Is a ball a ball ? Bearing question.

MADJEZ

Senior Retro Guru
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Engineering question !

About to take apart some 20 year old Deore hubs to replace the bearings.
I was wondering will any ball bearings do (obviously of the correct size), or do XT, XTR etc have
fancier material ball bearings than the cheaper hubs.
 
Ball sizes are usually standardised. A good overview of common ball sizes is given on this german web site (self explanatory, no need for Google translation):

http://scheunenfun.de/kugelringe-star.htm

There are some differences concerning overall quality and size uniformity between one batch of produced bearing balls. They´re more or less related with - oh wonder - the price.
 
XTR used stainless steel grade 25,
XT probably the same but not sure.
Lower down probably chromed steel not sure of grade.

Stainless has the advantage of not rusting or getting surface damage, you tend to pull them out of old bikes and they are fine and being fine the cups are in better condition.
The chrome steel ones tend to get chunky surface damage (like plate tectonics) this over time has often damaged the bearing surface on the races.

Of course not always either easy and nothing regular clean, dry, regrease would not have prevented.

Either can be used in either of course, though grade 25+ stainless are not the easiest to get hold of. Grade 10 chrome steel are cheaper.
I wouldn't bother with grade 100 or unknown. Mainly as you don't have to, though they would be perfectly fine in a deore hub.
 
Deore hubs wont have bearings or cones as good as XT etc. Obv depending on the background of the hubs they might be Ok or very worn, If the bearings are shot, it's highly likey the cones will be too & naturally the inner surface (cups) in the hub shells. If this is the case you'll never get them smooth again, though new cones & balls will make the best of a bad job.
Frequent re-greasing is the way to prolong hubs etc, waiting for 'play' to appear is too late.
 
Cheers chaps, will have a look for some decent ones. Both hubs run pretty well (rear is like butter !!), front has no play but just feels ever so slightly rough (suspect balls are just starting to go off). Bike has been really well looked after.
 
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