Originally Posted by Rogerogeroge

What I'm saying is if you have to replace 18 bearings in your rear hub, and you have a year old bag with five bearings left, don't combine them with a bag you just bought. The old bearings might be 0.12504 inch plus or minus .00001 inch, and the new batch is 0.12506 inch but still plus or minus .00001 inch. So you could end up matching a 0.12503 ball from the old batch with a 0.12507 bearings from the new batch, which could be a significant variation. I'm pulling numbers out of my head trying to illustrate the point, but I've read something to this effect.