TallRider

I'm just overhauling the hubs of the late-80's Centurion road bike that I bought on eBay. 105 hubs, good design. But to my susprise, the front hub was one bearing short on both sides of the hub. (That is, you could fit one more bearing in there, to fill the hub - it was an obvious gap; I've overhualed a lot of hubs in my day and know how bearings are supposed to fit.) The rear hub was one bearing short on the non-drive side, but had a full complement of bearings on the drive side.

Now, is there any reason that this would be done? Or does it just indicate stupidity and carelessness on the part of the last person to overhaul the hub? (Or spite on the part of the eBayer?)

Thinking about it, I doubt this would do too much harm. Bearings that use retainers never have 'the full complement' (but of course, they're not used in hubs, either). But the "gap" from the missing bearing rotates around the hub's races and the cone, and results in slightly unequally distributed forces, but at least the point at which the forces are unequal doesn't stay in the same place on either the hub's races or the cone.

Still, I can't think of any reason to do this.

jemoryl

Components often come with ball bearings in a retainer. When rebuilding, loose balls will often be used to replace the originals. To determine the correct number of balls to use, the rule of thumb is to fill the cup completely with balls and then remove one. I suspect that is what you are seeing with these hubs.

TallRider

I've never seen hubs that came with bearing retainers. Have you?

When I repacked my more recent 105 hubs (from 1995) this past summer, they had the full complement of ball bearings.

What is the reasoning for leaving out one ball? I've never heard of this "rule of thumb" though I'm certainly open to it.

ofofhy

I have heard this "guideline" before, but I have always used the full complement of bearing balls in hubs, BBs, and headsets.

San Rensho 

If you have too many balls in the cup, the cup and race won't mate with the bearings. I made the mistake of filling a headset race with bearings and failing to remove one. The headset had lots of play and I could barely turn the bars until I took it apart and took one out.

Try it both ways, if the bearings adjust, then no problem.
Same components might have enough space, but when in doubt, take one out.

powers2b

The 'Missing' ball allows the bearings to turn without grinding against eachother.
I guarantee if you look closely in all bearing cups there is a space that is 1 to 1/2 the diameter of the bearing.

Enjoy

spunkyruss

I have seen hubs containing balls in retainers. They were on my low-end Specialized Hardrock from the mid-90s. I've repalced them with loose balls.

I can't recall the source of my information (or misinformation as the case may be), but I am under the impression that a race that is packed full of balls will generate more friction than a race that contains one less ball.

The exlplaination was that friction is generated between adjacent balls if they are all touching. As the bearing spins, one side of each ball is rotating towards the upper race and the opposite side of the same ball is rotating towards the lower race. If all of the balls are touching, then then the upward-rotating side of every ball is generating friction against the downward-rotating side of the adjacent ball.

If the bearing doesn't contain enough balls to place adjacent balls in contact with one another then the friction will be reduced.

I could be wrong about all of the whole ball-on-ball friction thing.

TallRider

This sounds like having +1 ball, not -1 as in the hubs that I opened up.
-
This totally makes sense. It seems, though, that hubs should be designed for this - there's room for 1/2 extra ball, not a whole one. Given that hubs aren't designed this way, it seems that they're not designed with having the -1 in mind...

jemoryl

Yeah, some cheap hubs use retainers, but I suspect not those at the 105 level. But the principle should be the same - you don't want the balls interfering with their neighbors. I have felt some components where the cups were over-packed with balls and they did not turn as smoothly as when a ball was removed.

Al1943

Typically you can squeeze in one too many balls. Take one out.

Al

cascade168

I posted this in another thread, but I think it's of use here, also. Please forgive me for the multiple
posting ---


BikeToolsEtc has a nice little reference cheat sheet in their catalog for replacing caged balls with loose. I will paste it up here:

" Component Loose Bearing Sizes (Exceptions Exist)
Components..................Size..........................Bearing Count
Bottom brackets.............1/4".........................11 each side
1" headset.....................5/32".......................25 per cup
1 1/8" headset................5/32 or 3/16"............20-28 per cup
1 1/4" headset................5/32 or 3/16"............26-31 per cup
front hub........................3/16"......................10 per side
rear hub.........................1/4"........................9 per side
pedals............................5/32 or 1/8".............10-15 per side
SPD pedals.....................3/32".......................lots
If in doubt, fill space with bearings and remove one.
It is possible to replace the balls in a bearing retainer that's in
good shape. Just pop 'em out and pop in new ones of the same
size. "


As they say, "exceptions exist", but I have yet to find one myself.
It's a pretty good list.

Avalanche325

To be like Lance????

Man, was that in poor taste, or what???

Al1943

Good explanation, I think you are exactly correct.

Al

Rev.Chuck

SPunkyruss has an explanation,about friction between the balls and that is true. Another reason is that you cannot tell exactly how the balls will sit when the unit is assembled and the fill it up remove one method ensures that they will not bind on one another.
This was a rule I heard of twenty years ago when rebuilding loose roller bearing transmissions.

DieselDan

EVERY Shimano E-110 coaster brake hub has retainer bearings.

HillRider

Every Shimano front hub I've ever worked on has 10 3/16" balls per side with the exception of newer Dura Ace which has 11 per side. ALL Shimano rear hubs have 9 1/4" balls per side.

DieselDan

Watch out using words like ALL. Again, the E-110 is an exception with 8 in a retainer.

HillRider

OK, let me qualify that. All REGULAR Shimano road and MTB hubs have 9 x1/4" balls per side. I really didn't expect coaster brake hubs to be part of this discussion. And, without the retainer, I expect 9 loose balls would fit in the E-110.

DieselDan

Shimano makes more E-110 coaster brake hubs then all other rear hubs combined. Loose bearings tend to jam the driver, causing it to lock up.

HillRider

I know why they make so many of them. The largest catagory of bike sold are childrens. I repeat, we weren't discussing coaster brake hubs here.

Bikebros

This last summer, I added one bearing to most of the Shimano Deore front disc hubs on complete bikes (I open up all the bearings during assembly to check for such things as #of bearings and to put quality grease in). There was easily room for the additional bearing, and i don't recall ever noticing a hub with such an obvious gap to add another bearing.
By the "rule of thumb" mentioned earlier, I shouldn't have added a bearing, because there wasn't room for an additional one after the one I added. By the way - I have never heard of the remove on bearing rule of thumb.

I don't relate to any of this - I don't think I have ever jammed too many bearings into a hub - it has always seemed pretty obvious how many the right amount was (as long as the bearing size was right).

My point.... I don't know. I guess I'll try to rationalize some of the theories mentioned.

If there truly are too many bearings, one bearing ends up partially displaced by the pressure from the other bearings and it becomes obvious quite quickly that there are too many.
The "two bearings rubbing in opposite directions unless one bearing is removed" theory is flawed. Bearings tend to group together - they never appear is if there were an invisible retainer holding them apart to stop rubbing. By removing a bearing, you end up with a group of bearings all touching, then one spot where there is a gap. This gap migrates to the loaded side of the hub (the bottom), forcing the remaining bearings to come into loaded contact with adjascent bearings - so there is still contact. If anything, by having one less bearing, the loads placed on the bearings are shared by one fewer bearing resulting in an extra load being carried by the remaining bearings - causing premature bearing/cup/cone wear.

peripatetic

Hmmm. This is interesting, though. I'm no expert, but I'm going to take a slightly different view of your scenario.

If the gap is bigger, as you say, and on the load side (the bottom), then doesn't that mean that the load will actually be distributed to the balls on the sides more? i.e. By your reason, if we filled the gap with another bearing, then wouldn't that bearing (the bottom, gap-filler) be getting most of the load now? On the other hand, with the gap there, then the load will be distributed to the bearings on either side of the gap more evenly, rather than one bearing at a time getting the majority of the load (and therefore creating more friction.)

I'm totally unversed in this stuff, just putting forward an alternate visualization. I like yours, BTW, it's easy to see in the mind's eye.

Interesting discussion here, all.

genec

Opps, lost two bearings on one side... take one out of the other and balance the loss. Not a great reason, but if the shop is closed and two bearings just slipped down the drain, sure beats not riding the next day.

As you point out missing one bearing will not kill the races.

powers2b

And to think Schamano hired all those silly engineers and QC managers.......

Enjoy

meb

The bearing retainers reduce assembly labor time so they are done on low end bikes as a cost saving measure. They add friction, so you are only going to see hubs with bearing retainers on low end bikes wherein performance sacrificing is done in the name of cost saving.