How many balls to put in a bearing? I'm cleaning out most of the bearings on my new (second hand) bike.

I'm replacing the grease inside the pedal bearings and I was wondering.

How many ball bearings should be inside? I thought there had to be just enough to fill the full circle, but a friend of mine told me I should fill the circle to its fullest and then remove one ball.

The reason, he said, is that else there is to much pressure on the bearings.

Is this true? And is it true for all the bearings (say, the ones in my hubs)?

And also, I'm putting vaseline (the yellow heavy-duty variant) inside the bearings&nbsp;&ndash; is that a good idea?
The reason behind the "full less one" is that you need at least half the race full (rounded up) for it to work and performance improves with more balls past that point, but if it's too full you get a dramatic loss in performance. So "full less one" is an easy guide.

In practice most bearings spread a little as you tighten the cones so "full" when you're adding balls is not actually full in use. You can usually see this - when you're adding balls they generally sit in against the axle, then when you add the cone it spreads the bearings slightly. So filling the race is almost always fine.

Don't be tempted to add one more to fill in the extra space created when you tighten it up, this is exactly the situation the "full less one" guide is trying to avoid. That "full plus one" means all the load is on one bearing (and one section of the cone), plus the bearings are really grnding against each other as the wheel rotates. If you're lucky the wheel won't rotate in this situation, but if you're unlucky you're wreck the cups and have to replace the cups (or hub, if the cups are not replaceable).