Shimano cup and cone front hubs, how many balls?

[Gattopardo]

Ok now this is a stupid question but think something is wrong with a front hub.  Search shows that there should be 10 3/16 balls in the front, yet there seems to be space enough in the hub for 11 balls even when greased.  Seems odd as other front hubs I have cleaned and regreased don't have the space for an extra ball.

The balls seem to be the same size as other front hubs, didn't check or measure but feel the same.

Any ideas, as I'm ordering some ball bearings so was thinking of just replacing all the balls.

[Hot Flatus]

Its 10 iirc. 

12 years ago an LBS trashed my hub by putting in one ball too many.

[Jakob W]

Isn't the general rule for uncaged balls "(As many balls as will fit) - 1"?

[Tim Hall]

Isn't the general rule for uncaged balls "(As many balls as will fit) - 1"?

This.

[Brucey]

with shimano hubs the number of balls is indicated on the SI techdoc for that particular hub, so just go with that.

If in any doubt, add the balls as you see fit and firmly finger tighten the cones. If there are too many balls then the bearing will start to bind. Compare this condition with one ball less and you will soon feel the difference.

If there is meant to be 10x 3/16" balls (for many years the most common arrangement in a front hub) then putting in 9 balls is pretty bad too. Likewise if you have 8 balls in a rear hub when there is meant to be 9.

FWIW many  shimano front hubs are easily ruined by the balls not all  being in the cup before the cone is screwed in; often one ball manages to escape and can sit on the corner of the bearing cup still behind the dust shield. If you ride the hub like this the bearing can start to break up within one mile;  I found this out the hard way when I was a spotty teenager, and I have seen several hubs that have suffered a similar fate since.

cheers

[Adam]

Its 10 iirc. 

I've found a hub which had 9 one side and 10 the other, and I'd never opened it up previously.

[Gattopardo]

with shimano hubs the number of balls is indicated on the SI techdoc for that particular hub, so just go with that.

If in any doubt, add the balls as you see fit and firmly finger tighten the cones. If there are too many balls then the bearing will start to bind. Compare this condition with one ball less and you will soon feel the difference.

If there is meant to be 10x 3/16" balls (for many years the most common arrangement in a front hub) then putting in 9 balls is pretty bad too. Likewise if you have 8 balls in a rear hub when there is meant to be 9.

FWIW many  shimano front hubs are easily ruined by the balls not all  being in the cup before the cone is screwed in; often one ball manages to escape and can sit on the corner of the bearing cup still behind the dust shield. If you ride the hub like this the bearing can start to break up within one mile;  I found this out the hard way when I was a spotty teenager, and I have seen several hubs that have suffered a similar fate since.

cheers

How to identify a hub?  The press on caps say shimano, hence knowing it being shimano.  But there are no other visible identifiers and the hub is of an unknown age with a wolber rim.  The bike is a 531 fw evans bike, so no dea how old the parts are.

[Brucey]

a photo would help; someone will recognise it for sure.  'Wolber' branded HP rim suggests very strongly it is a 1980s wheel; prior to a certain date the same rims were known as 'Super Champion' rather than Wolber.   If it is a 1980s shimano road hub it is almost certain to be 10 x 3/16" balls; I don't remember them making anything else.

cheers

[Gattopardo]

Here are the photos for IDing the hubs:

[Brucey]

that looks a lot like a HB-RM50 to me (originally it would have had a sticker on it saying so, but that will have fallen off)



https://si.shimano.com/pdfs/ev/EV-HB-RM50-0981B.pdf

10 x 3/16" balls each side

cheers

[Gattopardo]

Thank you