bowlofsalad

Off and on I've looked into the subject of things like ABEC and loose ball bearing grades. Looking into this subject is rather frustrating as all I seem to find are an endless fountain of worthless opinion or worse.

I have been hoping to find a series scientific measurements used to do comparisons on some sort of level of effeciency or power consumption in some sort of chart or article.

Do you know of any?

Thanks

dsbrantjr

As an engineer I live on scientific data, and I applaud your efforts to obtain it, but the information you seek will likely be of little use in improving bicycle performance since ball bearings contribute such a vanishingly small amount to the effort required to move a bike along that an order of magnitude improvement will be unnoticeable.

Airburst

+1, given that you don't notice the effect of a slightly over-tightened cup-and-cone hub while riding along, and that that's an order of magnitude more drag than low-grade bearings would cause, I very much doubt there's any difference from using better-grade bearings other than possibly longer bearing life.

Anyway, isn't the ABEC number thing just a measure of how fast the bearing's rated to spin or something? I remember seeing an article ages ago explaining to skateborders why paying ten times as much for ABEC 7 bearings rather than just using cheaper ones was pointless, because even the lowest rating is massive overkill for the wheels on a skateboard.

headloss 

The Truth about ABEC and Skateboard Bearings

Airburst

There it is, looks like I misremembered some of the details, and also what ABEC numbers actually are. I don't think we use them in the UK, as an engineering student I'd like to think I'd remember if I'd been taught them...

I wonder if the cartridge bearings in bike parts are labelled as dodgily as skateboard ones...

headloss 

Timken has a lot of good resources, but the closest thing I can find is looking at comparable fatigue life, not efficiency. I'll keep looking. https://www.timken.com/EN-US/Knowledg...aringLife.aspx

I would certainly assume so. There's a market for perceived gains in any of these hobbies.

In response to the OP, I don't think you will find some chart that is scientifically comparing say a Shimano cup-and-cone vs. a legitimate ABEC rated cartridge bearing except for maybe by Shimano themselves (and there's a good chance that they don't even care).

I imagine that the data on a Shimano, Wheels MFG, (or any brand) cup&cone in regards to tolerances isn't public knowledge. So while we may know the tolerances of the ball itself, that's only 1/3 of the complete picture... and even that is then subject to how they are loaded, adjusted, and lubricated.

I don't think that for industrial applications there is any need to compare, that companies just trust in-house engineers or Timken, SKS, etc. to determine the best style of bearing for a given application. The goal being longevity more than efficiency (assuming that differences in efficiency are either negligible or outweighed by other requirements that necessitate a particular type of bearing and/or lubrication (thrust/radial/axial stresses, electrical current, load, speed, etc.).

nfmisso

As a Mechanical Design Engineer who has spent sometime designing systems with ball bearings and ball bearing cartridges; I am not aware of any publicly available research into this area. Timken, SKF, NSK, NMB, etc do from time to time fund research at universities or do research in house on how bearings work and how to improve a particular aspect of a bearing system. These are almost always proprietary, and intended to support a particular customer opportunity.

Ball and roller bearings are an incredibly mature technology; resulting in a very small (and very expensive) amount of improvement being available. I have not seen bearing power consumption as a function of bearing tolerances or geometry been research during my professional career. The only research projects that I have seen on bearing power consumption or torque where comparing different grease formulations and amount of grease used. On ball bearing assemblies in a very well protected environment; very low grease loadings of very special grease is used. Most of the research has been related to life and durability, not power consumption.

Bicycles are incredibly small part of the market for ball bearings; probably far less than 1%; with the double whammy of low profit margins. The business is not sufficient to attract the attention of bearing manufacturers. To give you an idea of scale, Seagate makes more hard disk drives in one day than all the bicycle manufacturers in the world make in a year.

noglider 

I never believed bearings had much of a bearing (ha!) on bike performance, but what about on durability?

FBinNY 

The effect of the grades on resistance is nearly nil. That's not what it's about.

The balls ride in constrained tracks whereby each is in contact with both races at all times. Therefore the separation needed for the larger balls would reduce or eliminate the contact pressure of smaller neighbors. (if you don't see that conduct an experiment whereby you place a row of similar objects in a row on a table and place a straight edge across them. Odds are, that even if they're very similar, at least one won't be touching the ruler).

So, mismatched balls mean that some don't make contact, or not as much, and greater load is taken by the larger ones. That causes vibration and higher local surface stress, as the larger balls pass by the loaded area. That higher stress increases wear and shortens bearing life.

So the reason for closer matching of balls isn't lower rolling resistance, but improved bearing performance, ie. cooler running, lower vibration etc., and longer bearing life.

HillRider

If that's the case, bicycles have got to be one of the lowest demand applications in the world for bearing balls. The loads are moderate, the temperature demands laughable and the required bearing life a tiny fraction of what industrial users expect. Say you overhaul your hubs every two years and ride 10,000 miles at an average of 15 mph on them between overhauls. The total hours are 666 or about 28 full days. Industrial bearings are expected to last 10,000 to 50,000 hours or 1 to 5 years of continual use.

FBinNY 

True, but on the other hand, the bearings are matched to those conditions. Plus the bearings run under less than ideal conditions. Either way, bearing failure due to wear, isn't all that common, nor uncommon, so the folks who build and spec them seem to have dialed it in pretty decently.

In any case, I consider grade 25 the go to buy. It's serious overkill compared to need but the upcost is tiny making it a very cheap luxury.

HillRider

Agree completely. Grade 25 is the "sweet spot" in availability, cost and quality. Lower quality doesn't save much and higher quality gets expensive fast with no benefit.

dedhed

I would guess the grease viscosity, especially at lower temps, would have much more effect on power consumption than bearing grade.

headloss 

I'm not even sure how much that matters if the grease is the "channeling" type. For non-channeling, viscosity would matter more, I imagine.

davidad

High quality bronze bushings would be adequate for our usage.

rydabent

After working in the computer industry for 47 years all I can say is if possible buy American made ball bearing. Virtually all the bearing failures I have seen in all those years was from Japanese or Chinese made ball bearing.

flatlander_48

Perhaps, but what happens is that as they wear, effectively the tolerance increases. I don't think there is a way to close that up. Also, other than excessive load and corrosion, dirt is a killer. Bronze bushings are used in conjunction with a hardened axle. Any dirt that gets in imbeds itself in the bushing, but over time it can cause wear in the hardened steel. Also, with a hardened axle, you would probably need to anneal it to keep it from being brittle. Probably the money you would save with the bushing you would give back with the axle.

davidad

I realize that durability would be lower than a good ball bearing hub or BB. What I was saying is that there is little gain in friction reduction at the loads and speeds we encounter.

Mark Kelly 

A few years ago when ceramics became fashionable I measured some jockey wheel pulley bearings directly, comparing plain bushings (Campagnolo original) to steel and ceramic ball bearings.

IIRC there was a very small (but measurable) difference between the bushings and the bearings. There was bugger all difference between the two types of bearings.

noglider 

Well? Hmm.

In a headset, no, because friction would hamper steering feel and control.

In hubs, maybe, but when play developed, it would be disconcerting.

In bottom brackets, absolutely not. There's a lot of force going through there. The bushings would wear out fast.

Pedals? Yeah, maybe.

Freehubs? Yeah, maybe.

Airburst

Emptying out the collection of mostly-useless bike trivia in my head comes up with a few things.

Point 1: Raleigh Twentys (at least some of them) had bushings for the top headset race. I've never ridden one, but according to Sheldon Brown, the additional stiffness didn't compromise control during normal riding, although it did make riding no-handed hard. Not sure how that would translate with different frame and fork geometry though.

Point 2: I'm fairly sure I've seen hubs advertised for DH bikes that have PTFE bushings in them rather than bearings.

Point 3: There definitely were some horrible cheap pedals made at some point that didn't have ball bearings in them.

noglider 

I have one of those Raleigh Twentys with the bushing for the top headset bearing. It is very disruptive to me. I am in the process of replacing it.

What are DH bikes?

What did you think of those horrible cheap pedals (well, I know you think they were horrible) and how did you think the choice of bushings bore into their horribility, to coin a word?

Retro Grouch 

BUT, anything you can measure and rank, has to have a high and a low score. Whether the range between the two is significant is another matter.

Airburst

DH stands for Downhill, as in the ridiculous mountain bikes with about a foot of suspension travel at both ends. Sorry if that was confusing. I think the logic behind bushings was that the bikes don't really do a lot of miles, but the impacts they subject parts to are massive, and maybe the designer thought bushings would survive better than ball bearings.

I can imagine a bushing headset being annoying, I'd imagine it would feel like the headset was horribly overtightened, and even if it's perfectly rideable I'd imagine it ruins the zen feeling (or whatever you like to cal it) of riding a properly adjusted bike. What're you doing, just putting the top half of a 1" threadless headset in there and pushing it down somehow to set the preload, or threading the fork or something?

The only time I've seen bushing pedals, the bushings were already severely worn, but the rubber pedal bodies had perished and were all cracked, so I think they were fairly old. It was a co-op donor bike, so the pedals just got thrown away. I can imagine bushings working on those throwaway plastic pedals, as the ball bearings in those are usually still absolutely fine when the pedal body's falling apart (usually after about six months), but I'd be concerned about their longevity on a pedal that's designed to last a bit longer.

HillRider

Down Hill.