ceramic bearing upgrades

[Phill P]

Have any of you actually tried ceramic bearings to know the difference? How many mavic riders have swapped thier wheels for a set of stock campy wheels and noticed a difference (mavics aren't the smoothest out there, campies are very good though)

The performance gain is a kin to loosing weight off your bike, however with smoother bearings you get the gain everywhere not just going up hill, and we all know how cyclists love to spend thousands of $$$ of lighter "better" bikes.

Another advantage of ceramic bearings is not only do they start better, but the don't wear and slow down like steel bearings. We probably don't notice the deteriation of performace over time as its so subtle month to month.

They are smoother/faster, marginally lighter, and last longer. What was the last upgrade to your bike that really did all of that? And for ~$100 (for what I sell).

If you think the price is worth it, spend the money, if not save your $$s for a light weight saddle or seat post, or maybe some titanium bottle cage bolts, or those super bling ES wheels.........

I tihnk the best test would be to test on a velodrome with a power meter. Have the rider do the same speed for a number of laps and measure the average power, then have them do the same test with ceramics. In the track world a few kws can mean the difference between first and not making the podium. Check this out for being fussy about bearing performance!

http://www.cyclingnews.com/tech.php?id=tech/2006/features/meares_bt_stealth

 

[alienator]

Have any of you actually tried ceramic bearings to know the difference? How many mavic riders have swapped thier wheels for a set of stock campy wheels and noticed a difference (mavics aren't the smoothest out there, campies are very good though)

The performance gain is a kin to loosing weight off your bike, however with smoother bearings you get the gain everywhere not just going up hill, and we all know how cyclists love to spend thousands of $$$ of lighter "better" bikes.

Another advantage of ceramic bearings is not only do they start better, but the don't wear and slow down like steel bearings. We probably don't notice the deteriation of performace over time as its so subtle month to month.

They are smoother/faster, marginally lighter, and last longer. What was the last upgrade to your bike that really did all of that? And for ~$100 (for what I sell).

If you think the price is worth it, spend the money, if not save your $$s for a light weight saddle or seat post, or maybe some titanium bottle cage bolts, or those super bling ES wheels.........

I tihnk the best test would be to test on a velodrome with a power meter. Have the rider do the same speed for a number of laps and measure the average power, then have them do the same test with ceramics. In the track world a few kws can mean the difference between first and not making the podium. Check this out for being fussy about bearing performance!

http://www.cyclingnews.com/tech.php?id=tech/2006/features/meares_bt_stealth

No, the best test is done in the lab, where a rider can be completely removed from the equation, and where the load on the bearings--including preload--can be accurately controlledl. The lab is the only place where every thing can be held constant so that the only thing being measured is the difference in bearing drag between ceramic and non-ceramic bearings. Likewise, the lab is the best place to test bearing lifetime.

How good ceramic bearings are is not just a matter of ceramic vs. non-ceramic. It is also a question of bearing quality--and the quality of ceramic bearings varies greatly just like with non-ceramic bearings--type and quality of bearing races, type and quality of bearing lubes, and precision in bearing alignment and loading. Cees Beers(inventor of ADA wheels; designer of Mavic's newest wheels which have yet to be released; and all around knowledgeable guy) did some laboratory analysis of these differences and found that the difference in bearing performance between ceramic and metallic bearings was pretty damned small. If you search Fairwheel Bikes forums or Weight Weenies Road forum for "Cees ceramic bearings", you should find his postings on the matter.

The only thing you can be sure of is that FSA's claims (and FSA uses comparitively **** bearings) and some of the claims by certain magazines are, uhm, outlandish, at best.

 

[Phill P]

I'd like somebody to do a real decent lab test of bearing quality. All the tests and reviews I've read have been terrible and ended up being subjective. I agree all have to take as many veriables out of the equation as possible.

If bearing quality plays such a small part then why don't entry level wheels roll as nicely as top line ones? Tolerances and quality of bearings? Steel balls are accurate to 25 millionths of a mm, ceramic balls are 5 millionths of a mm (smaller is better). And they stay that way long after a steel ball has degraded from its lesser starting point.

The grade 5 ceramic bearings have to be far better controlled than the grade 25 steel balls, otherwise they wouldn't be grade 5.

 

[alienator]

If bearing quality plays such a small part then why don't entry level wheels roll as nicely as top line ones? Tolerances and quality of bearings? Steel balls are accurate to 25 millionths of a mm, ceramic balls are 5 millionths of a mm (smaller is better). And they stay that way long after a steel ball has degraded from its lesser starting point.

The grade 5 ceramic bearings have to be far better controlled than the grade 25 steel balls, otherwise they wouldn't be grade 5.

I never said bearing quality wasn't important, but bearing quality may not impact power output as much as people say or claim. Why do better bearings yield better performance? Well, for all the reasons you think. First you better include bearing races in the definition of a bearings, since races are necessary.

With greater surface errors, lower quality bearings must generate more drag in the lubricant used. Also I imagine it's possible and probable that the areas of large surface error might protrude all the way through the liquid wedge formed by the lubricant, causing metal to metal, ceramic to ceramic, metal to plastic, or ceramic to metal/plastic contact, which will in turn cause friction and generate heat, which will tend to make the lubricant break down, further increasing friction. There may be other factors, or some of the factors I mentioned may end up being small.

It is a fact that FSA's magical ceramic bearings are far from the best quality ceramic bearings. I did hear an engineer say that better or the best metal bearings are better than mediocre or bad ceramic bearings.

If a person wants the best or very good ceramic bearings and the matching races, they're going to have to pay a lot of money for 'em. A lot. And according to Cees Beers, the performance benefit of even the best ceramic bearings on a bicycle are going to be very small. Remember, that a bicycle already has a mechanical efficiency of between 96 and 98%, depending on who you listen to or who you believe. So, huge improvements are going to be hard to come by.

 

[alienator]

I'd like somebody to do a real decent lab test of bearing quality. All the tests and reviews I've read have been terrible and ended up being subjective. I agree all have to take as many veriables out of the equation as possible.

You're right about the tests written about so far being terrible. I think the problem is that the people that pay for the tests want too many different sorts of answers from their tests.....and the people doing the tests are happy to do whatever the customer asks for. I also think that magazines and some other sources of info are very guilty of reading things, in test results, that aren't actually there. If the customer paying for the tests can't ask the right question, how can you expect them to deduce the right answer from their results?

The difficulty in any good test or experiment is isolating the variables you want to isolate and holding constant the variables you want to hold constant. You can ask the cold fusion guys--Pons and Fleischman--about this: their experimental setup was poor and netted results that didn't coorelate with reality and physics, at all. Thus, no one was able to replicate their results, and they became laughing-stocks of the Physics and Chemistry worlds.

 

[ScienceIsCool]

I find the idea of ceramic bearings to be a bit silly. In a radially loaded bearing on a bicycle, the major source of friction (other than the grease, which dominates!) is the hysteresis in deformation of the bearing and race. Okay, your ceramic bearing is harder and deforms less. The bearing of a higher grade has larger contact surface area and deforms less. These combine to reduce friction by a tiny amount. And I do mean tiny. The lubricant and seals on bicycle bearings are the dominant sources of friction.

In a bicycle application the radially loaded bearings experience high loads at very low rpm (~ 50 kg at 100 rpm per wheel, sitting in a 40'C environment). Compare that to something like a jet engine where the turbine shaft can exert 1000's of kg of load at 30,000 rpm and at many hundreds of degrees.

This is why they developed ceramic bearings. In such an extreme environment, steel bearings change dimensions (i.e., thermal expansion) and start to go a bit soft. This jacks up the friction by a -huge- amount. In comparison the ceramic bearing stays dimensionally stable and nice and hard.

Ceramic bearings for bicycles is a great way to lighten your wallet and that's about it. Want to reduce friction? Spend that money on chains and replace then every week. Get really cheap bearings with no seals and remove the grease. Replace those weekly too.

John Swanson
www.bikephysics.com

 

[pistole]

I find the idea of ceramic bearings to be a bit silly

.

 

[bobbyOCR]

ceramic bearings on a Gossamer is also a bit silly.

 

[alienator]

ceramic bearings on a Gossamer is also a bit silly.

Yup. Even if it is Fabian Cancellara's. FSA's claims for performance gains as a result of ceramic bearings are laughable. Hysterical. And about as accurate as their claimed weights, which is to say not at all.

Besides a product's use on a pro bike is proof of nothing other than the team met a sponsor's desires.

 

[bobbyOCR]

Yup. Even if it is Fabian Cancellara's..

Fabian Cancellara's bike is less of an accurate representation of good products, he is a sponsored cyclist, as you mentioned.

if you want good, reliable equipment choice, find you local successful masters category racers and have a look at their bikes. Rolls saddles are great.