Mr. Fly

You've failed to consider the whole picture. This demonstration can elucidate differences between bearings but that difference may be entirely insignificant when used in a system, such as a bicycle that's actually carrying a load and being pedaled. As I stated, do we use bicycles with their wheels spinning in air or do we actually put the rubber side down?

HillRider

No, I certainly see the "whole picture" and maintain that if ordinary steel bearings can show such low drag, then ceramic bearing can't make and significant or useful improvement.

Doug5150

If you wanted extra bling you could take the ceramic balls out of some full-ceramic bearings and replace them with some sapphire or ruby balls.
https://www.edmundoptics.com/optics/o...ll-lenses/2050

Ray Evans

Yes hands up I do sell bearings on ebay but forget the engineering and lets drop all these angree bitter remarks :-

The truth, a polished surface is more slippery then a dull one.

A harder surface will stay polished longer then a less hard or tough one like stainless regardless of how polished the steel starts off. its like comparing brass to a diamond.

Ceramics do not expand like steel and are not attracted to any steel casing. This reduces ware.

A good quality nickel grade 5 ceramic ball is NOT very expensive. I should Know I sell them.

And everyone is forgetting the pleasure you get from replacing , maintaining and upgrading your own bicycle.Especially the wheels.

I know this not becuase I worked on the concorde but becuase I sell what I use myself. After all I am like you a cyclist.

HillRider

All of what you say is more or less true but of no consequence except monitarily. Plain steel ball bearing hubs are so long lived and have so little drag that any "improvement" from substituting ceramic balls or even complete bearings is insignificant and of theoretical value only.

cny-bikeman

[QUOTE=Ray Evans;14793292
And everyone is forgetting the pleasure you get from replacing , maintaining and upgrading your own bicycle. Especially the wheels.
[/QUOTE]

I don't think anyone is forgetting that, but last time I looked any true cyclist gets more pleasure from riding than from maintenance. I get pleasure from doing a true upgrade that will increase utility, efficiency or reliability. Ceramic bearings do none of that to a degree equal to, let alone in excess of the time/money cost.

rydabent

There is an old saying "a fool and his money are soon parted". I think that applies to ceramic bearings.

Ray Evans

You got me guys what can I tell you. Lets turn back the clock. We all know there were advantages to for example hubs with little oil wells that you topped up regularly and little wicks that drip fed your bearings.
But go ask your mother to throw away that nano ceramic iron she uses and buy a heavy old cast iron one. Or leave half your egg on the steel frying pan (not the new ceramic one) and spend twenty minutes washing it off.
Or tell every 10 year old skate boarder he should swap out his (bones)bearings for steel ones.

The difference might be small scientifically when we throw in all the obstacles but when I am riding home 20klms after a hard day at work and its raining. I approach the beginning of the last upward push over a crest bridge.
The advantage is enormous.
I love ceramics they work. they are so light it is like riding little beads of air, and if your grease feels like it has too much drag just change it for a lighter one without worrying.

cny-bikeman

If having ceramic bearings helps you that much then great - but it's the same advantage as having a snazzy jersey - if it makes you feel better you will go faster.

DArthurBrown

+1

Not going to second guess the guy that makes a living studying this stuff.

HillRider

Wow, are you the master of the misleading analogy!

Fixed it for you.

Lets see, I just weighed 18 1/4" steel ball bearings, the number typically used in a rear hub, and they weighed 18 grams total. If your ceramic bearings save 50% of that you will have saved 9 grams. Whoopie!

Shimagnolo

Uh. oh! Wait til the fixie crowd learns about this!

Ray Evans

Woke up this morning and thought wait a minute if all else is equal which it is not. And if we all use ceramic the price will go down becuase the supply will increase.

What about enviromental issues?

I grew up in a steel town watching those smoking stacks poluting the adjacent mountain.
Not even a tree survived. I am not an expert but surly ceramic is better than steel for the enviroment.

Ray Evans

It is a big whoopie over 20 years of your life or and when all else is equal in a race, every little counts right weight weenies. There is a Japanese car designer taking one thread of each bolt. And a famous world champion cross country skier in Sweden took 2 inches off his pole length.
why dont you add 18 grams (two wheels) to your rain jacket next time your out for a ride.
Or a jockey on a horse can be disqualified if he is 18 grams lighter after a weigh in.
Plus you can go the next step ceramic, jockey wheels and bottom bracket . It all adds up.
Oh by the way its 60% not 50% lighter.

wroomwroomoops

Extraction and refining of zirconium and yttrium consume vastly more energy and are HUGELY polluting - the very reason rare earth metals aren't being mined in the US at the moment (or at least, much less than in the past) is because it's an immensely polluting process, so we let it do by the Chinese. I'd say that producing the same amount of ceramic ball-bearing material as steel, releases three or four orders of magnitude more pollutants into the environment.

In the case of silicon nitride, the problem lies in the amount of energy used to refine silicon, and then to sinter silicon nitride into the desired shape. Again, we're talking two to three orders of magnitude more energy consumed for the same amount of bearing, compared to steel. Silicon carbide processing cosumes even more energy than nitride.

3alarmer 

Thus it is unlikely anyone will pay attention to him.................

+1 on the setting fire to money..........I do that all the time when I'm bored,
but don't have the time to actually work on my bike.

Burton

LOL - if you really worked in aerospace as an engineer you should know that there are important relationships that need to be maintained between the relative hardness of the bearing races and the actual bearing balls or cylinders - which are already speced to be harder than the races themselves. Problem is - when you exceed that ratio (which will happen when you replace your stock balls with ceramics) - you'll actually wear out the races FASTER.

NASA has done and is still doing extensive testing in bearing materials for their projects. Currently 60NiTi is the material of choice. Not as hard as ceramics, but far more elastic and able to produce a bearing with a much longer service life.

Long story short - sticking ceramic balls in a bearing race not specifically designed for them isn't just a waste of money - it'll actually wear out the races faster. Anything else just happens in your head.

PS: If you insist on continuing to post your aerospace experience - please at least use proper spelling, diction and sentence contruction. So far you're just making the rest of us in that field look uneducated.

Airburst

Not being funny here, but I'm 90% sure my frying pan is aluminium. Aren't most ceramics pretty good thermal insulators?

ythe1300

There are some pans that have a ceramic coating but a chef will never use one because they don't heat evenly, lose their heat quickly and they tend to flake and wear out faster than cast iron or copper / aluminum pans. But some people buy them because they are easier to clean.....

wroomwroomoops

The problem is the word "ceramic", which is too generic. But generally, the super hard "ceramics" are excellent at heat conduction.

wroomwroomoops

So THAT is your bias! I was wondering where your stubbornness is coming from. Now I know.

Ray Evans

Yes we all love riding of course I do about 40 clicks daily. Just wondering. How many times have you rode on ceramic bearings? you seem very sure they are inferior. "A true upgrade". No one in this forum has disputed that a grade 5 ball is a grade five ball regardless of what is made of. As far as i can reason the dispute is not that ceramics arent as good as steel but whether they are significantly noticeably so. And for the price.

Ray Evans

you mean they are easier to clean becuase they are slippery or a good coefficient of friction??

Ray Evans

yeh thats my bias i started using them because I commute 40klms everyday and in the winter it is a little hard in Sweden -20 degrees on a good day. I am so in love with the result that I decided to buy them bulk combine them with SKF brand lithium soap and sell them at a price everyone can afford.
You can also find some tips on carbon fiber on my site if your interested because I think that is the only way to travel also. And if i can get some quality frames from Tiawan cheap I will also pass on the savings there.
And i am experimenting on Bamboo as an ecological alternative building material.
I hope its not a crime. I do have a bias but I also have knowledge about the subject and have worked in engineering for nearly 40years.

Ray Evans

throw it away it will give you altimers hahaha