sweeks

Yet this sort of damage seems not to occur in bicycle bearings. I think it is because when the balls contact each other it is not with great pressure. Sliding friction is proportional to the "normal" force, which in a bearing is the pressure of a ball against another at its point of contact. If this pressure is low, so is the friction. Also, these are surfaces lubricated with grease that typically has pretty good film strength.
Steve

Lakerat

I'll surmise that bearing cost vs retainer cost isn't much of a factor. Both are cheap on an industrial manufacturing scale. I doubt a retainer saves money compared to adding a ball or two.

I also doubt that factory assembly convenience is much of a factor either. I assume automated systems for assembling with or without retainers is easily doable. Retainers are certainly convenient for repair during use, and may have some perception of value or preference to most users. Freewheels never seem to have retainers and apparently efficient methods of manufacturing have been utilized.

When retainers are employed by manufacturers such as low end vs high end hubs, does little to explain the benefits of either system. Weight could be a bigger factor than friction. The diameter of the bearing track seems to be more of a determinant of whether retainers are used than anything. Larger diameter tracks having retainers, and smaller ones without, excepting freewheels.

The OS system used by Campagnolo and Fulcrum, replaced common loose ball cup and cone hub designs used by Campagnolo for about 70 years. If you put any validity to the: "low end = retainers, high end without" theory, Campagnolo's redesign doesn't support it. This redesign increased the bearing track diameter and added plastic retainers.

Plastic retainers add another factor in that they may have different friction characteristics than metal retainers. They may also be more consistent in contact points with the bearing ball.

It's also possible that bearing contact without retainers is more of a problem with less precise cones and races. I can imagine balls bouncing off each other happily in a Dura Ace hub.

dedhed

Looks like a lot of hand assembly here.

SquidPuppet

Mounted rim tape, tube, tire, inflated, done................ 27 seconds.

WizardOfBoz

SKF, no slouches when it comes to bearings, has a page on bearing retainers and talks about the bearing minimizing axial runout:

Enables several benefits

By significantly reducing any axial clearance between the bearing and gearbox housing, the bearing retainer helps optimize overall gearbox efficiency and NVH (noise, vibration and harshness). Full benefits include:

Optimal stiffness in the bearing arrangement
Enables gearbox length reductions
Reduced system costs
Improved operating efficiency
Reduced noise and vibration
More compact, lightweight designs
Optimized designs before prototyping
Reduced development time
Simplified assembly

SMB had comments on retainers

Retainers keep the balls evenly spaced around the raceway preventing ball to ball contact and allowing higher speeds. They also help to retain grease around the balls and raceways.

Full Complement (F/B)

A full complement (or full ball) bearing contains extra balls and has no retainer. It is used for its greater radial load capacity although axial load capacity is very small due to the risk of the balls fouling the filling slot during rotation. These bearings can only be used at low speeds and bearing torque is increased due to ball to ball friction. An exception is a hybrid full complement bearing (ceramic balls) which can be used for higher speeds due to the lower friction coefficient of the ball material. Improved steel and hardening techniques have increased the load capacities of bearings with cages and the full complement bearing is much less common now.

• Higher radial load capacity
• Low speed only (except with ceramic balls)
• Low axial load
• Increased bearing torque

A pretty thorough article about cage friction shows that a full ball with cage has more friction than half the number of balls with a cage. That is, more balls = more friction. But the article states that the retainer adds friction as well. Would have been cool to see the data for no retainer.

Anyway, it seems to me that a retainer does more than make assembly easier and reduce costs. It ensure centration, facilitates lubrication, and reduces one source (ball-to-ball) of friction while adding others (ball-to-retainer, guide-to-retainer). And more balls do increase load bearing, but (unless you have ceramic balls) increases friction.

Lakerat

I missed hub bearing assembly, is it on there?

spedrunr

Wow, I'd have to say that this is the most scientific (sounding?) forum to date. And the sentence structure/grammar is to be commended.

I still don't think we've come to a final conclusion(?)

I'm in the middle of rebuilding my bike and would rather not have to tear it down and put loose bearings if the benefit hugely outweighs the caged bearings.

I'm anxious to ride it so I guess I'll keep the cages and go back to loose bearings if the data shows that there is a significant benefit.

Thanks to all of you and your comprehensive research.

Metaluna

I'd say when in doubt, leave it the way it came from the manufacturer. Some of them do actually know what they're doing, and it's not like there's carnage all over the roads from peoples' retained-bearing headsets and wheels exploding. The difference, if any, will be small, especially if you keep up with maintenance.

spedrunr

Not to mention the extra time spent on acquiring the extra bearings, taking out the old ones, the extra time it takes to load up the grease making sure that the bearings don't fall all over the floor when you install the spindle etc.

Again the question to be answered, to what benefit (reduction in the friction coefficient?). I laugh because we try and reduce friction and weight at the cost of making our work out easier. I could see if I were trying to break a world record or win race. Most of my riding is for the benefit of health or picking up small items from the store.

AnkleWork

Another video shows loose bearing hub assembly. They actually pour the balls into place; takes about one second. Bearing cages can't speed that up no matter how many deified sources say so.

Also note in the above video from 2:50 the mounting of a skinny tire takes less than ten seconds.

Further evidence that most of the hand-wringing here is just silly emotion.

spedrunr

15 second chain installation. Hire these people for TDF wrenchers

79pmooney

A couple of thoughts. Headsets - the only issue that matters is axial loading. More balls rule. Hubs - funny how that one of the world's leaders in components, including very high end components used to professional athletes uses loose balls for their best hubs. Are they stupid? Locked in a tradition that just won't die? Or maybe they have access to testing and knowledge we don't.

Ben

rydabent

Both the headset and the BB put high loads on the bearings and races. So the best thing to do is to use a heavy bearing grease. The heavy grease lets you stick the loose balls on the race for easy assy. And yes with the loose ball allow for a little extra space, but more balls will spread the load better.

dedhed

I find the most time is spent going to the fridge for another beer.

Bill in VA

Unfortunately in industry today, it is not the engineers who make the final decisions. The engineer may have a certain design, but bean-counters and marketing tell them to 'control' costs.

spedrunr

frogbiscuit

I will throw my $.02 in. As one who worked in manufacturing (steel, aluminum, plastics, composites) for 35 years, in the grand scheme of things, bicycle bearings move very slowly. The argument for or against retainers is moot in a bearing moving that slow, that why you can get away with greasing it every few years or so. Most high speed bearings used have the inner and outer races attached, so the bearing is thrown in as a unit.
If you drilled a hole in the frame and installed a grease fitting, you would never have to replace the bearing, but that brings up other issues.

And....as an industrial engineer, the difference between taking a few minutes to install the balls and a few seconds dropping in the retainer are huge. That kind of lost time will kill an assembly line.

Mad Honk 

Wiz,
My experience with the ceramic bearings is that no lubrication is necessary for bicycle applications, as well as in outer space. I know a few folks who have replaced pedal bearings with free range ceramic bearings and are quite happy with the no lube part of the equation. I am tempted to try a full bike with free range ceramics but am bewildered by the almost $600 cost of the bearings. Help a stoopid brother out here... Smiles, MH