kleng

Hi

I was wondering which setup is more efficient and smoother running in a Dura-ace WH-7801 front hub.
The shimano spec is to use the retainers but for some strange reason my hub came with loose bearings and 2 extra bearings (to make up for the missing retainers) on each side.

14 x 5/32 bearings in a retainer or

16 x 5/32 bearings loose

Thanks

DMF 

How tight are they packed in the bearing? 16 may be too many. Are the wheels new from the factory?

A bearing retainer keeps the balls separated and prevents them from rubbing against each other. It also increases the load on each ball since there are fewer of them. But it keeps them evenly spaced so the hub is more likely to run smoother, depending on the condition of the balls.

I prefer to use retainers where they're originally fitted. But I don't see a compelling reason to prefer one over the other in every situation.

kleng

The wheelset was new from the factory, but I've ridden 6,500 kms on them, and this is the first time I have looked at the hubs. The 16 is n-1, there is room of another bearing in the races. Everything is in good condition except that without the retainers it isn't up the to Shimano design spec, just to be safe I'll put in some retainers which I'll need to order from Shimano. Thks

HillRider

I just looked at the Shimano web site and, sure enough, they spec retainers in the WH-7800 hub. That's a first for me since I've never seen Shimano hubs of any model with retainers. If they were mine, I'd continue to forgo the retainers and just use loose balls the way your wheels were actually assembled.

TallRider

Very interesting - I've only seen bearing retainers in cheap-*** hubs on cheap-*** bikes.
I'm with HillRider here - your hubs should be fine as-is with loose bearings. Nearly every other top hub (including Shimano) that doesn't use cartridge bearings has loose bearings, not in a retainer. So perhaps it doesn't matter much, as DMF says.

Bob Dopolina 

Campagnolo uses resign retainers for all hubs and wheelsets.

kleng

I spoke to Shimano tech about my strange hub, and they said that there have not been any complete wheelsets in the Dura-ace range since 2005 that used or uses loose bearings. They said that factory quality control would prevent the wheelset leaving the factory without bearing retainers, so they think Giant in Australia or the LBS might have modified them.

operator

There's actually another level of cheapness that is lower than what you mentioned. None of the bikes I work on even have retainers in the hubs. It's all loose in there. New bikes mind you.

TallRider

Only Campy wheelset I've worked on is 2000 Mirage that has loose balls in front hub and cartridge bearings in rear. When did Campy start doing this, and how quickly did they phase it throughout their line?

Bob Dopolina 

Can't remember the exact model year off the top of my head. Take a look at their parts schematics.

Interestingly the part number for all Campagnolo bearings is the same: HB-RE023 (except for the ceramic options or the cartridge bearings) which means the bearings in your Chorus hub are the same ones that are in your Record hub or your Eurus, Shamal, Hyperon, Zonda, Neutron, Proton or Bora wheelset.

Had some in my hands, today in fact.

tellyho

I thought the general consensus was that loose balls was better: more weight-bearing surface, less friction. I'm in the habit of ditching any retainers I find when I overhaul.

well biked

I'd be very interested in knowing why Shimano uses a retainer only on Dura Ace hubs......or are they currently using retainers in other hubs as well?

jjciiijs

Pulling the cages is an old practice to improve smooth running. Lets the bearing revolve without resistance.

well biked

My experience as well, and in addition I believe loose balls make bearings last longer. But again, why is Shimano using retainers in their highest end hubs, when they use loose balls in their other hubs (at least the ones I've seen)? It's also pretty well accepted that retainers make assembly easier, a major concern for manufacturers, I would think. So if Shimano is going to use retainers in their Dura Ace hubs, why not use them in ALL their hubs?

jjciiijs

Your answer is there, 'easability' ( is that a word) plus, the amount of resistance we are talking about is and or could be, just going overboard.

well biked

Right, I believe the main, maybe the only, benefit of caged bearings on a bicycle is ease of assembly. But still, this doesn't answer the question: why only Dura Ace, of all groups? Or has Shimano begun using cages in all their hubs?

Metaluna

This came up in another thread so I looked through some of the spare parts manuals on the Campy website. It looks like they started introducing the bearing retainers around 98-99 or so with the last major redesign of the Record hubs, and eventually migrated the design to Chorus and Centaur. Veloce, Mirage, and Record Pista appear to use various other designs with either loose balls or cartridges. Now with the '07 stuff they appear to have gone to cartridge bearings on everything below Record. Record is more or less still using the classic design with the retained ball bearings and adjustable cones.

DMF 

When loaded balls contact each other, there is much more friction than ball to (unloaded) carrier contact. a) the loaded balls can't easily move apart, b) the contact velocity is double that of ball to carrier.

If there is a slight size difference in the balls, they will tend to bunch behind the smaller ball and eat energy.

DMF 

They often introduce new things in DA then move them down the groups. We'll have to wait and see.

operator

Which is the exact reason why you don't mix and match and use all bearings from teh same batch

Bob Dopolina 

Actually Chorus is still a bearing with retainer as well. Plus, if you look at their wheelsets, as I mentioned, most of them use the same bearing with resign retainer. The lower end wheelsets (Khamsin, Vento and Scirocco) use cartridge bearings.

This point of loose vs caged came up in anther thread recently but no-one ran with it. I mentioned there that I used to use loose bearings exclusively but now am not so sure. My reasons for this are twofold. First, I find when I am adjusting a loose bearing hub, I can get it to run very well but I can also find a spot (briefly) where there is play. This is pretty conclusive evidence (of the obvious assumption) that they are moving around in there.

This brings me to the second consideration. If they are moving around so much, they must be rubbing against one and other. This would increase friction in the system. It is much like rubbing tires when you are riding with someone; Even though you are traveling in the same direction the back of the rear wheel is going up and the front of the front wheel is going down. Bring these two together and you have friction. So if you reduce friction by adding more bearings (as loose bearings) are the gains made here offset by the increased friction of the balls rubbing against each other?

Throw in a retainer. How much friction is there between the retainer and the bearing? If you use a resign one, like Campagnolo does, I'm sure this is reduced (as well as the potential wear or damage caused by the retainer itself) but again, by how much?

Considering that both Shimano and Campagnolo use retainers in their top o' the line products may be a clue. This could also relate to production where a retainer is much faster to use during assembly (but if you've every seem women on an assembly line lace a wheel you could certainly overcome this if it was worth it).

As both companies spend considerable time and money on R&D, it is unlikely they will be forthcoming with any hard numbers. Has anyone else out there got any real data on this issue. Anecdotal evidence like' "I been running such and such in my such and such for years and it works fine." doesn't really cut it.

Any rocket surgeons out there who can help?

HillRider

To my surprise, I checked the owner's manuals for my '06 Chorus hubs and both the front and rear hub illustrations show the bearings in retainers. I haven't had these hubs apart yet but that's the way the book shows them. The books cover Record, Chorus and "Daytona" and were copywrited in 1999 so the name change to Centaur apparently hadn't occured yet.

So, it seems the change occured by the end of the '90's, at least for the upper line hubs.

JanMM

I doubt if any significant data exits that shows a real world difference in performance or durability between caged and loose balls. Follow your heart.

Bob Dopolina 

That's my suspicion,too but you never know. There are a lot of guys out there with time on their hands...

well biked

I'm wondering if it doesn't have a lot to do with the design of the specific retainer. Scientific or not, there's an awful lot of anecdotal evidence that tossing the retainer on the average old headset or cup and cone bottom bracket and repacking with loose balls is an improvement in most every way (except ease of assembly). Heck, if I can see, feel and even hear the difference just by spinning the part, that's pretty strong evidence as far as I'm concerned.

But, for instance, Bob, what the heck is a "resign" retainer, like you mention with the Campy hubs? See, I think when we're talking about these Dura Ace and Campy hubs with retainers, we may be talking about a whole 'nuther animal than the average old headset or bottom bracket as far as the actual retainers. I know that in industrial applications, too, there are specially engineered retainers that are there to increase performance and service life of the bearing assembly, and I'm wondering if the retainers on these quality hubs aren't more like that than the old retainers most of us think of when we're talking about retainers on bicycles.

This is just a thought, though, because I've never even knowingly seen a bicycle hub with bearing retainers in it, so maybe the retainers in these hubs aren't all that different than the retainers in a $15 headset. So what are the retainers like in these quality hubs?