bottle i bought in bulk about ten years ago. I reckon there's only enough bearings left to do one more hub.