koger

Hi

Doing a bit of service on my Shimano WH-R501 hub for the first time. After carefull disassembling the front hub I have 20 bearing balls. According to the manual there should be 22 balls. I could have dropped 1 ball, but I don't think I have dropped 2. I havn't serviced a hub before, but it seems that 11 balls looks more correct than 10 to me, with 10 balls, there seems to be one missing.

Should I just use the 20 ball I have or buy two more?

FBinNY 

Some will argue otherwise, but it's never good practice to add a ball or mix balls in a set. High quality balls are made to an order of tolerance closer within a production lot, than the general tolerance. So mixing balls is like going back to buy paint for a small touch up two years later --- close but not perfect.

As for whether you "should" have 10 or 11, I tend to defer to the maker, and one hint is whether you bought the hub new, or someone else might have serviced it before you. Or you can test by assembling a cone into a cup dry while in the palm of your hand. (better yet if you can see it). Add the 11th ball, and test by spinning the cone. The balls should not touch each other at all, except for incidental contact of some now and then. Unless there's a gap you can move around with a spoke you have too many balls. If you can push all the balls together and end up with a gap larger than a ball, you have too few.

Either way, while you have things apart, you can treat your hub to balls better than it really needs at little added cost by buying grade 25 balls (within 25/1,000,000" in the same lot).

I keep small packets of spare balls in the core sizes, so I always have spares when servicing hubs or other bearings. That frees me from worry about dropping, mixing or losing any. It's about the cheapest indulgence there is.

fietsbob

I buy them in bags of 1000.

hueyhoolihan

if i had a hub and had doubts about the number of loose ball bearings that it was designed for, i would put as many in as possible, and if there was less than 1/4 balls width left over, i might remove one.

assuming i didn't have another hub to use as an example or possibly a manual around. or a know-it-all that insisted that a particular number of ball bearings was correct and would be offended if i didn't take his word for it. or any number of other reasons really.

CliffordK

You have 20 balls.
You can take 11 of them and put them in one side, and see how it looks.

Then decide if you're going to buy 22 more.

I find the new hubs tend to trap loose bearings behind the bearing race. Carefully probe behind the race with a screwdriver or something. It never happened with the old skinny tube hubs.

cyccommute 

The bearings in a hub should look like you can fit one more in but it really won't fit. In other words, there should be a gap that is just slightly smaller than a single ball bearing.

Andrew R Stewart 

The location within the cup that you place the balls (assuming you reassemble the "common" way) isn't always where they will roll when a cone is installed and spun. So looking for that extra ball's space isn't as straight forward as some might think. If you over load the complement with one ball too many the cone will ride up and off to one side by a bit. This will cause the rim to look like it's out of true. But the "wobble" rotates about at half the wheel's RPM as the bearing is running at half the wheel speed and the out of place ball shifts it's point about the hub's axis. Andy.